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class="h pbm"> <h1 class="ph"> 寻找生命的源头 </h1> <p class="xg2"> <span class="xg1">已有 2789 次阅读</span> <span class="xg1">2023-12-9 22:17</span> <span class="pipe">|</span><span class="xg1">系统分类:<a href="https://blog.sciencenet.cn/home.php?mod=space&do=blog&view=all&uid=3469996&catid=10">人文社科</a></span> </p> </div> <div id="blog_article" class="d cl" ><h1 class="ph" style="overflow-wrap: break-word; margin: 0px; padding: 15px 0px 10px; font-size: 20px; font-family: "Microsoft YaHei", "Hiragino Sans GB", STHeiti, Tahoma, SimHei, sans-serif; font-weight: 100; color: rgb(47, 73, 111);">生物的故事丨寻找生命的源头</h1><p class="xg2" style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; color: rgb(102, 102, 102);"><span class="xg1" style="overflow-wrap: break-word; color: #999999 !important;">已有 8814 次阅读</span> <span class="xg1" style="overflow-wrap: break-word; color: #999999 !important;">2018-4-23 16:16</span> <span class="pipe" style="overflow-wrap: break-word; margin: 0px 5px; color: #CCCCCC;">|</span><span class="xg1" style="overflow-wrap: break-word; color: #999999 !important;">个人分类:<a href="https://blog.sciencenet.cn/home.php?mod=space&uid=528739&do=blog&classid=163255&view=me" style="overflow-wrap: break-word; color: rgb(47, 73, 111); text-decoration-line: none;" target="_blank">科学书摘</a></span><span class="pipe" style="overflow-wrap: break-word; margin: 0px 5px; color: #CCCCCC;">|</span><span class="xg1" style="overflow-wrap: break-word; color: #999999 !important;">系统分类:<a href="https://blog.sciencenet.cn/home.php?mod=space&do=blog&view=all&uid=528739&catid=7" style="overflow-wrap: break-word; color: rgb(47, 73, 111); text-decoration-line: none;" target="_blank">科普集锦</a></span><span class="pipe" style="overflow-wrap: break-word; margin: 0px 5px; color: #CCCCCC;">|</span> <span class="ptg xg1" style="overflow-wrap: break-word; padding-left: 20px; background-image: url("http://blog.sciencenet.cn/static/image/common/tag.gif"); background-position: 0px 2px; background-size: initial; background-repeat: no-repeat; background-attachment: initial; background-origin: initial; background-clip: initial; color: #999999 !important;">生物的故事, 杨天林, 科学出版社, 生命, 源头</span></p><blockquote style="overflow-wrap: break-word; font-family: Tahoma, Helvetica, SimSun, sans-serif, Hei; text-wrap: wrap; background-color: rgb(255, 255, 255);"><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; text-indent: 2em;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;">地球的历史至少有46 亿年，人类的历史有300 万年左右。放在地球演化的大背景下，人类的生命史只不过是地质历史长河中短暂的一瞬间，个体生命更加渺不可及。</span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; text-indent: 2em;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;"><br/></span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; text-indent: 2em;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;">对几十亿年前发生的事情，我们几乎无能为力，因为我们不能亲身经历，也无法直接观测。幸好有化石存在，我们可以借此了解过去，甚至还能基于某种数学模型进行计算和模拟。</span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; text-indent: 2em;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;"><br/></span></p></blockquote><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; font-family: Tahoma, Helvetica, SimSun, sans-serif, Hei; text-wrap: wrap; background-color: rgb(255, 255, 255); text-align: center;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;"><img src="http://image.sciencenet.cn/home/201804/23/160227nazcqjzo3r65ctd0.jpg" title="" alt="timg.jpg" style="overflow-wrap: break-word; max-width: 620px;"/></span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; font-family: Tahoma, Helvetica, SimSun, sans-serif, Hei; text-wrap: wrap; background-color: rgb(255, 255, 255);"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;"><br/></span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; font-family: Tahoma, Helvetica, SimSun, sans-serif, Hei; text-wrap: wrap; background-color: rgb(255, 255, 255); text-align: center;"><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">细胞：生命进化的重要阶梯</span></strong></span><span style="overflow-wrap: break-word; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: 15px; text-align: justify;"><br/></span></p><p style="overflow-wrap: break-word; margin-top: 1.12em; margin-bottom: 1.12em; padding: 0px; font-family: Tahoma, Helvetica, SimSun, sans-serif, Hei; text-wrap: wrap; background-color: rgb(255, 255, 255);"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">从生物大分子物质进化到多分子体系是早期生命演化的第三阶段。生命体内的多分子体系实质上是某种具有一定生命周期的团聚体。苏联生物化学家亚历山大·伊万诺维奇·奥巴林（Oparin Alexander Ivanovich，1894—1980）最早提出了团聚体假说。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">奥巴林认为，团聚体能够表现出合成、分解、生长、生殖等生命现象。团聚体具有类似于膜的边界，膜两边的溶液环境和化学特征有很大区别。比如，团聚体能从外部溶液中吸入某些分子作为反应物，还能在酶的催化作用下发生特定的生化反应，反应的产物也能从团聚体中释放出去。当然也有其他一些假说，如微球体假说和脂球体假说，这些假说都是为了解释有机高分子物质形成多分子体系的过程。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">团聚体假说并非空穴来风。奥巴林做了一系列实验，实验表明，将蛋白质、多肽、核酸和多糖等物质放在合适的溶液中，它们能自动地浓缩聚集为分散的球状小滴，这些小滴就是团聚体。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">生命演化的第四阶段，就是有机多分子体系演变为原始生命。这一阶段是生命起源过程中最复杂、最有决定意义的阶段。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">截至目前，人们还不能在实验室里验证这一过程。但我们坚信，在对化石和现存生命现象的研究中，生命是从最原始的无细胞原核生物进化为单细胞真核生物。然后，又按照不同的方向发展和演化，并向着真菌界、植物界和动物界方向发展。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">由于自然选择机制的作用，生命生发系统可能是一些分散、半自主和可以自我复制的单位，这些单位就是原细胞。每一个单位都有自己的独立基因组。基因的变异仅对其所负载的原细胞起作用，结果就使这个原细胞带着进化了的基因组以更快的速度繁衍，以与其他原细胞争夺生存空间。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">在冥古宙早期，一些不完全有生命性质的物质含有DNA，可以自我复制，但不能有效地贮存能量；另一些物质能够很有效地保持能量平衡，但自我复制的功能却弱得多。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">后来，经过漫长时间，它们在共同存在的过程中能够进行某种组合，互相补偿对方的缺陷，形成了生命世界的第一个细胞。这种空间上和能量上的互补和协同作用赋予它们更高的效率。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">最早的细胞具有一个富含DNA 却不能利用氧的细胞核，以及大量的能够高效率地利用氧但在没有细胞核的情况下就不能自我复制的线粒体。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">细胞是生命的基本单元。单个细胞具有生命的所有属性，包括复制；生物体的所有复杂器官，无论它们的功能是什么，都是由细胞构成的。一个动物的受精卵，或者一个植物的种子，都包含众多能够分裂并成长为成年生物的单细胞。细胞的重要特点是分裂与倍增，而且数量惊人。人体中有大约100 万亿个细胞，细胞总数大致为整个银河系中明亮的恒星总数的1000 倍。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">每个细胞都被一层膜包裹着，这层膜里面装的是浆状物质（细胞溶质或胞液），在植物细胞中，包含叶绿素并参加光合作用的叶绿体根据DNA 中的编码指令，将水和二氧化碳等简单成分合成为生命所需的有机分子。在细胞的“心脏”部分，包裹在另一层膜中的是细胞核。细胞核外面的所有物质叫作细胞质，细胞的工作就在这里进行。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">我们暂且不去关心这些，而是将精力集中在DNA 本身，它在细胞核内部储存的结构单元称为染色体。生物体的生长就是生物体的细胞不断通过分化、增殖增加品种和数量的过程。在分裂增殖的过程中，细胞核中的所有染色体都进行了复制。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">在生命起源的所有过程中，细胞都扮演了非常重要的角色。它们参与了生命早期的顶层设计，甚至还在前生命时代的“原始汤”时期，一群一群的细胞已经开始施展拳脚了。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">原核和真核世界中的大多数细胞皆由细胞膜外部的结构包围，从柔软的绒毛到坚硬的细胞壁都属于这些外部结构。它们用来支持和保护细胞，充当分子过滤器的作用，同时也使细胞与外界隔开一定空间。包括蛋白质、脂类、复杂糖类等在内的多种物质都参与构建了这些胞外结构。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">染色体是DNA 与蛋白质的混合物。每条染色体都携带着大量的DNA。细胞在有丝分裂过程中展开这些染色体并对其复制，其顺利程度令人惊讶。那些有性繁殖的物种都有两套染色体，分别从两个亲本那里继承而来，这使得复制的数量增加了1 倍。例如在人体内有23 对染色体，它们携带了有关如何建造和管理人体的全部信息，这些信息被编码在许多更短的一小段DNA 里，称为基因。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">它们都属于生命源头的物质，具有生物活性。活性分子是创造生命世界的原始祖先。在我们的感觉中，虽然那些形形色色的生命有着巨大差别，但有一点是非常类同的，那就是它们的细胞都以非常相近的方式进行着代谢过程。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">细菌：最古老的生命形式</span></strong></span><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">经过长期的研究和探讨，我们能够对生命物质所具有的基本特征进行一般的概括，这就是，通过一系列的过程和变化，能够把外界物质中的养料转换成建造自身的物质基础，并将能量储存起来，这是新陈代谢的基础；能够繁殖后代，并使后代按照遗传的特征生长、发育和运动，这是一个自然的过程；在环境变化的时候，能够对外部环境产生一定的适应能力，这是一个适应环境并在适应中改变和调整自己属性的过程。为了便于记忆，我们可以把这几个特征总结为新陈代谢、发育繁殖、适应环境。这几句话虽然简单，但要真正理解生命的特征和本质，却不是一件简单的事情。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">科学家发现的最早的古生物化石是32 亿年前的细菌化石。原始细菌是最早的原核细胞生物，实际上，它们在地层中留下了许多活动痕迹。在非洲、澳大利亚和加拿大等地都发现了一些叫作叠层石的岩石层，其中记录了远古时代的原核细胞生物活动的痕迹。据地质学家和古生物学家推算，这些岩层的地质年龄约有35 亿年，这意味着，最早的原核细胞生物在35 亿年前就已经出现。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">分子进化研究表明，原始细菌中核糖体RNA（rRNA）的分子序列与一般细菌的rRNA 分子序列十分不同，其相差程度比一般细菌rRNA分子序列与真核生物（细胞中含有细胞核的生物）rRNA 分子序列的差异还要大。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">科学家认为，这些非同寻常的细菌应该代表一个既不同于一般细菌也不同于真核生物的生物类群，因此把它们称为古细菌（或古核生物），而把一般细菌称为真细菌（或原核生物）。因此，地球上最初的原核细胞生物是古核生物而不是原核生物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真细菌在很多分子生物学和细胞生物学性状上与古细菌相差甚远，它们拥有不少进化的或特化的性状。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">在现代生物学中，把细菌类都归结为最简单的无核单细胞生物，它们都是简单、低级和原始的生物，已经进化了至少30 亿年时间，从这个角度看，它们也是现代生物的一种。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">古细菌的后裔至今犹存。从现代细菌中几种特殊的细菌那里就能隐约看到古细菌的影子，包括能够利用二氧化碳和氢气产生甲烷的厌氧细菌、能够生长在极浓盐水里的盐细菌、能够在自然的煤堆里生长的嗜热细菌，及能够在硫黄温泉或海底火山区生长的嗜硫细菌，类似的例子还有很多。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 15px; background-color: #F2F2F2;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 16px;">藻类：没有种子，也不会开花结果</span></strong></strong></span></strong><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 16px;"></span></strong></strong></span></strong><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"></strong></strong></span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">藻类是微小的植物，看上去很不起眼，数量却非常多。只要有阳光和水，藻类就能够生存。大部分藻类都存在于陆地水系中，它们比真正的植物简单，但生存方式与植物相同，光合作用是它们得以生存的基础。对水生生态系统而言，藻类的存在至关重要，它们处在食物链的上端，时刻为下端的生命提供源源不断的能量需求。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">当藻类广泛占据河流、湖泊和海洋的时候，陆地上还是一片荒芜。我们常常对藻类习以为常，其实藻类在形态上是一类非常奇特的生命，它们的生命历史即使不是最悠久，也是其中之一。直到今天，藻类依然繁盛，在随便一处池塘或沟渠里，都能看到它们的身影，它们随着水的漂移而前进。甚至在盛有水的瓶子里，都能感受到藻类顽强的生命力。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">藻类属于原生生物，一些种类只有一个细胞，属于单细胞植物。与一般原生生物不同的是，藻类细胞常常集结在一起，组成一个叫作群的部落，每一个个体在那个群里繁衍生息。当条件理想时，它们的繁殖速度特别快，用不了多久，就会将一池水变得色彩斑斓。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">藻类没有种子，也不会开花结果，它们通过不断分裂而达到繁殖的目的，这种繁殖方式既简单又特别，还非常高效和快捷。藻类能够感受到阳光的明媚和春天的温暖，那一段时间是藻类分裂繁殖的最佳季节。其结果就是在不长的时间内，藻类迅速生长。有了藻类的充分供给，位于食物链下方的浮游生物、鱼类和其他动物也就衣食无忧了。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">随着体形增大，藻类身体中包含的细胞开始增多，这对它们的繁殖非常不利。为了解决这个问题，体形较大的藻类就会通过孢子繁殖。孢子有点儿像种子，但个头要小得多，一阵风就可以把它们带到遥远的地方，或随着水流到远方建立新的家园。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">一些藻类还会游泳，它们游泳的方式是滑动纤毛，缓慢推进，直到找到充足的阳光和适宜的环境。对它们来说，阳光就意味着能量，能量就是它们繁衍生息的力量。有些海藻只有几厘米长，最大的海藻则长达几米。在北美洲西海岸生活着一种巨藻，它们的生长速度非常快，是世界上著名的天然速生生物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">尽管藻类的种类很多，但它们不是一个独立的自然类群，而是一个非常庞大的集群。我们习惯把这个集群叫作藻类，属于最低等的植物之一。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">真菌：游离在植物与动物之间</span></strong></span><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真菌和一般植物有很多相似之处，它们大多从地上或枯木上开始萌发，然后通过孢子传播后代。然而这仅仅是一种表面现象。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">在本质上，真菌和植物是两种完全不同的生物，真菌通过分解它们周围的物质来获取生存所需要的养分，植物则通过它们的叶子吸收阳光来获取能量，说植物不需要食物也不太正确，但它们的食物是如此的简单和不可思议——水和二氧化碳触手可及，至少在地球上是这样。目前已经发现的真菌约有10 万种，植物则是真菌的4 倍还多。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真菌是地球上常见的生物，我们最熟悉的可能就是各种各样的蘑菇，但蘑菇只不过是真菌中极小的一部分。大多数真菌体形都很小，也有体形巨大的种类。在森林、海底和人的皮肤上，甚至在沙漠深处，都能找到真菌活动的踪迹。大多数死去生物的残骸就是真菌的最爱，还有一些真菌喜欢生活在活的机体中，只是人们平时很少注意到。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">很多年前，人们认为真菌是植物，不过这种想法后来得到修正，和植物相比，真菌与动物的关系更亲近。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真菌的形状和大小不一。它们并不像动物那样直接吞咽食物，而是会吸收和消化那些所谓的食物释放出来的营养。执行这一任务的就是菌丝，菌丝是一种极细极长的组织。有些菌丝长得惊人，会从地面一直延伸到树顶，并在土壤中形成细密的菌丝网络，有些食木菌甚至可以沿着一条街道挨家挨户地传播。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真菌是一种陆生真核生物，是具有真核和细胞壁的异养生物。真菌通常属于多细胞生物。大多数真菌能分解动植物的残骸，使许多重要化学元素进入再循环，直接或间接地影响着地球生物圈的物质循环和能量转换。大部分真菌是腐生生物，以死亡的或正在分解的有机体为食。像念珠菌这样的真菌以活的有机体为食，这样的情况并不是太多。像地衣这样的真菌则与其他生物共存共荣。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">真菌的繁殖包括无性繁殖和有性生殖。无性繁殖是指营养体不经过核配和减数分裂产生后代个体的繁殖；有性生殖是指真菌生长发育到一定时期，经过两个性细胞结合后细胞核产生减数分裂，从而产生孢子的繁殖方式。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">大部分真菌的营养体是由纤细管状菌丝构成的菌丝体。在真菌的细胞壁中，多数含有甲壳质，其次是纤维素。常见的真菌细胞器有细胞核、线粒体、微体、核糖体、液泡、溶酶体、泡囊、内质网、微管和鞭毛等。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">常见真菌包括酵母菌、霉菌和蕈菌（大型真菌）。大型真菌是指能形成肉质或胶质的子实体或菌核，其代表物比较常见的有香菇、草菇、金针菇、双孢蘑菇、平菇、木耳、银耳、竹荪、羊肚菌等，很多都是人类餐桌上的食品。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">一些真菌味道鲜美，比如某些可以食用的蘑菇；也有许多真菌中可能含有致命的毒素。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">毒蕈是分布于北半球林地中的毒蘑菇，其外形类似于食用蘑菇，但其毒性非常大，误食一株就可能致命，毒性常常会在食用之后的12小时发作，所以，当误食毒蕈的人感到不舒服的时候已经来不及了。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">1928 年，苏格兰生物学家亚历山大·弗莱明（Alexander Fleming，1881—1955）在实验室中发现一个培养皿中的霉菌有些异常，这个培养皿通常用于培养细菌，但是霉菌导致周围的细菌全部死去，这是一种神奇的现象。后来，人们从这种霉菌中成功分离出了一种化学物质，这种化学物质可以杀死细菌，这就是我们最熟悉的青霉素（Penicillin），它是最重要的抗生素，也是目前世界上最重要的药物之一。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">对有些动物来说，真菌的存在至关重要，比如蘑菇是鼻涕虫和某些昆虫幼虫的食物来源，鼻涕虫是一种小型动物，它们利用齿舌吞噬真菌——齿舌是一种包含数百颗微型牙齿的口器。有些真菌会无声无息地侵入动物体内，动物往往在不知不觉中就会毙命。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">许多昆虫在树木中产卵，幼虫出生后就以栖居的家园为食，它们通常在针叶树中钻洞。蛀空的树木又成为真菌的居所，不断增多的真菌和树木一起成为幼虫的大餐。幼虫活动的地方布满了真菌形成的“皮毛”，幼虫就以它们为食。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">足癣是一种由以人类表皮为食的真菌引起的皮肤病，在温暖潮湿的环境下，这种真菌会大量滋生，很多人都遭受到它的侵袭。患足癣以后虽然很麻烦，但不必恐慌，积极治疗，注意卫生，防止自身传染及继发感染。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><img src="http://image.sciencenet.cn/home/201804/23/160715lw5jip26jf52vdph.bmp" title="" alt="" style="overflow-wrap: break-word; max-width: 620px; display: inline;"/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px;">蘑菇也属于真菌类</span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px;"><br/></span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 16px;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: medium;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 16px;">微生物：不仅仅是微小的生物</span></strong></span></strong></span></strong></strong></span></strong><br/></span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">微生物其实是个广义名称，说它们是微小的生物好像也没错。仅从体积方面来看，微生物确实有些微不足道。很多微生物只有粉尘般大小，还有一些微生物需要放大几千倍才能被看见，可见其之微小。病毒是其中个体最小而数量最多的群体，次之便是体形较大、单细胞的原生生物。微生物还包括微小的真菌及一些特别微小的动植物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">体形微小是一种天然优势，这意味着它们的栖息地无处不在。大多数微生物生活在水中或潮湿的地方，泥土特别是含有大量动植物尸体的泥土是它们最爱居住的地方。动物的皮肤、口腔、牙齿及身体内部的许多地方同样是它们生活的天堂。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">微生物是地球上最基础的生物。在自然界中，微生物是不可缺少的一环，也是食物链的重要组成部分，它们和其他生命群体一起，完善着进化的过程。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">一些微生物对动植物有害，它们侵入动植物体内，以栖居之所为食，它们就是我们常说的病原体，一些疾病的发生就与它们有关。不过动植物在漫长的进化过程中也具有了抵抗那些微小侵略者的能力，使自己受到特殊防护，才不至于在这些微生物的侵略面前全线溃败。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">但更多的微生物是无害的，有些甚至还是有益的。当动物处于良好的健康状况时，居住在其体内的细菌就与周围的环境和谐共存，齐心协力地维护着它们共同的家园。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">我们很难对微生物所在的世界做出感性判断。人常常能感受到重力对自己身体的影响，但微生物完全不一样，重力对它们几乎没有什么影响，因为它们的体重如此之小，以至于基本上不受地球引力的影响。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">微生物居无定所，没有什么可以将它们与外部世界隔开。一阵风，甚至是轻微的气流就可以使它们背井离乡，并且很难再回到它们曾经生活过的地方。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">为了生存下去，很多微生物都会采取一套独特而有效的措施。比如，它们常常通过自我“关闭”来度过艰难困苦的时期，有时候，“关闭期”可以长达几个月，有些微生物甚至可以保持睡眠状态达10 年以上。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">尽管没有一种高等动物能够消化纤维素，但有些微生物却能做到这一点，例如寄居在反刍动物和白蚁肠道中的微生物就能够以纤维素为食。这类微生物能够把大量的纤维素转化成葡萄糖，消耗掉自己所需要的一部分葡萄糖后，把更多剩余的葡萄糖供给寄主。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">在这个例子中，微生物供应加工过的食物，寄主提供原料和住所，两种生物相互依存，相得益彰，在各自的生态位上尽职尽责。它们之间这种互惠的合作方式就是我们常说的“共生现象”。多亏了这些默默无闻的微生物的帮助，牛才能靠吃草而生存，白蚁才能靠吃木头而活命。它们固守着属于自己的生态位，共同维护着生命的平衡关系。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">病毒：在流浪中寻找衣食父母</span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><br/></span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><span style="overflow-wrap: break-word; color: #FFC000;"></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">病毒比细菌更小、更简单，也表现出生命的特性，它们只能依靠其他生物存活，具体来说，它们通过攻击活细胞而维持生命。与其他微生物不同的是，除非进入适宜的宿主细胞中，病毒自身不能生长，也不能繁殖。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">病毒的传播能力极强，很难被控制。绝大多数病毒的体形远远小于细菌。与其说它们是生物，不如说它们是一种有机机器。病毒的化学组成相当精密，在形成病毒时，一定是进行了考究的分子自组装。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">病毒并不需要进食，它们犹如一个劫匪，通过“劫持”活细胞而强迫细胞复制病毒，病毒攻击的宿主包括细菌、植物和动物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">大部分生物每天都会受到病毒的攻击，不过，大多数病毒只会造成很小的危害，尽管如此，对少数病毒对生命造成的伤害仍然不可以掉以轻心。人类免疫缺陷病毒（Human Immunodeficiency Virus，HIV）病毒会导致艾滋病的发生，这种疾病对人类造成的危害已经到了触目惊心的程度。截至目前，人类还不知道病毒到底来自何方，一种理论认为，病毒是从活体生物中逃脱出来的“背叛”基因。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">病毒只能在活细胞化学体系的帮助下完成复制。脊髓灰质炎、狂犬病、天花和麻疹等，都是从动物或人的细胞中复制出来的病毒引起的疾病。还存在着可以感染植物细胞、原生生物或细菌的病毒。所有病毒都有携带遗传模板的基因组，而且都可以将它们导入细胞复制增殖。有些病毒具有DNA 型基因组，有些病毒则具有RNA 型基因组。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">病毒常常从一个细胞流浪到另一个细胞，走到哪里吃到哪里，没有可吃的东西时也能忍饥挨饿很多天，甚至几个月。在生命发展的早期阶段，有些病毒可能就习惯了流浪生活，特别是RNA 病毒，它的产生可以追溯到原细胞清除RNA 复制酶和反转录酶的那个时期。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><span style="overflow-wrap: break-word; color: #FFC000;"></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><span style="overflow-wrap: break-word;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">原生生物：寄生生活也丰富多彩</span></strong></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><span style="overflow-wrap: break-word;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><br/></span></strong></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><span style="overflow-wrap: break-word;"></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">大多数原生生物只有一个细胞，但其构造相对复杂一些，不同的构造对应着不同的功能。原生生物通常生活在水中，有些种类的举止类似于微型动物，有些则类似于微型植物。放射虫是一种生活在海洋中的原生生物，它们使用黏性丝线来捕捉比自己体形更小的猎物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">一些原生动物寄生在其他生物体内，不过只有少数会致病。更多的原生动物生活在水中。原生动物体形很小，在显微镜下，看起来好像是处于高速运行中，它们会绕开障碍物，然后迅速集合在食物周围。原生动物其实并不是动物，它们没有眼睛和嘴巴，甚至没有大脑，充其量只能算是一个细胞，是一种真核单细胞微生物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">与藻类不同，原生动物需要进食，而且进食的方式各种各样。许多原生动物都是积极的掠食者，另外一些则静止不动，依靠漂流到附近的任何可食物质为生。放射虫是一种生活在海洋中的原生动物，其骨骼多刺，活的放射虫会从骨骼中伸出胶冻状的细丝，捕捉附近的漂流微生物。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">原生动物体形微小，没有四肢，但它们擅长四处活动。阿米巴虫通过变化体形移动，这种能力对于通过狭窄的缝隙尤其有用。当阿米巴虫追踪猎物时，会将其包围，然后吞噬，整个过程就像猎物被一个有生命力的果冻给吞噬掉了。即便阿米巴虫用尽全力，其时速也不会超过2 厘米，真是慢得不能再慢了。可是池塘里或湖泊中的有些原生动物的移动速度却要快得多，会达到阿米巴虫的几十倍，像草履虫的移动速度就很快。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">原生动物是极其重要的浮游生物，也是食物链中的重要一环。一些原生动物的居住环境比较特殊——在植食性动物的肠和胃里，它们帮助主人分解食物。一头成年大象的肠道里就生活着几十亿个原生动物，由于数量极其庞大，因而总能圆满地完成工作。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">生活在生物体内真是一件幸福的事情，可以说是居有定所，衣食无忧，拥有丰富多样且源源不断的食物供应，还有一个温暖舒适的居住环境。怪不得它们那么乐不思蜀呢！不过，这样的好日子可能不会长久，有时候，动物肠道的不断蠕动就会将许多原生动物冲到下游，并最终冲出体外。它们随时都面临着失去“家园”、背井离乡的危险。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">寄生类原生动物经常游到一些水源地，或者通过昆虫叮咬而传播到动物体内。几乎所有的野生动物都受到原生动物寄生虫的影响，只不过危害不大。也有十分危险的原生动物，引起疟疾的原生动物——疟原虫不仅能影响人类和其他哺乳动物，还会危及爬行动物和鸟类。疟疾是一种很危险的疾病，在医疗水平很低时甚至会致死。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000; background-color: #F2F2F2;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;">源头在哪里？</span></strong></span><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000; background-color: #F2F2F2;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px; color: rgb(255, 255, 255); font-size: medium; text-align: justify;"><span style="overflow-wrap: break-word; color: #FFC000; margin: 0px; padding: 0px; font-size: 16px;"><br/></span></strong></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><span style="overflow-wrap: break-word;"></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">地球上生命存在的最早证据来自年龄约达30 亿年的岩石。从那时起，在以后近20 亿年的漫长时间里，原核生物大概是其中唯一的种属。零散的化石记录模模糊糊地证明了这一点。然而，关于真核生物还没有准确的化石记录。蓝绿藻肯定是那个时候地球上最复杂的生命形式。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">今天，古生物学研究已经证实：大约30 亿年前，地球上就存在着细菌和蓝绿藻两类生命系统。那些被埋在深山老沟里古老岩层下的细小化石默默印证着20 亿—30 亿年前生命的繁荣景象，让人们认识到了时间的深刻穿透力，并会产生一种物是人非的慨叹。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">说实话，我们对20 亿—30 亿年前地球景观和生命形态的认识是模糊的，肯定也是肤浅的，甚至还可能是错误的。时间不会倒流，消逝的东西不会给我们留下多少记忆，一切曾经辉煌过、繁荣过的生命早已变成了岩石和泥土的一部分。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"> </span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">婴儿时期的地球岩石不会给我们留下多少记录，我们对那些原始生命的一般特征和形态缺乏最起码的了解，即使是后来具有柔软身体和躯干的生命也会灰飞烟灭。只有那些具有骨骸或其他坚硬部分的生物，以及那些本身就身披甲壳或身体重到能够在泥地上留下脚印或痕迹的生物才有可能在岩石上留下记录，否则就不会留下任何记录来表明它们曾经在这个地球上存在过。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><span style="overflow-wrap: break-word;"></span></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px; color: #FFC000;"><img src="http://image.sciencenet.cn/album/201706/20/090850xh55lf533hw0ly25.jpg" style="overflow-wrap: break-word; max-width: 620px; color: rgb(51, 51, 51); font-size: 14px; font-family: tahoma, helvetica, simsun, sans-serif, hei; text-indent: 28px; letter-spacing: 2px; line-height: 25.2px; margin: 0px; padding: 0px; display: inline;"/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em;"><span style="overflow-wrap: break-word; color: #FFC000; font-size: 15px;"></span><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-indent: 2em;"><span style="overflow-wrap: break-word; font-size: 15px; text-align: justify;">本文摘编自杨天林教授著“科学的故事丛书”之《生物的故事》（杨天林著，崔衢审订）第二章，内容有删减。</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-indent: 2em;"><span style="overflow-wrap: break-word; font-size: 15px; text-align: justify;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-indent: 2em; text-align: center;"><span style="overflow-wrap: break-word; font-size: 15px; text-align: justify;"><a href="https://item.jd.com/12337936.html" target="_blank" style="overflow-wrap: break-word; color: rgb(47, 73, 111); text-decoration-line: none;" target="_blank"><img src="http://image.sciencenet.cn/home/201804/23/161401o7dgh8uud778ggbd.jpg" title="" alt="" style="overflow-wrap: break-word; border: none; max-width: 620px; display: inline;"/></a><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-indent: 2em;"><span style="overflow-wrap: break-word; font-size: 15px; text-align: justify;"><br/></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-indent: 2em;"><span style="overflow-wrap: break-word; font-size: 15px; text-align: justify;"></span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><a href="https://item.jd.com/12337936.html" target="_blank" style="overflow-wrap: break-word; color: rgb(47, 73, 111); text-decoration-line: none;" target="_blank"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">《生物的故事》</span></strong></a></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">作者：<a href="https://item.jd.com/12337936.html" target="_blank" style="overflow-wrap: break-word; color: rgb(47, 73, 111); text-decoration-line: none;" target="_blank">杨天林</a>　</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">审订：崔衢</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">责任编辑：张莉</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">北京：科学出版社，2018.4</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 14px; color: #888888;">ISBN：978-7-03-053746-1</span></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; text-align: center;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">生物学关注的不仅仅是生命现象，还有与生命现象有关的丰富知识。从最早的定性描述，到当前的分子生物学和基因表达，可佐证生物学的博大精深。</span></p><p style="overflow-wrap: break-word; margin-top: 0px; margin-bottom: 0px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium;"><br/></p><p style="overflow-wrap: break-word; margin: 0px 16px; padding: 0px; text-wrap: wrap; background-color: rgb(255, 255, 255); clear: both; font-family: "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif; font-size: medium; line-height: 1.75em; text-align: justify; text-indent: 2em;"><strong style="overflow-wrap: break-word; margin: 0px; padding: 0px;"><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">《生物的故事》</span></strong><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;">生动讲述了化石的形成、动植物概况、近代生命科学的兴起、生物进化、19世纪生物学的新突破、DNA的结构和功能的发现及基因工程等生物学发展的基本历程，从中可以发现生命源头的重要力量，了解植物和动物的边界，明白鸟类是如何起源和演化的，感受生物学家和他们的科学人生。全书力求通过一系列故事让那些科学巨人走进读者心中，希望通过他们的成长经历、探究过程给读者以启迪，在通识教育和素质教育方面做了一个很好的尝试，有助于读者理清生物科学的发展脉络。</span></p><p><span style="overflow-wrap: break-word; margin: 0px; padding: 0px; font-size: 15px;"><br/></span></p><p><br/></p> <br /><br /> <label style="font-size:13px; color:#850f0f">转载本文请联系原作者获取授权，同时请注明本文来自杨天林科学网博客。<br />链接地址：</label><a href="https://blog.sciencenet.cn/blog-3469996-1413159.html" target="_blank" style="font-size:13px; color:#850f0f">https://blog.sciencenet.cn/blog-3469996-1413159.html </a> <br /><br />上一篇：<a href='blog-3469996-1405381.html' target='_black'>宇宙微波背景辐射发现始末</a><br />下一篇：<a href='blog-3469996-1446990.html' target='_black'>我从天涯海角来</a>  </div> <div id="click_div"><table cellpadding="0" cellspacing="0" class="atd"> <tr></tr> </table> <script type="text/javascript"> function errorhandle_clickhandle(message, values) { if(values['id']) { 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