章节大纲

  • 常规

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  • 生命的特征和起源

    Erupting geyser under a cloudy sky, creating a misty landscape with distant trees.
     

    What is   life ?
    ::什么是生命?

    How can you tell a blob of  organic  material from a living creature? What characteristics does something need to be considered alive? Does this photo resemble early Earth? Erupting  geysers ? Mats of bacteria? Maybe so! Of course, you have to ignore the trees in the distance.
    ::你如何从活生物体中分辨出有机材料的浮肿? 需要将什么特征视为活体? 这张照片像地球早期吗? 喷发喷泉? 细菌的外壳? 也许如此! 当然,你必须忽略远处的树木。

    The Origin Of Life
    ::生命起源

    No one knows how or when life first began on the turbulent early Earth. The oldest known fossilized cells are about 3.5 billion years old.  However, it is possible that life originated shortly after the Earth’s oceans were formed, as early as 4.4 billion years ago.
    ::没有人知道生命是如何或何时开始于动荡的早期地球。 最古老的已知化石化化细胞有35亿年的历史。 然而,地球海洋形成后不久,早在44亿年前,生命就有可能起源于地球海洋。

    This issue of what's living and what's not is important. It helps us to think about the origin of life. When does a blob of organic material become life? As you can see, we need to have a definition of life.
    ::生命和生命无关紧要的问题。 它帮助我们思考生命的起源。 当有机材料的浮肿成为生命的时候? 正如你可以看到的, 我们需要对生命有一个定义。

    Characteristics of Life
    ::生命的特征

    To be considered alive, an organism must:
    ::要被视为活体,生物体必须:

    • be made from organic molecules (amino acids).
      ::由有机分子(氨基酸)制成。
    • have a  metabolism .
      ::具有新陈代谢。
    • be able to reproduce.
      ::能够繁殖。

    Amino acids  are molecules of carbon, hydrogen, oxygen and nitrogen. These molecules are called the building blocks of life because they create  proteins .  Proteins  are complex organic molecules that make up cells. They are the most abundant class of biological molecules.
    ::氨酸是碳、氢、氧和氮的分子。这些分子被称为生命的构件,因为它们创造蛋白质。蛋白质是组成细胞的复杂的有机分子。它们是最丰富的生物分子。

    Learning About the Origin of Life
    ::关于生命起源的学习

    To look for information regarding the origin of life, scientists:
    ::为了寻找关于生命起源的信息,科学家们:

    • perform  experiments  to recreate the environmental conditions found at that time.
      ::进行实验以重新创造当时发现的环境条件。
    • study the living creatures that make their homes in extreme environments. These environments are most like Earth’s early days.
      ::研究在极端环境中建造家园的生物。 这些环境最像地球早期。
    • seek traces of life left by ancient microorganisms, also called  microbes  ( Figure   ). These include microscopic features or chemistry left by life. It is very difficult to distinguish these from non-biological features.
      ::寻找古代微生物(又称微生物(图))留下的生命痕迹,其中包括生命留下的微小特征或化学特征,很难将这些特征与非生物特征区分开来。
    Microscopic view of microorganisms, illustrating traces of ancient life forms.
     
    How can we tell where these microbes have been?

     

    Summary
    ::摘要

    • For something to be alive it must be organic, have a metabolism, and be capable of replication.
      ::活下来的东西 必须是有机的 具有新陈代谢 并且能够复制
    • Amino acids create proteins. They are the building blocks of life.
      ::氨酸产生蛋白质,它们是生命的构件
    • To learn about the origins of life, scientists perform experiments. They study creatures that live in extreme environments. They look for traces of life that were left by ancient microbes.
      ::为了了解生命的起源,科学家们进行实验。他们研究生活在极端环境中的生物。他们寻找古代微生物留下的生命痕迹。

    Review
    ::回顾

    1. What are the characteristics of life?
      ::生命的特征是什么?
    1. What are amino acids? Why are they important?
      ::什么是氨基酸 为什么重要
    1. What are proteins? If something doesn't have proteins can it be alive?
      ::蛋白质是什么?
    1. How do scientists learn about the origins of life?
      ::科学家如何了解生命的起源?