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  • 分子证据

    Close-up of a chimpanzee's face, highlighting its expressive eyes and facial features.

    How similar are you to a chimpanzee?
    ::你和黑猩猩有多像?

    Chimpanzees and humans turn out to be very similar—if you look at their . When scientists determined the entire of both humans and chimpanzees, they found that we have over 98% identical DNA. 
    ::黑猩猩和人类看起来非常相似,如果你看看它们。当科学家确定整个人类和黑猩猩时,他们发现我们拥有98%以上的相同DNA。

    Molecular Evidence
    ::分子证据

    Arguably, some of the best evidence of evolution comes from examining the molecules and DNA found in all living things.
    ::可以说,一些进化的最佳证据 来自于对所有生物中发现的分子 和DNA的检查。

    Beginning in the 1940s, scientists studying molecules and DNA have confirmed conclusions about evolution drawn from other forms of evidence. are used to determine how closely two are related by calculating the number of differences between the species' DNA sequences or amino acid sequences. These clocks are sometimes called gene clocks or evolutionary clocks. The fewer the differences, the less time since the species split from each other and began to evolve into different species ( Figure ).
    ::从1940年代开始,研究分子和DNA的科学家已经证实了从其他形式的证据中得出的关于进化的结论。他们通过计算物种DNA序列或氨基酸序列之间的差异数量来确定两者之间的关系。这些时钟有时被称为基因钟或进化时钟。差异越少,物种彼此分离并开始演变成不同物种的时间就越少(图 )。

    A chicken and a gorilla will have more differences between their DNA and amino acid sequences than a gorilla and an orangutan. That means the chicken and gorilla had a common ancestor a very long time ago, while the gorilla and orangutan shared a more recent common ancestor. This provides additional evidence that the gorilla and orangutan are more closely related than the gorilla and the chicken. Which pair of organisms would have more molecular differences, a mammal and a , a mammal and a frog , or a mammal and a ?
    ::鸡和大猩猩的DNA和氨基酸序列差异比大猩猩和猩猩要大得多。这意味着鸡和大猩猩很久以前就有一个共同的祖先,而大猩猩和猩猩共有一个最近的共同祖先。 这提供了更多的证据,证明大猩猩和猩猩与大猩猩和鸡的关系更为密切。 哪种生物的分子差异更多,哺乳动物和青蛙,哺乳动物和青蛙,哺乳动物和青蛙?

    On the other hand, may look similar but can have very different DNA sequences and evolutionary ancestry. Which would have more DNA sequences in common, a whale and a horse, or a whale and a shark?
    ::另一方面,可能看起来相似,但DNA序列和进化祖先可能大不相同。 哪一种具有更多共同的DNA序列,鲸鱼和马,或者鲸鱼和鲨鱼?

    A graphic representation of a DNA double helix with colored strands.

    Almost all organisms are made from DNA with the same building blocks. The genomes (all of the genes in an organism) of all mammals are almost identical.
    ::几乎所有生物都是由DNA制成的,有相同的构件。 所有哺乳动物的基因组(所有有机体中的基因)几乎完全相同。

    The genomes , or all the DNA sequences of all the genes of an organism, have been determined for many different organisms. The comparison of genomes provides new information about the relationships among species and how evolution occurs ( Figure ).
    ::基因组,或者所有生物基因的DNA序列,已经为许多不同的生物确定了。 基因组的比较为物种之间的关系和演变过程提供了新的信息(图 ) 。

    Molecular evidence for evolution also includes:
    ::进化的分子证据还包括:

    1. The same biochemical building blocks, such as amino acids and nucleotides , are found in all organisms, from to plants and animals. Recall that amino acids are the building blocks of , and nucleotides are the building blocks of DNA and .
      ::在从植物到动物的所有生物中都发现了同样的生化构件,如氨基酸和核糖酸,回顾氨基酸是...的构件,核酸是DNA和DNA的构件。
    2. DNA and RNA determine the of all organisms.
      ::DNA和RNA确定所有生物。
    3. The similarities and differences between the genomes confirm patterns of evolution.
      ::基因组之间的相似和差异证实了进化模式。

    Map displaying genes on a human chromosome, highlighting genome similarities across species.

    This is a map of the genes on just one of the 46 human chromosomes. How does this region of a chromosome compare to similar regions in other species? Similarities and differences between the genomes (the genetic makeup) of different organisms reveal the relationships between the species.
    ::这是46种人类染色体中的基因图。这个染色体区域与其他物种的类似区域相比如何比较?不同生物的基因组(基因构成)的相似性和差异揭示了物种之间的关系。

    Summary
    ::摘要

    • Molecular clocks are used to determine how closely two species are related by calculating the number of differences between the species' DNA sequences or amino acid sequences.
      ::分子钟用来计算两种物种的DNA序列或氨基酸序列之间的差异,从而确定这两种物种之间的关联程度。
    • Molecular evidence for evolution includes that all living things share the same biochemical building blocks.
      ::进化的分子证据包括所有生物都拥有相同的生化构件。

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    Explore More I
    ::探索更多

    • Genes Tell Us About Evolution - Shape of Life
      ::向基因人讲述进化 - 生命的形状
    1. How is the genetic sequence of an organism like a blueprint of that organism?
      ::生物体的基因序列 如何像这个生物体的蓝图一样?
    2. If two organisms have almost identical sequences for the same gene, are they considered closely related?
      ::如果两种生物对同一基因的序列几乎相同,它们是否认为是密切相关的?
    3. What type of animal have scientists long thought was basal to all other animals? How has genetic analysis affected this view?
      ::科学家们长期认为哪种动物对所有其他动物都是无孔不入的?基因分析是如何影响这种观点的?
    4. How has genetic analysis become quicker than it once was? How has that greatly helped with the search for a basal organism?
      ::基因分析如何变得比以前更快? 这如何极大地帮助了对玄武生物的探索?

    Explore More II
    ::探索更多情况二

    • How Genes Direct Development - Shape of Life
      ::基因如何直接发展-生命的形状
    1. What is a regulatory gene? How might they explain differences between organisms?
      ::什么是监管基因?它们如何解释生物的区别?
    2. What are "hox genes"? What phase of development are they a part of? What organisms have hox genes?
      ::什么是"Hex基因"?它们是什么发展阶段的一部分?什么生物有Hex基因?
    3. If you find a fly with a leg coming out of its head and can identify what happened genetically to cause this, what have you discovered?
      ::如果你发现一只有腿的苍蝇从头部飞出来 并且能辨别出基因原因 你发现了什么?

    Review
    ::回顾

    1. Explain how scientists use a molecular clock to determine relationships between species.
      ::解释科学家如何使用分子钟来确定物种之间的关系。
    2. What is a genome?
      ::什么是基因组?
    3. What two species from the following should have the fewest differences in their genomes: chicken, mouse, duck, gorilla?
      ::下列两种物种的基因组差别应该最小:鸡、老鼠、鸭、大猩猩。
    4. What two species from the following should have the most differences in their genomes: frog, mouse, cow, human?
      ::下列两种物种的基因组差别最大:青蛙、老鼠、奶牛、人类。