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  • DNA 结构和复制

    A person operating a copier, symbolizing the concept of DNA replication.

    Does copy itself?
    ::复制自己吗?

    Yes, your DNA needs to copy itself every time a new cell is created. The new cell needs to have DNA exactly like the rest of your cells. Otherwise, that cell might malfunction. That's why it's important that the process of copying DNA, called DNA replication , is very accurate.
    ::是的,每次创建新细胞时,你的DNA都需要复制自己。新细胞需要的DNA和你的细胞的其余部分完全一样。 否则,这个细胞可能会出故障。这就是为什么复制DNA的过程,叫做DNA复制, 一定要非常精确的原因。

    DNA Replication
    ::DNA复制

    DNA must replicate (copy) itself so that each resulting cell after and has the same DNA as the parent cell . All these cells, the parent cell and the two new daughter cells , are genetically identical.
    ::DNA必须复制(复制)它本身,这样每个生成的细胞之后都具有与母细胞相同的DNA。 所有这些细胞、母细胞和两个新的女儿细胞在基因上都是一样的。

    DNA replication occurs during the S phase (the Synthesis phase) of the , before mitosis and cell division. The base pairing rules are crucial for the process of replication . DNA replication occurs when DNA is copied to form an identical molecule of DNA.
    ::DNA复制发生在...的S阶段(合成阶段),在分裂和细胞分裂之前。基底配对规则对于复制过程至关重要。DNA复制在复制DNA以形成相同的DNA分子时发生。

    The general steps involved in DNA replication are as follows:
    ::DNA复制所涉的一般步骤如下:

    1. The DNA helix unwinds like a zipper as the bonds between the base pairs are broken. The enzyme DNA Helicase is involved in breaking these bonds.
      ::DNA螺旋藻像拉链一样松开,因为基底两对之间的链条被打破。 酶DNA Helicase参与打破这些链条。
    2. The two single strands of DNA then each serve as a template for a new stand to be created. Using DNA as a template means that on the new strand, the bases are placed in the correct order because of the base pairing rules. Recall that A and T are complementary bases, as are G and C. As a template strand is read, the new strand is created. If ATGCCA is on the "template strand," then TACGGT will be on the new DNA strand. The enzyme DNA Polymerase reads the template and builds the new strand of DNA.
      ::DNA的两条单线, 然后各作为新立方体的模板。 使用DNA作为模板意味着在新立方体上, 基底配对规则使基底处于正确的顺序。 回顾A和T是互补的基点, 如G和C。 当阅读模板时, 将创建新立方体。 如果 ATGCCA 位于“ 板块 ” 上, 那么TACGGT 将位于新的DNA线上。 酶DNA聚合酶读取模板, 并构建新的DNA线 。
    3. The new set of nucleotides then join together to form a new strand of DNA. The process results in two DNA molecules, each with one old strand and one new strand of DNA.
      ::新的核糖核酸元素组合在一起形成新的DNA链。这一过程产生两个DNA分子,每个分子都有一条旧的DNA线和一条新的DNA线。

    This process is known as semiconservative replication because one strand is conserved (kept the same) in each new DNA molecule ( Figure ).
    ::这个过程被称为半保守性复制,因为每一新DNA分子(图)中都有一股被保存(被保留在相同的位置上)。

    DNA strands unzipping and base pairing in replication process.

    DNA replication occurs when the DNA strands “unzip,” and the original strands of DNA serve as a template for new nucleotides to join and form a new strand.
    ::当DNA链“unzip”和最初的DNA线成为新核糖核酸加入并形成新线的样板时,就会出现DNA复制。

    Summary
    ::摘要

    • During DNA replication, the DNA helix unwinds and the two single strands of DNA then each serve as a template for a new stand to be created.
      ::在DNA复制过程中,DNA螺旋松风和DNA的两条单线,然后各作为将创建的新立方体的模板。
    • DNA replication is semi-conservative: the new DNA molecule consists of half of the parent DNA molecule.
      ::DNA的复制是半保守性的:新的DNA分子由父DNA分子的一半组成。

    Explore More
    ::探索更多

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

    • DNA replication at (7:47)
      ::在(7:47)复制DNA
    1. What protein molecules does DNA wrap around to form a nucleosome?
      ::DNA环绕着什么蛋白质分子 形成核核素?
    2. What makes up chromatin?
      ::什么构成染色素?
    3. When can you see chromosomes in a cell?
      ::你什么时候能看到牢房里的染色体?
    4. Are both strands of DNA copied continuously during replication? Explain your answer.
      ::复制时是否不断复制DNA的两部分? 请解释您的答复 。

    Review
    ::回顾

    1. Describe how DNA is replicated.
      ::说明DNA是如何复制的。
    2. Explain why DNA replication is sometimes called semiconservative.
      ::解释为什么DNA复制有时被称为半保守性。