Section outline

  • General

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  • 单元格周期

    What you will learn
    ::你会学到什么

    • Phases in the cell cycle of eukaryotes 
      ::eukaryotes 细胞循环中的相位
    • How the cell cycle is regulated
      ::如何管理细胞循环

    Life cycle of a frog showing stages: eggs, embryos, tadpoles, and adult frog.

     

    Do cells have a life cycle?
    ::细胞有生命周期吗?

    Yes, just like a frog passes through different phases from a tadpole to an adult frog, there are a series of phases in a cell's life as it gets ready to divide. The sequence of phases leading up to and then ending with cell division itself is called the cell cycle.
    ::是的,就像青蛙通过从到成年青蛙的不同阶段一样,细胞生命中存在一系列阶段,随着细胞的分化准备就绪。在细胞分裂之前和之后的阶段序列本身被称为细胞循环。

    The Cell Cycle
    ::细胞周期

    The cell cycle is a repeating series of events that includes growth, synthesis, and cell division. The eukaryotic cell spends most of its "life" in interphase of the cell cycle, which can be subdivided into the three phases, G1, S and G2. Cell division is just one of several stages that a goes through during its lifetime. The cell cycle in is quite simple: the cell grows, its DNA replicates, and the cell divides. In eukaryotes , the cell cycle is more complicated.
    ::细胞循环是一系列重复的事件, 包括生长、 合成和细胞分裂。 eukaryatic 细胞循环的大部分“ 寿命” 都花在细胞循环的中间阶段, 可以细分为三个阶段, G1, S 和 G2 。 细胞分裂只是生命期内经历的几个阶段之一。 细胞循环非常简单: 细胞生长, DNA复制, 细胞分裂。 在 eukaryotes 中, 细胞循环更为复杂 。

    The Eukaryotic Cell Cycle
    ::Eukaryotoc 细胞周期

    The cell cycle of a eukaryotic cell is represented below. As you can see, the eukaryotic cell cycle has several phases. The mitotic phase (M) actually includes both and cytokinesis . This is when the and then the cytoplasm divide. The other three phases (G1, S, and G2) are generally grouped together as interphase . During interphase, the cell grows, performs routine life processes, and prepares to divide. These phases are discussed below. 
    ::eukaryatic 单元格的细胞循环如下。 正如您所看到的, eukaryatic 细胞循环有几个阶段。 单体细胞( M) 阶段实际上包括了两者, 也包括了细胞基质。 这是细胞基体分裂的时间和时间。 其他三个阶段( G1, S 和 G2) 通常被分组为间段 。 在中间段, 细胞生长、 进行常规生活过程, 并准备分裂。 这些阶段将在下文中讨论 。

    Interphase
    ::间间

    Interphase of the eukaryotic cell cycle can be subdivided into the following three phases:
    ::eukaryy细胞循环的间隙可细分为以下三个阶段:

    • G ap 1 (G1): during this phase, the cell grows rapidly, while performing routine metabolic processes. It also makes needed for DNA replication and copies some of its in preparation for cell division. This phase is sometimes referred to as Growth Phase 1.
      ::差距1(G1):在这一阶段,细胞迅速生长,同时进行常规代谢过程,还需要DNA复制和复制部分DNA,以准备细胞分裂,这一阶段有时被称为增长阶段1。
    • Synthesis Phase (S): during this phase, the cell’s DNA is copied in the process of DNA replication .
      ::合成阶段:在这一阶段,在复制DNA的过程中复制细胞的DNA。
    • G ap 2 (G2): during this phase, the cell makes final preparations to divide. For example, it makes additional proteins and organelles. This phase is sometimes referred to as G rowth Phase 2.
      ::差距2(G2):在这一阶段,细胞为分裂作最后准备。例如,细胞产生额外的蛋白质和有机物。这个阶段有时被称为增长阶段2。

    Control of the Cell Cycle
    ::控制细胞循环

    If the cell cycle occurred without regulation, cells might go from one phase to the next before they were ready. What controls the cell cycle? How does the cell know when to grow, synthesize DNA, and divide? The cell cycle is controlled mainly by regulatory proteins . These proteins control the cycle by signaling the cell to either start or delay the next phase of the cycle. They ensure that the cell completes the previous phase before moving on. Regulatory proteins control the cell cycle at key checkpoints, which are shown in the  Figure . There are a number of main checkpoints.
    ::如果细胞循环发生没有监管,细胞周期可能会在准备之前从一个阶段到下一个阶段。什么控制细胞循环?细胞循环?细胞循环如何知道何时生长、合成DNA和分裂?细胞循环主要由监管蛋白质控制。这些蛋白质通过信号细胞控制周期,要么开始要么推迟周期的下一个阶段。它们确保细胞在前进之前完成上一个阶段。监管蛋白质控制关键检查站的细胞循环,如图所示。有一些主要检查站。

    Phases of the cell cycle and key checkpoints for regulation.
    Checkpoints in the eukaryotic cell cycle ensure that the cell is ready to proceed before it moves on to the next phase of the cycle.
    1. Cell growth checkpoint (G1 checkpoint): The G1 checkpoint, just before entry into S phase, makes the key decision of whether the cell should divide.
      ::细胞生长检查站(G1检查站):G1检查站在进入S阶段之前,就主要决定该牢房是否应分开。
    2. DNA synthesis checkpoint (S checkpoint): The S checkpoint determines if the DNA has been replicated properly.
      ::DNA合成检查站(S检查站):S检查站确定DNA是否得到适当复制。
    3. Mitosis checkpoint (Mitotic spindle checkpoint): The mitotic spindle checkpoint occurs at the point in metaphase where all the should have aligned at the mitotic plate.
      ::防疫检查站(防水脊椎检查站):防水脊椎检查站发生于元阶段,所有人员都应在防水板上对齐。

    Cancer and the Cell Cycle
    ::癌症和细胞周期

    is a disease that occurs when the cell cycle is no longer regulated. This may happen because a cell’s DNA becomes damaged. Damage can occur due to exposure to hazards such as radiation or toxic chemicals. Cancerous cells generally divide much faster than normal cells. They may form a mass of abnormal cells called a tumor . The rapidly dividing cells take up nutrients and space that normal cells need. This can damage tissues and organs and eventually lead to death.   
    ::这是一种在细胞循环不再受监管时发生的疾病,可能因为细胞的DNA受损而发生。由于接触辐射或有毒化学物质等危险,损害可能发生。癌症细胞通常比正常细胞的分化速度快得多。它们可能形成被称为肿瘤的反常细胞群。快速分裂细胞群吸收正常细胞需要的营养和空间。这会损害组织和器官并最终导致死亡。

     

     

     

    DID YOU KNOW?
    A group of proteins called cyclins along with known as cyclin-dependent kinases regulate the cell cycle checkpoints. The concentration of cyclin proteins varies during the cell cycle. 
     

    Summary
    ::摘要

    • The cell cycle is a repeating series of events that cells go through. It includes growth, DNA synthesis, and cell division. In eukaryotic cells, there are two growth phases, and cell division includes mitosis and cytokinesi s.
      ::细胞循环是细胞经历的一系列重复事件。 它包括生长、DNA合成和细胞分裂。 在尿液细胞中,细胞循环有两个生长阶段,细胞分裂包括肾硬化和细胞基离子。
    • The cell cycle is controlled by regulatory proteins at three key checkpoints in the cycle. The proteins signal the cell to either start or delay the next phase of the cycle.
      ::细胞循环由循环中三个关键检查站的调节蛋白质控制,蛋白质表示细胞要么开始,要么推迟周期的下一个阶段。
    • Cancer is a disease that occurs when the cell cycle is no longer regulated. Cancer cells grow rapidly and may form a mass of abnormal cells called a tumor.
      ::癌症是一种在细胞循环不再受管制时发生的疾病,癌症细胞迅速生长,并可能形成被称为肿瘤的异常细胞。

    Review
    ::回顾

    1. Identify the phases of the eukaryotic cell cycle.
      ::确定欧元细胞循环的各个阶段。
    2. What happens during interphase?
      ::中继阶段会发生什么事?
    3. Define cancer.
      ::给癌症下定义
    4. Cells go through a series of events that include growth, DNA synthesis, and cell division. Why are these events best represented by a cycle diagram?
      ::细胞经历了一系列事件,其中包括生长、DNA合成和细胞分裂。 为什么这些事件最好用循环图来表示?
    5. Explain how the cell cycle is regulated.
      ::解释如何管理细胞循环。
    6. Why is DNA replication essential to the cell cycle?
      ::为什么DNA复制对细胞循环至关重要?