细胞周期

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

Yes, just like a butterfly passes through different phases, such as caterpillar, chrysalis, and adult butterfly, 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,就像蝴蝶通过不同的阶段,比如毛毛虫、菊和成年蝴蝶, 细胞生命中有一系列的阶段,随着细胞的分化准备就绪。 细胞分裂之前和之后的阶段的顺序被称为细胞循环。

Cell Cycle
::单元格周期

The process of cell division in  eukaryotic cells  is carefully controlled. The  cell cycle  ( Figure   ) is the life cycle of an eukaryotic cell, with cell division at the end of the cycle. Like a human life cycle, which is made up of different phases, like  childhood ,  adolescence , and  , the cell cycle also occurs in a series of phases. The   cycle begins with the formation of a  zygote  from the fusion of a male and female sex cell ( gamete ).
::细胞循环(图)是细胞循环的生命周期,在循环结束时是细胞分裂,与人类生命周期一样,细胞循环由不同阶段组成,如童年、青春期和青少年,细胞循环也分一系列阶段进行,从男女性别细胞(gamete)的融合形成zygote开始。

The steps of the cell cycle can be divided into two main components:  interphase  and the  mitotic phase .  Interphase  is the stage when the cell mostly performs its “everyday” functions. For example, it is when a   cell does what a kidney cell is supposed to do. The cell also gets ready to divide during this time. The cell divides during the mitotic phase, which consists of   and  cytokinesis .
::细胞循环的阶梯可以分为两个主要部分:中间和线性阶段。中间阶段是细胞主要履行“日常”功能的阶段。例如,它是细胞做肾脏细胞应该做的事情。在此期间,细胞也准备进行分裂。在线性阶段,细胞分裂由细胞组成,细胞细胞分裂。

Most of the cell cycle consists of interphase, the time between cell divisions. Interphase can be divided into three stages:
::大部分细胞循环由间段、细胞分裂之间的时间组成。 间段可分为三个阶段:

1. The first growth phase (G1): During the G1 stage, the cell doubles in size and doubles the number of  .
   ::第一个增长阶段(G1):在G1阶段,细胞体积翻倍,数量翻倍。

1. The synthesis phase (S): The   is replicated during this phase. In other words, an identical copy of all the cell’s DNA is made. This ensures that each new cell has a set of  genetic material  identical to that of the parental cell. This process is called  DNA replication .
   ::合成阶段(S):合成阶段(S):在这一阶段复制。换句话说,对细胞的所有DNA都做了相同的复制件。这确保了每个新细胞都有一套与母细胞相同的基因材料。这个过程被称为DNA复制。

1. The second growth phase (G2):  Proteins  are synthesized that will help the cell divide. At the end of interphase, the cell is ready to enter mitosis.
   ::第二个增长阶段(G2):对蛋白质进行合成,以帮助细胞分裂。在中间阶段结束时,细胞可以进入分裂状态。

During  mitosis , the   divides as the  chromosomes  are equally separated. One nucleus becomes two nuclei, each with an identical set of  chromosomes . Mitosis is followed by  cytokinesis , when the  cytoplasm  divides, resulting in two cells. After cytokinesis, cell division is complete. The one  parent cell  (the dividing cell) forms two genetically identical  daughter cells  (the cells that divide from the parent cell). The term "genetically identical" means that each cell has an identical set of DNA, and this DNA is also identical to that of the parent cell. If the cell cycle is not carefully controlled, it can cause a disease called   in which the cells divide out of control. A  tumor  can result from this kind of growth.
::在细胞分裂期间, 染色体的分界线是相等的。 一个核变成两个核, 每个核都具有相同的染色体。 细胞分裂后, 细胞分裂后, 细胞分裂产生两个细胞。 在细胞分裂后, 细胞分裂是完整的。 一个母细胞( 分裂细胞) 形成两个遗传上相同的女儿细胞( 与母细胞分开的细胞) 。 “ 遗传上相同的” 表示每个细胞都有一套相同的DNA, 这个DNA也与母细胞相同。 如果细胞循环不小心控制, 它可能造成细胞分裂出控制的疾病。 肿瘤可以由这种生长产生 。

Summary
::摘要

• The cell cycle describes the "life" of a cell.
  ::细胞循环描述细胞的“生命”。

• Interphase, the stage of the cell cycle when the cell, preparing to divide, is divided into the G1, S, and G2 stages.
  ::中间阶段,即细胞周期的阶段,当准备分裂的细胞被分为G1、S和G2级时。

• The nucleus divides during mitosis, and the cytoplasm divides during cytokinesis.
  ::细胞硬化过程中的核分裂 细胞硬化过程中的核分裂 细胞硬化过程中的核分裂

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。

• Cell Divisions and the Cell Cycle  - 
  
  ::单元格分区和单元格周期 -- --

1. What are the major phases of the cell cycle?
   ::细胞循环的主要阶段是什么?

1. Why do you think it is important for a cell to grow before it replicates its DNA? Be as specific as you can in your answer.
   ::为什么你认为细胞在复制DNA之前必须成长起来? 在回答时要尽可能具体。

1. What happens during the S phase of the cell cycle?
   ::在细胞循环的S阶段会发生什么情况?

1. What happens during mitosis?
   ::精神分裂时会怎样?

1. What is the function of spindle fibers? Where do they attach?
   ::脊椎纤维的功能是什么?它们附着在哪里?

1. What is the function of meiosis?
   ::肾上腺素的功能是什么?

Review
::回顾

1. What is the cell cycle?
   ::什么是细胞循环?

1. What are the two main components of the cell cycle?
   ::细胞循环的两个主要组成部分是什么?

1. What occurs during interphase?
   ::中间阶段发生什么了?

1. What are the three stages of interphase?
   ::中间阶段的三个阶段是什么?

1. What is the main purpose of the S phase?
   ::S阶段的主要目的是什么?

1. Describe the main events of the mitotic phase.
   ::描述排他阶段的主要事件。

1. Define cancer.
   ::给癌症下定义