章节大纲

  • lesson content

    So Many Cells!
    ::这么多牢房!

    This baby girl has a lot of growing to do before she's as big as her mom. Most of her growth will be the result of . By the time she is an adult, her body will consist of trillions of . Cell division is just one of the stages that all cells go through during their life. This includes cells that are harmful, such as cells. Cancer cells divide more often than normal cells, causing them to  grow out of control. In fact, this is how cancer cells cause illness. In this concept, you will read about how cells divide, what other stages cells go through, and what causes cancer cells to divide out of control and harm the body.
    ::这个女婴在像母亲一样大之前有很多事情要做。 她的成长大部分是 。 当她成年时, 她的身体会由数万亿个细胞组成。 细胞分裂只是所有细胞在其生命中经历的阶段之一。 这包括有害细胞, 如细胞。 癌症细胞比正常细胞更经常地分裂, 导致它们发育失控。 事实上, 癌症细胞是如何引起疾病的。 在这个概念中, 你会读到细胞分裂, 其他细胞经历的是什么, 以及是什么导致癌症细胞 分裂出控制并伤害身体的。

    The  Cell Cycle
    ::细胞周期

    Cell division is just one of several stages that a cell goes through during its lifetime. The cell cycle is a repeating series of events that includes growth, synthesis, and cell division. 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.
    ::细胞分裂只是细胞一生经历的几个阶段之一。 细胞循环是一系列重复的事件,包括生长、合成和细胞分裂。 细胞循环很简单:细胞生长、DNA复制和细胞分裂。 在eukaryotes,细胞循环更为复杂。

    Eukaryotic Cell Cycle
    ::Eukaryod 细胞循环

    The diagram represents the cell cycle of a eukaryotic cell . 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.
    ::图表代表了 eukaryaty 单元格的细胞循环。 正如您所看到的, eukary 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, 执行常规生活过程, 并准备进行分裂 。 这些阶段将在下文讨论 。

    lesson content

    Eukaryotic Cell Cycle. This diagram represents the cell cycle in eukaryotes. The First Gap (G1), Synthesis, and Second Gap (G2) phases make up interphase (I). The mitotic phase includes mitosis and cytokinesis. After the mitotic phase, two cells result.
    ::Eukaryote 细胞循环。 此图表代表了eukaryotes 中的细胞循环。 第一差距( G1)、 合成和第二差距( G2) 阶段组成了中间阶段( I )。 线性阶段包括肾上腺素和细胞基内斯。 在线性阶段之后, 有两个细胞结果 。

    Interphase
    ::间间

    Interphase of the eukaryotic cell cycle can be subdivided into the three phases described below, which are represented in the figure .
    ::eukarye细胞循环的中间阶段可细分为以下三个阶段,如图所示。

    • Growth Phase 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. A cell typically spends most of its life in this phase. This phase is also known as gap phase 1.
      ::增长阶段1(G1):在这一阶段,细胞在进行常规代谢过程的同时迅速生长,还需要进行DNA复制和复制部分DNA,以准备细胞分裂。 细胞通常在其寿命的大部分时间都用于这一阶段。 这一阶段也称为差距阶段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。
    • Growth Phase 2 (G2):  During this phase, the cell makes final preparations to divide. For example, it makes additional proteins and organelles. This phase is also known as gap phase 2.
      ::增长阶段2(G2):在这一阶段,细胞为分解作最后准备,例如,细胞增加蛋白质和器官,这个阶段也称为差距阶段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?细胞循环主要受监管蛋白质控制。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。

    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.
    ::eukaryoy细胞循环中的检查站确保细胞在进入周期下一阶段之前准备就绪。

    • The G1 checkpoint, just before entry into S phase, makes the key decision of whether the cell should divide.
      ::G1检查站就在进入S阶段之前,对小组是否应划分作出关键决定。
    • The S checkpoint determines if the DNA has been replicated properly.
      ::S检查站确定DNA是否已经正确复制。
    • The mito sis  checkpoint ensures that all the are properly aligned before the cell is allowed to divide.
      ::呼吸道疾病检查站确保所有细胞在被允许分解之前均适当对齐。

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

    Cancer is a disease that occurs when the cell cycle is no longer regulated. This happens 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 (see the image ). The rapidly dividing cells take up nutrients and space that normal cells need. This can damage tissues and organs and eventually lead to death.
    ::癌症是一种在细胞循环不再受到监管时发生的疾病,其发生的原因是细胞的DNA遭到破坏。由于接触辐射或有毒化学物质等危险,可能会造成损害。癌症细胞的分裂速度通常比正常细胞的分化速度快得多。它们可能形成一个叫做肿瘤的反常细胞群(见图象 ) 。 快速分裂细胞吸收正常细胞所需的营养和空间。 这会损害组织和器官并最终导致死亡。

    lesson content

    These cells are cancer cells, growing out of control and forming a tumor.
    ::这些细胞是癌症细胞, 发育失控,形成肿瘤。

    Cell Division
    ::单元司

    Cell division is the process in which one cell, called the parent cell , divides to form two new cells, referred to as daughter cells . How this happens depends on whether the cell is prokaryotic or eukaryotic. Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells themselves are simpler. Prokaryotic cells have a single circular chromosome, no nucleus, and few other organelles. Eukaryotic cells, in contrast, have multiple chromosomes contained within a nucleus and many other organelles. All of these cell parts must be duplicated and separated when the cell divides.
    ::细胞分裂是一个叫父细胞的细胞, 分裂成两个新的细胞, 称为女儿细胞。 这取决于细胞是 prokarytology 或 eukaryatic 。 在prokaryotes 中, 细胞分裂比 eukaryotes 更简单, 因为 prokaryates 本身更简单 。 prokaytology 细胞有一个单环染色体, 没有核, 没有其他器官。 相反, Eukaryology 细胞在核和许多其他器官中含有多种染色体。 当细胞分裂时, 所有这些细胞部分都必须重复和分离 。

    Before a eukaryotic cell divides, all of the DNA in the cell’s multiple chromosomes is replicated. Its organelles are also duplicated. Cell division occurs  in two major steps, called mitosis and cytokinesis, both of which are described in greater detail in the concept Mitosis and Cytokinesis.
    ::细胞分裂之前,细胞多种染色体中的所有DNA都会被复制。 细胞的器官也是重复的。 细胞分裂分为两大步,即肾上腺素和细胞外科素。 Mitosis和细胞外科素的概念更详细地描述了这两个步骤。

    • The first step in the division of a eukaryotic cell is mitosis , a multi-phase process in which the nucleus of the cell divides. During mitosis, the nuclear envelope (membrane) breaks down and later reforms. The chromosomes are also sorted and separated to ensure that each daughter cell receives a complete set of chromosomes.
      ::单体细胞分解的第一步是分裂,这是一个多阶段过程,细胞核心在其中分裂。在分裂过程中,核封套(membrane)破裂,后来又进行了改革。染色体也进行了分类和分离,以确保每个女儿细胞都得到一整套染色体。
    • The second major step is cytokinesis . This step, which also occurs in prokaryotic cells, is when the cytoplasm divides, forming two daughter cells. 
      ::第二个主要步骤是细胞基质。这一步骤也是在蛋白质细胞中发生的,就是当细胞托盘分解形成两个女儿细胞时。

    Feature: Human Biology in the News
    ::特著:《新闻》中的人类生物学

    The woman in this mid-1900s photo was named Henrietta Lacks. When she died in 1951 of an unusual form of cervical cancer , she was just 31 years old. A poor, African American tobacco farmer and mother of five, she (or at least her cells) would eventually be called immortal .
    ::19世纪中叶,这张照片中的女人名叫Henrietta Lacks。 1951年她死于一种不寻常的宫颈癌,当时她只有31岁。 贫穷的非裔美国人烟草农和5岁的母亲最终会被称为“不死 ” 。

    Henrietta Lacks sought treatment for her cancer at Johns Hopkins University Hospital at a time when researchers were trying to grow human cells in the lab for medical testing. Despite many attempts, the cells always died before they had undergone many cell divisions. Mrs. Lacks's doctor took a small sample of cells from her tumor without her knowledge and gave them to a Johns Hopkins researcher, who tried to grow them on a culture plate. For the first time in history, human cells grown on a culture plate kept dividing... and dividing and dividing and dividing. Copies of Henrietta's cells  —  called HeLa cells, for her name   —  are still alive today. In fact, there are currently many billions of HeLa cells in laboratories around the world!
    ::Henrietta Lights在约翰·霍普金斯大学医院就癌症寻求治疗,当时研究人员正试图在实验室里种植人体细胞进行医学测试。尽管多次尝试,但细胞总是在细胞分裂之前死亡。拉普斯夫人的医生在她不知情的情况下从她的肿瘤中抽取了少量细胞样本,并将这些细胞交给了一位约翰·霍普金斯研究者,后者试图在文化板上种植这些细胞。历史上第一次,人类细胞在文化板上生长,一直保持分裂和分裂。Henrietta的细胞——以她的名字命名的希拉细胞——今天仍然活着。事实上,目前全世界实验室里有数十亿个希拉细胞!

    Why He nrietta 's cells lived on when other human cells did not is still something of a mystery, but they are clearly extremely hardy and resilient cells. By 1953, when researchers learned of their ability to keep dividing indefinitely, factories were set up to start producing the cells commercially on a large scale for medical research. Since then, HeLa cells have been used in thousands of studies and have made possible hundreds of medical advances. Jonas Salk, for example, used the cells in the early 1950s to test his polio vaccine . Over the decades since then, HeLa cells have been used to make important discoveries in the study of cancer, AIDS, and many other diseases. The cells were even sent to space on early space missions to learn how human cells respond to zero gravity. HeLa cells were also the first human cells ever cloned, and their genes were some of the first ever mapped. It is almost impossible to overestimate the profound importance of HeLa cells to human biology and medicine.
    ::Henrietta的细胞为什么在其它人类细胞并不神秘的情况下生存,但是这些细胞显然极其坚韧和坚韧不拔。1953年,当研究人员了解到他们有能力无限期地分离时,建立了工厂,开始大规模生产细胞,用于医学研究。从那时以来,HeLa细胞被用于数千项研究中,并带来了数百项医学进步。例如,Jonas Salk在1950年代初利用细胞测试其小儿麻痹症疫苗。在那以后的几十年里,HeLa细胞被用来在癌症、艾滋病和许多其他疾病的研究中做出重要发现。这些细胞甚至被送上太空,在早期空间飞行任务中学习人类细胞对零重力的反应。HeLa细胞还是第一个克隆的人类细胞,它们的基因是最早绘制出来的细胞中的一部分。几乎无法高估HeLa细胞对人类生物学和医学的深远重要性。

    You would think that Henrietta's name would be well known in medical history for her unparalleled contributions to biomedical research. However, until 2010, her story was virtually unknown. That year, a science writer named Rebecca Skloot published a nonfiction book about Henrietta Lacks,  The Immortal Life of Henrietta Lacks. Based on a decade of research, the book is riveting, and it became an almost instantaneous best seller. As of 2016, Oprah Winfrey and collaborators planned to make a movie based on the book, and in recent years, numerous articles about Henrietta Lacks have appeared in the press.
    ::您会认为Henrietta的名字在医学史上将因其对生物医学研究的无与伦比的贡献而广为人知。然而,直到2010年,她的故事几乎无人知晓。当年,一位名叫Rebecca Sklout的科学作家出版了一本关于Henrietta Lights的非小说《Henrietta Lesses 》 ( The immortal Life of Henrietta Lesses ) 。 根据十年的研究,这本书充满了活力,成为了近乎瞬间最好的销售者。 截至2016年,Oprah Winfrey 及其合作者计划根据这本书制作一部电影,近年来,媒体上发表了许多关于Henrietta Lacks的文章。

    Ironically, Henrietta herself never knew her cells had been taken, and neither did her family. While her cells were making a lot of money and building scientific careers, her children were living in poverty, too poor to afford medical insurance.  The story of Henrietta Lacks and her immortal cells raises ethical issues about human tissues and who controls them in biomedical research. However, there is no question that Henrietta Lacks deserves far more recognition for her contribution to the advancement of science and medicine.
    ::具有讽刺意味的是,Henrietta自己从不知道她的细胞被夺走,她的家人也不知道。 虽然她的细胞在挣很多钱和建设科学职业,但她的孩子却生活在贫困之中,太穷,买不起医疗保险。 关于Henrietta Lacks及其不朽细胞的故事引起了关于人体组织和谁在生物医学研究中控制这些细胞的伦理问题。 然而,毫无疑问,Henrietta Lacks对科学和医学进步的贡献值得更多承认。

    If you want to learn more about Henrietta Lacks and her immortal cells, read Rebecca Skloot's  The Immortal Life of Henrietta Lacks (or watch the movie, if it is available). You can also watch this documentary about Henrietta Lacks and her immortal cells:
    ::如果您想了解更多关于Henrietta Rights及其不朽细胞的信息,请阅读Rebecca Sklout的《Henrietta Rights的不朽生活》(或者看电影,如果有的话,看电影)。您也可以看关于Henrietta Rights及其不朽细胞的纪录片:

     Summary
    ::摘要

    • The cell cycle is a repeating series of events that includes growth, DNA synthesis, and cell division. The cyc l e  is more complicated in eukaryotic than prokaryotic cells.
      ::细胞循环是一系列重复性事件,包括生长、DNA合成和细胞分裂。 在尿道细胞中,细胞循环比在蛋白细胞中更为复杂。
    • In a eukaryotic cell, the cell cycle has two major phases: mitotic phase and interphase. During mitotic phase, first the nucleus and then the cytoplasm divide. During interphase, the cell grows, performs routine life processes, and prepares to divide.
      ::在eukaryatic细胞中,细胞循环有两个主要阶段:线性阶段和间段。在线性阶段,先是核,然后是细胞顶层分裂。在间歇阶段,细胞生长,进行常规生活过程,并准备分裂。
    • The cell cycle is controlled mainly by regulatory proteins that signal 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. There are a number of main checkpoints in the regulation of the cell cycle.
      ::细胞循环主要受监管蛋白质控制,这些蛋白质指示细胞开始或推迟周期的下一阶段,确保细胞在前进之前完成前一个阶段,在管理细胞循环方面有若干主要检查点。
    • Cancer is a disease that occurs when the cell cycle is no longer regulated, often because the cell's DNA has become damaged. Cancerous cells grow out of control 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,经常是因为细胞的DNA受损。 癌症细胞发展失控,并可能形成被称为肿瘤的异常细胞。
    • The cell division phase of the cell cycle in a eukaryotic cell occurs in two major steps: mitosis — when the nucleus divides — and cytokinesis, when the cytoplasm divides and two daughter cells form.
      ::单体细胞细胞循环的细胞分裂阶段分为两个主要步骤:细胞分裂——当核分裂时——和细胞细胞——当细胞细胞分裂和两个子细胞形成时。

    Review
    ::回顾

    1. What are the two mai n phases of the cell cycle in a eukaryotic cell?
    ::1. 单体细胞细胞循环的两个主要阶段是什么?

    2. Describe the three phases of interphase in a eukaryotic cell.
    ::2. 描述产卵细胞间段的三个阶段。

    3. Explain how the cell cycle is controlled.
    ::3. 解释如何控制细胞循环。

    4. How is cancer related to the cell cycle?
    ::4. 癌症与细胞循环的关系如何?

    5. Explain why cell division is more complex in eukaryotic than prokaryotic cells.
    ::5. 解释为什么细胞分裂在表情细胞中比在表情细胞中更为复杂。

    6. What are the two major steps of cell division in a eukaryotic cell ?
    ::6. 单体细胞分裂的两个主要步骤是什么?

    7. In which phase of the eukaryotic cell cycle do cells typically spend most of their lives?
    ::7. 细胞在哪个阶段的尿道细胞循环期通常大部分时间都花在细胞的一生中?

    8. Using a technique called flow cytometry, scientists can distinguish between cells with the normal amount of DNA and those that contain twice the normal amount of DNA as they go through the cell cycle. Which phases of the cell cycle will have cells with twice the amount of DNA? Explain your answer.
    ::8. 科学家使用一种称为流动细胞测量的技术,可以区分具有正常DNA数量的细胞和那些在通过细胞循环时含有正常DNA数量两倍的细胞。细胞循环的哪个阶段的细胞将拥有DNA数量两倍的细胞?解释你的答案。

    9. If there is damage to a gene that encodes for a cell cycle's regulatory protein, what do you think might happen? Explain your answer.
    ::9. 如果细胞循环调节蛋白质编码的基因受到损害,你认为会发生什么?解释你的答复。

    10. True or False:  A cell fully splits into two daughter cells during part of interphase.
    ::10. 真实或假:一个牢房在间歇部分期间完全分裂成两个女儿牢房。

    11. True or False:  Cells go into G0 if they do not pass the G1 checkpoint.
    ::11. 真实或假:牢房如不通过G1检查站,则进入G0。

    12. True or False:  Cytokinesis occurs in both prokaryotes and eukaryotes.
    ::12. 真实或假的:阴道切除在直肠和eukaryotes都发生。

    13. In which phase within interphase  does  the cell make final preparations to divide?
    ::13. 在中间阶段的哪个阶段,小组最后准备分拆?

    a. mitosis
    ::a. 分裂症

    b. cytokinesis
    ::b. 细胞基系

    c. G2
    ::c. G2

    d. S
    ::d. S.

     

    14. What were scientists trying to do when they took tumor cells from Henrietta Lacks? Why did they specifically use tumor cells to try to achieve their goal?
    ::14. 当科学家从亨丽埃塔省取取肿瘤细胞时,他们想做什么?为什么他们专门使用肿瘤细胞来达到他们的目标?

    Explore More
    ::探索更多

    Watch the video below to learn more about cell cycle checkpoints. 
    ::更多了解细胞循环检查站。

     

    The video below discusses the cell cycle and how it relates to cancer.  
    ::以下影片讨论细胞循环及其与癌症的关系。