Section outline

  • General

    Collapse all Expand all

  • 分解 - 高级

    lesson content

    How do all your cells stay genetically identical?
    ::你所有的细胞如何在基因上保持相同?

    Mitosis, of course. As you can see, mitosis is a multistage process that ensures separation of sister chromatids, and ensures that daughter cells are just like the parent cell .
    ::当然,分裂症。你可以看到,分裂症是一个多阶段的过程,可以确保姐妹染色体分离,并确保女儿细胞与母细胞一样。

    Mitosis
    ::传染病

    Mitosis is the division of the cell's , the final step before two daughter cells are produced. Mitosis begins immediately at the conclusion of interphase , specifically at the end of the G 2 phase. The enters mitosis as it approaches its size limitations. Four distinct phases of mitosis have been recognized: prophase , metaphase , anaphase , and telophase , with each phase merging into the next one ( Figure ). 
    ::细胞分裂是细胞分裂,这是产生两个女儿细胞之前的最后一步。 细胞分裂在中间阶段结束, 特别是G2阶段结束时立即开始。 随着体积限制的接近, 开始分裂。 已经认识到四个不同的分裂阶段: 预阶段、 元阶段、 周期阶段和电讯阶段, 每一个阶段合并到下一个阶段( 图 ) 。

    lesson content

    Mitosis is the phase of the eukaryotic cell cycle that occurs between DNA replication and the formation of two daughter cells. What happens during mitosis? During mitosis, the nucleus divides, paving the way for two cells to be produced after cell division, each with a complete makeup of genetic material.
    ::微粒化是DNA复制和两个女儿细胞形成之间出现的尿道细胞循环的阶段。 在微粒化过程中会发生什么?在微粒化过程中,核分裂为细胞分裂后的两个细胞的生成铺平了道路,每个细胞都有完整的基因材料组成。

    The Phases
    ::阶段

    Prophase
    ::预 期

    Prophase is the first and longest phase of mitosis, see Figure . During prophase, the chromatin (DNA) coils up into visible , each made up of two sister chromatids held together by the centromere . Also during this phase, the nucleolus disappears, and the spindle begins to form from the centrioles . Most eukaryotic cells contain structures known as centrosomes , consisting of a pair of centrioles. During prophase, the centrioles begin to move to opposite ends, or poles, of the cell. As the centrioles migrate, the fiber-like spindle begins to elongate between the centrioles. The spindle is a thin, cage-like structure made out of microtubules . In plant cells, the spindle forms without centrioles. The spindle plays an essential role moving chromosomes and in the separation of sister chromatids.
    ::预期期是分裂症的第一个和最长的阶段,见图。在预期期,染色素(DNA)卷圈会变成可见的,每圈由两姐妹染色体组成,由中子保持在一起。同样在这一阶段,核核素消失,脊椎开始从中子形成。大多数雌激素细胞含有被称为中子体的结构,由一对中子组成。在预期,中子开始移动到细胞的对端或极端。随着中子的迁移,纤维相似的脊椎开始在中子之间拉长。脊椎是一个薄的、类似笼状的结构,由微细胞组成。在植物细胞中,脊椎形式没有中子。脊椎扮演着移动染色体和姐妹染色体分离的重要角色。

    lesson content

    The spindle starts to form during prophase of mitosis. Kinetochores on the spindle attach to the centromeres of sister chromatids.
    ::脊椎在分裂的预发期开始形成。 脊髓灰质炎附于姐妹染色体的中子。

    Preprophase
    ::预 期

    As plant cells have some structural differences compared to an cell, an additional stage prior to prophase is necessary. In plant cells only, prophase is preceded by a preprophase stage. Plant cells have a large central vacuole encompassing the center of the cell. Prior to the division of the nucleus, the nucleus must migrate to the center of the . To accomplish this, the cell forms a phragmosome , a sheet of cytoplasm that bisects the middle of the cell. The phragmosome suspends the cell nucleus in the center of the cell in preparation for prophase. Additionally, during this phase the plane of is established. The accurate control of division planes, which establishes the placement of the future cell wall , is crucial for the correct structure of plant tissues and organs .
    ::由于植物细胞与细胞存在一些结构差异, 需要有一个预期前的附加阶段。 仅在植物细胞中, 预期前先有一个预期阶段。 植物细胞有一个大型中央真空, 包括细胞中心。 在核分裂之前, 核必须迁移到细胞中心 。 要做到这一点, 细胞形成一个长相细胞, 一块双向细胞中间的细胞图谱。 长相细胞将细胞核心的细胞核悬停在细胞中心, 以准备预期阶段 。 此外, 在这一阶段, 建立细胞的平面 。 确定未来细胞墙位置的师机的精确控制对于植物组织和器官的正确结构至关重要 。

    The mitotic spindle also starts to form during preprophase in plant cells. Unlike animal cells, plant cells do not have centrosomes to organize their mitotic spindles. Instead, in these cells, the nuclear envelope acts as a microtubule organizing center (MTOC) for spindle formation. The preprophase spindle forms by self-assembly of microtubules in the cytoplasm surrounding the nuclear envelope.
    ::与动物细胞不同,植物细胞没有分泌细胞来组织其分泌脊椎。相反,在这些细胞中,核包充当了脊椎形成微囊组织中心(MTOC ) 。 通过在核包周围的细胞托盘中自我组装微囊,形成预生脊椎形态。

    Prometaphase
    ::蛋白环

    During early prometaphase , the nuclear membrane disintegrates and microtubule spindles invade the center of the cell. Also during this phase, the spindle attaches to the centromere of each chromatid . Specifically, the spindle attaches to the kinetochore , a structure on the centromere where the spindle fibers attach.
    ::在早期的晶形阶段,核膜分解和微核粒子脊椎侵入细胞中心。同样在这一阶段,脊椎附着于每个色谱的中核。具体地说,脊椎附着于骨骼,这是脊椎纤维附着的中核体上的一个结构。

    Metaphase
    ::相相相 相 相 相 相 相 相 相 相 相 相 相

    During metaphase , the centromeres of the chromosomes line up along the metaphase plate or equatorial plane, in essence the approximate middle of the cell. This orientation of the chromosomes at the equator of the cell helps to ensure proper chromosome separation. This alignment allows the spindle fibers to correctly pull the chromatids to either pole of the cell, resulting in separation of sister chromatids from a chromosome, see Figure .
    ::在元阶段,染色体的中美分沿着元阶段板或赤道平面排列,实质上是细胞的近似中间部分。细胞赤道的染色体的这一方向有助于确保适当的染色体分离。这一对齐使脊椎纤维能够正确地将染色体拉到细胞的两极,导致姐妹染色体与染色体分离,见图。

    lesson content

    Chromosomes, consisting of sister chromatids, line up at the equator (metaphase plate) of the cell during metaphase.
    ::由姐妹染色体组成的染色体,在元阶段时排在细胞赤道(元板板)上。

    Anaphase
    ::相 相 相 相 相 相 相

    Anaphase is the phase in which the sister chromatids separate. The sister chromatids are pulled apart by the shortening of the microtubules of the spindles, similar to the reeling in of a by the shortening of the fishing line. One sister chromatid moves to one pole of the cell, and the other sister chromatid moves to the opposite pole. This process occurs when the proteins that bind sister chromatids together are cleaved, resulting in unattached identical chromosomes, essentially separate daughter chromosomes. These separate chromosomes are pulled apart by shortening spindle fibers, and pulled toward the centrosomes to which they are attached. At the end of anaphase the spindle fibers degrade. At this time, each pole of the cell has a complete set of chromosomes, identical to the amount of at the beginning of G 1 of the .
    ::相片是姊妹染色体分离的阶段。 姊妹染色体被短短的脊椎微图层拉开, 类似于一条钓鱼线的卷线。 一个姊妹染色体移动到细胞的一根柱子上, 另一个姊妹染色体移动到对极。 当将姐妹染色体捆绑在一起的蛋白质被切碎时, 这一过程会发生, 导致未穿透的相同染色体, 基本上分离的女儿染色体。 这些分离的染色体通过缩短脊椎纤维而分离出来, 并拉向它们连接的外形体。 在脉冲的末端, 脊椎纤维会降解。 此时, 每根细胞的染色体都有完整的一套染色体, 与 G1 开始时的染色体数量相同 。

    Telophase
    ::电闪电

    Telophase is essentially the opposite of prophase and prometaphase. The chromosomes begin to unwind back into chromatin in preparation to direct the cell's metabolic activities. A new nucleus forms around each set of chromosomes. This is followed by cytokinesis , the division of the cytoplasm, resulting in two genetically identical cells, ready to enter G 1 of the next cell cycle. The phases of mitosis are summarized in Figure .
    ::色素染色体在准备指导细胞代谢活动时开始回落到染色素中。每组染色体周围都有一个新的核形式。接下来是细胞基质,即细胞顶片的分解,形成两个基因相同的细胞,准备进入下一个细胞周期的G1。图中将概括出细胞分裂的阶段。

    lesson content

    Mitosis in the Eukaryotic Cell Cycle. Mitosis is the multi-phase process in which the nucleus of a eukaryotic cell divides. In this diagram, prometaphase is not included as a separate phase, but incorporated into prophase.
    ::在Eukaryod细胞循环中的消化。 消化是一个多阶段的过程, 其中, eukaryod细胞分裂的核心是多阶段的。 在本图表中, 甲状腺不包含为单独的阶段, 而是包含在预阶段中 。

    lesson content

    This is a representation of dividing plant cells. Cell division in plant cells differs slightly from animal cells as a cell wall must form. Note that most of the cells are in interphase. Can you find examples of the different stages of mitosis?
    ::这是分解植物细胞的表示。 植物细胞的细胞分裂与动物细胞略有不同, 因为细胞壁必须形成。 请注意, 大部分细胞处于中间阶段。 您能找到不同阶段的分裂化的例子吗 ?

    Cytokinesis
    ::阴道

    Cytokinesis is the final step in cell division. It often occurs concurrently with telophase, though it is a separate process. Cytokinesis ( Figure ) differs between plant and animal cells. In animal cells, the plasma membrane pinches inward along the cell's equator until two cells are formed. Specifically, a cleavage furrow containing a contractile ring develops in approximately the middle of the cell (similar to the position of the metaphase plate), essentially pinching off the two nuclei and forming separate cells. In plant cells, a cell plate forms along the cells equator. A new membrane grows along each side of the cell plate, with a new cell wall forming on the outside of each new membrane.
    ::Cytokinesis 是细胞分裂的最后一步。 它经常与电离相同时发生, 尽管它是一个单独的过程。 Cytokinesis (Figure ) 植物和动物细胞之间有差异。 在动物细胞中, 血浆膜在细胞赤道一带内刺, 直到形成两个细胞。 具体地说, 包含一个合同环的乳沟羽毛在细胞的大约中间生长( 类似于元相板的位置 ) , 实质上是捏断两个核, 形成单独的细胞。 在植物细胞中, 在细胞赤道一带形成一个细胞板状。 在细胞板的两侧生长一个新的细胞膜, 在每个新的膜外面形成一个新的细胞墙 。

    At the end of cytokinesis, each daughter cell has a complete copy of the genome of its parent cell. The end of cytokinesis marks the end of the M-phase, the end of one cell cycle, and the beginning of G 1 and interphase of the next cell cycle.
    ::在cytokinesis 结尾处,每个女儿细胞都有其母细胞基因组的完整副本。细胞基因组的结束标志着M阶段的结束,一个细胞循环的结束,G1的开始和下一个细胞循环的中间阶段。

    lesson content

    Cytokinesis is the final stage of eukaryotic cell division. It occurs differently in animal (left) and plant (right) cells.
    ::Cytokinesis 是 eukaryatic 细胞分裂的最后阶段, 在动物( 左) 和植物( 右) 细胞中情况不同 。

    lesson content

    In this electron micrograph of a cell, the formation of two new cells is almost complete, as new membrane grows and divides the parent cell.
    ::在细胞的电子显微图中,两个新细胞的形成已接近完成,因为新的膜在增长,母细胞在分裂。

     

     

     

    Summary
    ::摘要

    • Mitosis is the division of the nucleus.
      ::分裂是核心的分裂。
    • Mitosis is the division of the nucleus; five distinct phases of mitosis have been recognized: prophase, prometaphase, metaphase, anaphase, and telophase.
      ::分裂症是核心的划分;已经认识到分裂症的五个不同阶段:前期、甲状腺、元阶段、前期、后期、后期和调频阶段。
    • Cytokinesis is the division of the cytoplasm. Cytokinesis occurs after mitosis.
      ::Cytokinesis是细胞托盘片的分层。 细胞托kinesis 发生于肾上腺硬化之后。
    • At the end of cytokinesis there are two genetically identical daughter cells.
      ::细胞外科细胞的末端 有两个基因相同的女儿细胞

    Review
    ::回顾

    1. Order the phases of mitosis.
      ::排序阶段的分裂。
    2. Describe the main processes involved in mitosis.
      ::描述与分裂症有关的主要过程。
    3. Differentiate cytokinesis in animal and plant cells.
      ::动物和植物细胞的细胞差异。
    4. Four phases of mitosis: can you describe what happens in each phase?
      ::分裂的四个阶段:你能描述每个阶段发生的情况吗?