Name: cell division: mitosis and cytokinesis
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 35 s
Channel: JoVE

有丝分裂是一种细胞分裂方式，其中细胞的遗传物质被分配到两个子细胞中。&#160;
首先，在前期，核内的染色质凝聚成X形的染色体，这些染色体由在着丝粒连接处相连的姐妹染色单体对组成。
与此同时，中心体向细胞的两侧相对移动。随着这一过程的进行，微管杆状结构开始从每个中心体向外生长，形成网状的纺锤体装置。
接着，在前中期，核膜溶解，着丝粒两侧出现称为&#160;动粒的蛋白质结构，每条染色单体各有一个动粒。
一旦这些动粒形成，延伸的内部微管便会附着其上，每条姐妹染色单体分别与细胞的不同一极相连。
在&#160; 中期，纺锤体装置将染色体重新排列，使其沿细胞赤道面整齐排列成一行。
在后期，着丝粒附着的微管缩短，姐妹染色单体被拉向两极。这些微管动力学变化及其他微管活动也导致细胞伸长。
在末期，纺锤体结构解体，染色单体松解，核膜重新形成。
最后，细胞通过胞质分裂完成细胞质的分离，形成一对在遗传上与其前体完全相同的子细胞。

<ol>
	<li>Guertin、David A.、Susanne Trautmann 和 Dannel McCollum。"真核生物中的胞质分裂。"微生物学。分子生物学修订版 66，第 2 期（2002 年 6 月 1 日）:155-78。</li>
</ol>

有丝分裂与胞质分裂

Mitosis And Cytokinesis

在真核生物中，细胞分裂周期被划分为不同的、协调的细胞过程，包括细胞生长、DNA 复制/染色体复制、染色体分配给子细胞，以及最后的细胞分裂。细胞周期受到其调节系统以及影响细胞增殖的细胞外信号的严格调控。

细胞周期的过程大约需要24小时（在典型的人类细胞中），并分为两个主要的可区分阶段。 第一阶段是DNA复制，即间期的S阶段。 第二阶段是有丝分裂 (M) 阶段，涉及将复制的染色体分离成两个新的细胞核（有丝分裂）和细胞质分裂（细胞分裂）。 这两个阶段由间隔（G1 和 G2 间隙）隔开，在此期间细胞准备复制和分裂。

有丝分裂的过程

有丝分裂可分为五个不同的阶段：前期、前期、中期、后期和末期。细胞分裂开始于后期或末期（取决于细胞），是 M 期的一部分，但不是有丝分裂的一部分。

前期

当细胞进入有丝分裂时，其复制的染色体开始凝聚，并在称为凝聚素的蛋白质的帮助下变成可见的线状结构。纺锤体装置开始在S阶段复制的中心体之间形成，并迁移到细胞的相反两极。纺锤体由称为微管的纤维状结构组成，这些微管由微管蛋白单体组成。纺锤体微管开始向凝聚的染色体延伸。核仁是细胞核中产生核糖体的一个组成部分，核仁的消失，预示着细胞核即将解体。

前中期

在前中期，纺锤体的微管丝继续生长，染色体完成凝聚。核膜完全分解，释放染色体。一些微管附着在释放的染色体上，与一种称为动粒的蛋白质结构结合，该结构存在于每对姐妹染色单体的着丝粒上。来自相反两极的纺锤体微管附着在动粒上并捕获凝聚的姐妹染色单体对。不附着在染色体上的纺锤体微管（极微管和星体微管）有助于将纺锤体推开并将纺锤体两极固定在细胞膜上。

中期

纺锤体微管将每对完全凝聚的姐妹染色单体沿着细胞的赤道（在中期板）对齐。 细胞现在已准备好分裂了。

后期

来自相反纺锤体极的微管附着在动粒结构上，缩短并分离着丝粒处的姐妹染色单体。将染色单体固定在一起的粘合蛋白现在分解了。缩短的动粒微管导致这对染色单体（现在称为染色体）迁移到相反的极。

末期

一旦染色体到达细胞的相对两极，它们就会解压缩并展开，形成染色质。纺锤体微管丝解聚成微管蛋白单体，这些单体随后在子细胞中用作细胞骨架元素。核膜在每组染色体周围重新组装。

胞质分裂

在动物细胞的胞质分裂过程中，肌动蛋白纤维在质膜中形成收缩环，从而形成一个分裂沟，最终将细胞挤压成两半。在植物细胞中，来自高尔基体的囊泡携带葡萄糖、酶和结构蛋白，在原中期板的位置结合形成新的细胞板。随着细胞板的增长，它与两侧的质膜融合，将细胞分成两部分。

有丝分裂现已完成，产生了两个与亲本细胞相同的子细胞。在大多数人类细胞中，细胞周期大约为24 小时，有丝分裂占其中的一小时。

在真核生物中，细胞分裂周期被划分为一系列明确且协调的细胞过程，包括细胞生长、DNA复制/染色体……

Education

教育

JoVE Core

Anatomy and Physiology

解剖学与生理学

Unit 1

第 1 单元

Essential Cellular Processes

细胞基本过程

KEY TERMS AND CONCEPTS

关键术语与概念

有丝分裂和胞质分裂

cell division: mitosis and cytokinesis

Cell division depends on mitosis and cytokinesis. Mitosis is the stage when the cell’s nucleus divides and the copied chromosomes are separated into two sets. Cytokinesis is the step that follows and splits the cell into two daughter cells.

These two processes work together to make sure each new cell receives genetic material and its own cytoplasm. Mitosis keeps the chromosome sets organized, while cytokinesis finishes the division of the whole cell. Together, they create two separate cells from one starting cell.

Cell Division: Mitosis and Cytokinesis

the central dogma

Central Dogma: DNA to Protein

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function. DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein. Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules...

replication in eukaryotes

Eukaryotic DNA Copying at the Replication Fork

Eukaryotic DNA copying happens at replication forks, where the two DNA strands separate and new strands are built. This process lets a cell make an exact copy of its genetic material before it divides. The transcript explains that eukaryotic replication follows the same basic steps seen in other DNA replication systems, but it takes place in cells with a nucleus. The replication machinery works on each separated strand as a template, so the new DNA matches the original sequence. This topic is...

types of rna

RNA Types in Gene Expression

RNA types play different roles in gene expression. RNA, or ribonucleic acid, helps carry and use genetic information in cells. The main types discussed here are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA, or mRNA, carries the genetic code from DNA to the ribosome. The ribosome is the site where proteins are made. Ribosomal RNA, or rRNA, is a key part of the ribosome itself. Transfer RNA, or tRNA, brings the correct amino acids to the ribosome during protein building. These...

transcription

Transcription and RNA Synthesis

Transcription is the process of making RNA from a DNA template. It is a key step in gene expression, because cells use the DNA sequence to build an RNA copy that can carry the message forward. During transcription, RNA polymerase binds to DNA and reads one strand as the template. The enzyme links RNA nucleotides together in the correct order to form a growing RNA molecule. This copying step does not make DNA; it produces RNA. The transcript focuses on the central idea of transcription as DNA...

translation

Translation: mRNA to Protein

Translation is the step in gene expression where ribosomes use messenger RNA, or mRNA, to build a protein. The mRNA sequence carries the instructions copied from DNA. During translation, those instructions are read in order so the cell can make a specific chain of amino acids. This process depends on the ribosome and transfer RNA, or tRNA. The ribosome reads the mRNA, and tRNA brings the matching amino acids. As the chain grows, the amino acids are linked together to form a polypeptide, which...

regulation of expression at multiple steps

regulation-of-expression-at-multiple-steps

How Cells Control Gene Expression

Cells control gene expression at several stages, from making RNA to building protein. These checkpoints include transcription, RNA processing, RNA localization, and translation. Together, they help decide when a gene is used and whether a protein is made. Transcription is controlled by regulatory proteins. Transcription factors, activators, and repressors can start or slow the transcription of genes. After transcription, the cell makes a precursor RNA, also called pre-mRNA. Pre-mRNA must be...

what is the cell cycle?

Cell Cycle Stages in Cell Growth

The cell cycle is the process that controls cell growth and division. It explains how one cell makes two new cells. This process helps cells grow and reproduce.

interphase

Interphase and Cell Growth

Interphase is the part of the cell cycle when a cell grows and prepares to divide. It is a major stage of the cell cycle, and it comes before cell division begins. During interphase, the cell carries out its normal functions. It also copies its DNA so each new cell can receive a full set of genetic material. The cell may also build up the materials it needs for division. Interphase is not a single step. It includes phases such as G1, S, and G2, which help the cell grow, copy DNA, and get...

mitosis and cytokinesis

Cell division depends on mitosis and cytokinesis. Mitosis is the stage when the cell’s nucleus divides and the copied chromosomes are separated into two sets. Cytokinesis is the step that follows and splits the cell into two daughter cells. These two processes work together to make sure each new cell receives genetic material and its own cytoplasm. Mitosis keeps the chromosome sets organized, while cytokinesis finishes the division of the whole cell. Together, they create two separate cells...

the cell cycle control system

Cell Cycle Checkpoints and Cyclin Control

The cell cycle is controlled by checkpoints that help a cell move from one phase to the next and begin mitosis. This control system uses internal regulatory molecules and outside signals to send stop or advance instructions. It makes sure each step is finished before the cell moves forward. Cyclins and cyclin-dependent kinases, or Cdks, are the main regulators of the cell cycle. They act during the G1, G2, and M phases. These regulators work at specific checkpoints to keep cell division...

molecular factors affecting cell division

molecular-factors-affecting-cell-division

Cell Cycle Regulators That Control Division

Cell division is controlled by outside signals and by internal cell cycle regulators. Nearby cell death can encourage division, and human growth hormone (hGH) can also promote it. In contrast, too little hGH or crowded cells can slow or stop division. Inside the cell, regulator molecules help each stage finish correctly before the next stage begins. Some regulators act directly on the cycle, while others affect the activity or production of other regulatory proteins. These molecules can either...

what is meiosis?

Meiosis and the Formation of Gametes

Meiosis is the cell division process that forms gametes, or sex cells. It reduces the chromosome number so offspring can inherit the correct amount of genetic material. This process includes two successive divisions. First, one cell divides, and then the resulting cells divide again. These steps separate the genetic material in a controlled way. Meiosis helps explain how sexual reproduction passes traits from one generation to the next. It is a key topic in high school biology because it...

overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways and responses help cells communicate and react to changes. Cells send signals to one another, and those signals can trigger a specific response in the target cell. A signal usually begins when a signaling molecule reaches a cell with the right receptor, which is a protein that receives the message. The receptor helps the cell recognize the signal and start the communication process. Inside the cell, the message can move through a signaling pathway. This pathway passes...

types of signaling molecules

Chemical Messengers in Cell Signaling

Chemical messengers help cells communicate during signaling. These signaling molecules carry information from one cell to another and guide how cells respond. Some signaling molecules are gases, while others are proteins or peptides. Small lipids can also act as signals. In addition, cells may use steroids, amino acids, and even ions as signaling molecules. Each type of signaling molecule has different properties and works in a different way. Together, these molecules let cells send specific...

g protein-coupled receptors

G Protein-coupled Receptor Signaling

G protein-coupled receptors are a major class of cell-surface receptors. They help cells detect signals outside the cell and pass that information inward. These receptors are important in many kinds of cell communication. When a signal binds to a G protein-coupled receptor, the receptor changes shape. That change activates a G protein inside the cell. The activated G protein can then start a signaling pathway. This signaling system includes the receptor, the G protein, and the downstream...

cellular differentiation

From Stem Cell to Specialized Cells

Cellular differentiation turns unspecialized cells into specialized cells with specific jobs. This process helps a complex organism, such as a human, develop from a single fertilized egg into a body with many cell types. Nerve cells, muscle cells, and epithelial cells are examples of the final cell types that appear during development. A zygote is the first cell after fertilization. It is a totipotent stem cell, which means it has very high differentiation potential and can form all cell types...

key terms and concepts

Learn how mitosis separates copied chromosomes and how cytokinesis divides the cell into two daughter cells in this high school biology page.

Cell Division: Mitosis and Cytokinesis | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Cell Division: Mitosis and Cytokinesis

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