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

유사분열은 세포의 유전 물질이 두 개의 딸 세포 사이에서 분할되는 세포 분열의 한 형태입니다. 
첫째, 전구기(prophase) 동안 핵 염색질은 중심체 접합부에 부착된 자매 염색체 쌍으로 구성된 x자형 염색체로 응축됩니다.
동시에 중심체는 반대쪽 세포면으로 이동합니다. 그렇게 하면서 미세소관 막대가 각각에서 자라기 시작하여 거미줄과 같은 방추 장치를 형성합니다.
다음으로, 핵막은 전중기(prometaphase) 동안 용해되고 키네토코어(kinetochores)라고 하는 단백질 구조가 모든 염색질에 대해 하나씩 중심체의 양쪽에 나타납니다.
이러한 키네토코어가 형성되면 확장된 내부 미세소관이 여기에 고정되고 각 자매 염색체는 다른 세포극에 묶입니다.
중기(metaphase)에서, 방추체(spindle apparatus)는 염색체가 세포의 적도를 따라 고정된 열로 향하도록 염색체를 재배열합니다.
anaphase를 사용하면 kinetochore가 고정된 미세소관이 짧아지고 자매 염색체가 분리됩니다. 이러한 미세소관 역학 및 기타 미세소관 역학도 세포를 연장합니다.
텔로 페이즈 동안, 스핀들 장치는 해체되고, 염색체가 느슨해지고, 핵막이 재형성됩니다.
마지막으로, 세포는 사이토키네시스(cytokinesis)에 의해 세포질로 분열되어 전구체와 유전적으로 동일한 한 쌍의 세포를 형성합니다.

<ol>
	<li>Guertin, David A., Susanne Trautmann, and Dannel McCollum. "진핵생물의 사이토키네시스." Microbiol. Mol. Biol. Rev. 66, no. 2 (June 1, 2002): 155–78.</li>
</ol>

유사분열(mitosis)과 사이토키네시스(cytokinesis)

Mitosis And Cytokinesis

진핵생물에서 세포분열주기는 세포 성장, DNA 복제/염색체 복제, 딸 세포로의 염색체 분포, 마지막으로 세포 분열을 포함하는 뚜렷하고 조화로운 세포 과정으로 나뉩니다. 세포주기는 조절 시스템과 세포 증식에 영향을 미치는 세포외 신호에 의해 엄격하게 조절됩니다.

세포주기의 과정은 대략 24시간에 걸쳐(일반적인 인간 세포에서) 발생하며 두 가지 주요 단계로 구분됩니다. 첫 번째 단계는 간기의 S 단계 동안 DNA 복제입니다. 두 번째 단계는 복제된 염색체가 두 개의 새로운 핵으로 분리(유사분열)되고 세포질 분열(세포질 분열)이 이루어지는 유사분열(M) 단계입니다. 두 단계는 간격(G1 및 G2 간격)으로 구분되며, 이 기간 동안 세포는 복제와 분열을 준비합니다.

유사분열 과정

유사분열은 전기, 전중기, 중기, 후기, 말기의 5가지 단계로 나눌 수 있습니다. 후기 또는 말기(세포에 따라 다름) 동안 시작되는 세포질 분열은 M기의 일부이지만 유사분열의 일부는 아닙니다.

전기

세포가 유사분열에 들어가면서 복제된 염색체가 응축되기 시작하고 콘덴신으로 알려진 단백질의 도움으로 실 같은 구조로 보이게 됩니다. 유사분열 방추 장치는 S기 동안 복제된 중심체 사이에서 형성되기 시작하고 세포의 반대편 극으로 이동합니다. 방추는 튜불린 단백질 단량체로 구성된 미세소관이라는 필라멘트 구조로 구성됩니다. 방추 미세소관은 응축된 염색체 쪽으로 확장되기 시작합니다. 리보솜을 생성하는 핵의 구성 요소인 핵소체는 사라지며 이는 핵의 붕괴가 임박했음을 나타냅니다.

전중기

전중기 동안 방추사 장치의 미세소관 필라멘트가 계속해서 성장하고 염색체의 응축이 완료됩니다. 핵 봉투가 완전히 분해되어 염색체가 방출됩니다. 미세소관 중 일부는 방출된 염색체에 부착되어 각 자매 염색체 쌍의 동원체에 존재하는 동원체라고 불리는 단백질 구조에 결합합니다. 반대편 극의 방추 미세소관은 동원체에 부착되어 응축된 자매 염색분체 쌍을 포착합니다. 염색체에 부착되지 않은 방추 미세소관(극성 및 성상 미세소관)은 방추를 밀어내고 방추 극을 세포막에 고정시키는 데 도움이 됩니다.

중기

방추 미세소관은 중기판에서 세포의 적도를 따라 완전히 응축된 자매 염색 분체의 각 쌍을 정렬합니다. 이제 세포를 나눌 준비가 되었습니다.

후기

동원체 구조에 부착된 반대편 방추 극의 미세소관은 동원체에서 자매 염색분체를 짧게 하고 분리합니다. 이제 염색 분체를 함께 묶는 응집 단백질이 분해됩니다. 단축된 동원체 미세소관은 쌍의 각 염색분체(현재 염색체라고 함)가 반대극으로 이동하도록 합니다.

말기

염색체가 세포의 반대극에 도달하면 응축이 풀려 염색질을 형성합니다. 스핀들 미세소관 필라멘트는 튜불린 단량체로 해중합되어 딸세포에서 세포골격 요소로 활용됩니다. 핵 봉투는 각 염색체 세트 주위에 재조립됩니다.

세포질 분열

동물 세포에서 세포질 분열이 진행되는 동안 액틴 필라멘트는 원형질막에 수축성 고리를 형성하여 분열 고랑을 생성하고 결국 세포를 두 개로 꼬집습니다. 식물 세포에서는 포도당, 효소, 구조 단백질을 운반하는 골지체 소포가 결합하여 이전 중기판 위치에 새로운 세포판을 형성합니다. 성장하는 세포판은 양쪽의 원형질막과 융합되어 결국 세포를 둘로 나누는 새로운 세포벽을 형성합니다.

이제 유사분열이 완료되어 모세포와 동일한 두 개의 딸세포가 생성됩니다. 대부분의 인간 세포에서 유사분열은 대략 24시간의 세포 주기 중 약 1시간을 차지합니다.

유사분열(Mitosis)과 사이토키네시스(Cytokinesis)

진핵생물에서 세포 분열 주기는 세포 성장, DNA 복제/염색체를 포함하는 뚜렷하고 조정된 세포 과정으로 나뉩니다.

Education

교육

JoVE Core

Anatomy and Physiology

해부학 및 생리학

Unit 1

제1단원

Essential Cellular Processes

필수 세포 과정

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

Description

Transcript

Tags