Name: cell cycle regulators that control division
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 27 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-4

molecular-factors-affecting-cell-division

Molecular Factors Affecting Cell Division

세포 분열 또는 세포주기의 유사분열 단계는 성장 인자 및 호르몬과 같은 외부 화학적 자극과 세포주기 조절자와 같은 내부 요인에 의해 제어됩니다.
세포주기는 cyclins와 cyclin-dependent kinase 또는 Cdks라고 하는 단백질의 조합에 의해 조절됩니다. 서로 다른 cyclins의 농도는 다른 세포주기 단계에 따라 변동합니다.
세포가 G2 단계의 끝에 가까워짐으로, cyclin B 수준은 상승합니다. 높은 농도에서, cyclin B는 M 상 승진 인자 또는 MPF에게 불린 Cdk1를 가진 복합물을 형성합니다.
MPF 활성은 세포가 분열하는지 여부를 결정하는 인산화 및 탈인산화 이벤트에 의해 조절됩니다.
G2가 끝날 때까지 Wee1 kinase는 MPF의 티로신 잔기를 인산화하고 비활성 상태로 유지합니다. 이는 세포주기 진입을 방지하고 G2/M기에서 세포를 정지시킵니다.
Cdc25가 MPF를 탈인산화하면 Cdk 활성화 키나아제는 MPF에서 보존된 트레오닌을 인산화하여 활성화합니다.
이제 세포는 유사분열을 거쳐 두 개의 딸 세포를 생산합니다.

세포 분열에 영향을 미치는 분자 요인

여러 외부 및 내부 요인이 세포 분열의 시작과 억제에 영향을 미칩니다. 예를 들어, 주변 세포가 죽거나 인간 성장 호르몬(hGH)이 방출되면 세포 분열이 촉진됩니다. 대조적으로, hGH가 부족하거나 세포가 밀집해 있으면 세포 분열이 억제될 수 있습니다.

여러 단백질은 각 세포 주기 단계가 다음 단계로 진행되기 전에 충실하게 완료되도록 보장하는 내부 조절자 역할을 합니다. 조절 분자는 직접적으로 작용하거나 다른 조절 단백질의 활성이나 생산에 영향을 미칠 수 있습니다. 이러한 조절 분자는 세포의 다음 단계로의 진행을 촉진하거나(양성 조절) 주기를 중단시킵니다(음성 조절).

양성 조절자 분자에는 세포 주기 진행에 필수적인 사이클린과 사이클린 의존성 키나제(Cdks)가 포함됩니다. Cdks 수준은 일정하게 유지되지만 4가지 사이클린(사이클린 D, E, A& B)의 수준은 세포 주기의 여러 단계에서 변동합니다. Cdk와 단단히 결합하면 사이클린이 인산화되어 활성화됩니다. 사이클린 D 수준은 G1 단계에서 증가하고 전체적으로 높은 수준을 유지하며 M 단계에서 감소합니다. Cyclin E 수준은 G1-S 단계의 교차점에서 최고조에 달하는 반면, Cyclin A는 S 및 G2 단계에서 높습니다. 세포가 M기에 가까워지면 사이클린 B 수준이 상승하고 세포 분열을 촉진합니다.

음성 조절 분자에는 세포 주기를 중단시키는 망막모세포종 단백질(Rb), p53 및 p21이 포함됩니다. 예를 들어, p53이 DNA 손상을 감지하면 DNA 복구 효소가 동원되어 손상을 교정합니다. DNA가 복구되지 않은 상태로 남아 있으면 p53은 세포 사멸 또는 세포 사멸을 시작하고 손상된 염색체 복제를 방지합니다. 세포 내 증가된 p53 수준은 또한 p21 합성을 유발할 수 있습니다. p21은 Cdk/cyclin 복합체에 결합하여 주기 진행을 중단합니다. p53과 p21의 축적은 세포가 DNA 합성(S기)으로 진행되는 것을 방해합니다. 이 문서는 <a href="https://openstax.org/books/biology-2e/pages/10-3-control-of-the-cell-cycle">Openstax, Anatomy and Physiology 2e, Section 10.3: Control of the Cell Cycle</a>에서 발췌되었습니다.

몇 가지 외부 및 내부 요인이 세포 분열의 시작과 억제에 영향을 미칩니다. 예를 들어, 주변 세포의 사멸 또는 방출 ...

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 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 push the cell forward, which is positive regulation, or stop the cycle, which is negative regulation.

The main positive regulators are cyclins and cyclin-dependent kinases, or Cdks. Cdks stay at a constant level, while cyclin levels rise and fall during the cell cycle. The four cyclins are cyclin D, cyclin E, cyclin A, and cyclin B. When cyclins bind tightly to Cdks, the complex becomes active after phosphorylation.

Each cyclin acts at a different point in the cycle. Cyclin D rises in G1, stays high through most of the cycle, and drops in M phase. Cyclin E peaks at the G1-S transition. Cyclin A is high during S and G2, and cyclin B rises as the cell nears M phase and helps drive cell division.

Negative regulators help prevent damaged or uncontrolled division. These include retinoblastoma protein, or Rb, p53, and p21. When p53 detects DNA damage, it recruits DNA repair enzymes. If the damage is not repaired, p53 can trigger apoptosis, or cell death, and prevent damaged chromosomes from being copied.

p53 can also increase p21 synthesis. The p21 protein binds to the Cdk/cyclin complex and blocks cycle progression. Together, p53 and p21 can stop the cell from entering DNA synthesis, which is the S phase.

Cell Cycle Regulators That Control Division

cell-cycle-regulators-that-control-division

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

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types of rna

RNA Types in Gene Expression

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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

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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: 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

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 external signals, cyclins, Cdks, p53, and p21 control cell division and help cells decide when to divide or stop.

Cell Cycle Regulators That Control Division | JoVE K12

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HS-LS1-2

Cell Cycle Regulators That Control Division

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