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

Die Zellteilung oder die mitotische Phase des Zellzyklus wird durch äußere chemische Reize wie Wachstumsfaktoren und Hormone sowie interne Faktoren wie Zellzyklusregulatoren gesteuert.
Der Zellzyklus wird durch eine Kombination von Proteinen reguliert, die Cycline und Cyclin-abhängige Kinasen oder Cdks genannt werden. Die Konzentrationen verschiedener Cycline schwanken mit den verschiedenen Zellzyklusphasen.
Wenn sich eine Zelle dem Ende der G2-Phase nähert, steigt der Cyclin-B-Spiegel an. Bei hohen Konzentrationen bildet Cyclin B mit Cdk1 einen Komplex, der als M-Phasen-Förderfaktor oder MPF bezeichnet wird.
Die MPF-Aktivität wird durch Phosphorylierungs- und Dephosphorylierungsereignisse reguliert, die bestimmen, ob die Zelle eine Teilung durchläuft oder nicht.
Bis zum Ende von G2 phosphoryliert die Wee1-Kinase Tyrosinreste auf MPF und hält es inaktiv. Dies verhindert den Eintritt in den Zellzyklus und stoppt die Zelle in der G2/M-Phase.
Sobald Cdc25 MPF dephosphoryliert, phosphoryliert eine Cdk-aktivierende Kinase ein konserviertes Threonin auf MPF und aktiviert es.
Nun durchlaufen die Zellen die Mitose und produzieren zwei Tochterzellen.

molekulare faktoren, die die zellteilung beeinflussen

Mehrere externe und interne Faktoren beeinflussen die Initiation und Hemmung der Zellteilung. Externe Faktoren wie der Tod benachbarter Zellen, die Freisetzung von menschlichem Wachstumshormon (hGH) oder Wachstumsfaktoren, die an spezifische Rezeptoren auf der Zelloberfläche binden, fördern die Zellteilung. Im Gegensatz dazu können ein Mangel an hGH, eine Zellüberfüllung oder unzureichende Zell-Matrix-Interaktionen die Zellteilung hemmen. Mehrere Proteine fungieren als interne Regulatoren und stellen sicher, dass jede Phase des Zellzyklus ordnungsgemäß abgeschlossen wird, bevor die nächste beginnt. Diese regulatorischen Moleküle fördern entweder den Fortschritt der Zelle zur nächsten Phase (positive Regulation) oder stoppen den Zyklus (negative Regulation). Positive regulatorische Moleküle umfassen Cycline und cyclinabhängige Kinasen (Cdks). Während der Cdk-Spiegel konstant bleibt, schwanken die Spiegel von Cyclinen (Cyclin D, E, A & B) während des Zellzyklus. Nach ihrer Bindung an Cdks werden Cycline zur Aktivierung phosphoryliert, wobei jeder Cyclin-Typ spezifische Phasen des Zellzyklus beeinflusst. Negative regulatorische Moleküle wie das Retinoblastomprotein (Rb), p53 und p21 fungieren als Tumorsuppressoren und stoppen den Zellzyklus. p53 initiiert bei DNA-Schäden die Reparatur oder Apoptose, um die Duplikation geschädigter Chromosomen zu verhindern. Eine erhöhte p53-Menge führt zur Synthese von p21, das den Cdk/Cyclin-Komplex bindet und den Zyklusfortschritt stoppt. Zellzyklus-Checkpoints überprüfen die Integrität der DNA und den Vollständigkeitsgrad der vorherigen Phase, bevor die Zelle in die nächste Phase übergeht. Dieser Text wurde teilweise angepasst von <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>

Molekulare Faktoren, die die Zellteilung beeinflussen

Mehrere äußere und innere Faktoren beeinflussen die Initiierung und Hemmung der Zellteilung. Zum Beispiel der Tod benachbarter Zellen oder die Freisetzung von ...

Education

Lehre

JoVE Core

Anatomy and Physiology

Anatomie und Physiologie

Unit 1

Einheit 1

Essential Cellular Processes

Essentielle Zellprozesse

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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

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translation

Translation: mRNA to Protein

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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

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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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Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. [Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.] [Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.]

HS-LS1-2

Cell Cycle Regulators That Control Division

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