Name: cell cycle checkpoints and cyclin control
Uploaded: 2025-05-22T09:05:54.000Z
Duration: 1 min 28 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Biology

BIO.6

BIO.6.A

The Cell Cycle Control System

System kontroli cyklu komórkowego zawiera białka regulatorowe, które zatrzymują cykl komórkowy w fazach G1 , G2 i mitotycznych.
Pomagają one zapobiec rozpoczęciu kolejnego etapu, dopóki wcześniejsze etapy nie zostaną zakończone bez żadnych błędów.
Ponadto te kluczowe białka regulatorowe, zwane kinazami białkowymi zależnymi od cyklin lub Cdk, tworzą kompleksy z cyklinami i zapewniają, że wszystkie etapy są skoordynowane i prawidłowo zaplanowane.
W punkcie kontrolnym G1 białko regulatorowe sprawdza, czy komórka osiągnęła rozmiar krytyczny, czy DNA jest wolne od błędów i czy obecna jest wystarczająca ilość składników odżywczych i czynników wzrostu, aby wejść w fazę S w celu syntezy DNA.
Jeśli ogniwo nie otrzyma niezbędnego sygnału, przełącza się w stan spoczynku lub fazę G0.
W przeciwnym razie DNA ulega replikacji, a komórka napotyka punkt kontrolny G2, w którym białka regulatorowe sprawdzają błędy w DNA przed wejściem w mitozę.
Podczas mitozy, po tym, jak białko regulatorowe sprawdzi, czy chromosomy są przyłączone do wrzeciona i są dokładnie wyrównane, komórka przechodzi do podziału.
W dowolnym momencie cyklu komórkowego, jeśli białko regulatorowe wykryje nieodwracalne uszkodzenie, następuje śmierć komórki.

system kontroli cyklu komórkowego

System regulacji cyklu komórkowego kieruje sposobem, w jaki komórka przechodzi z jednej fazy do drugiej i rozpoczyna mitozę. System kontroli cyklu komórkowego obejmuje wewnętrzne cząsteczki regulujące oraz zewnętrzne bodźce. Dostarczają one sygnały "stop" lub "do przodu" i działają w określonych etapach cyklu komórkowego określanych jako punkty kontrolne, aby zapewnić, że określony proces zostanie ukończony, zanim komórka przejdzie do następnej fazy.

Cikliny i kinazy zależne od ciklin (Cdki) są głównymi regulatorami cyklu komórkowego i działają na fazach G1, G2 i M cyklu komórkowego. Regulatorzy na punkcie kontrolnym G1 weryfikują, czy są dostępne odpowiednie warunki do syntezy DNA, takie jak rozmiar komórki i czynniki wzrostu. Jeśli komórka nie spełnia tych wymagań, jest powstrzymywana przed wejściem w fazę S. Komórka albo zatrzymuje cykl komórkowy, albo przechodzi do fazy G0, aż spełni swoje wymagania. Regulatorzy na punkcie kontrolnym G2 weryfikują, czy zreplikowane DNA jest wolne od uszkodzeń lub błędów; w przeciwnym razie mechanizm naprawy DNA naprawia uszkodzenia, a następnie pozwala komórce przejść do kolejnego etapu. Regulatorzy na punkcie kontrolnym fazy M zapewniają, że siostrzane chromatydy są prawidłowo ustawione i przyłączone do mikrotubul w płaszczyźnie równikowej metafazy. Pozwala to komórce przejść do fazy anafazy podziału komórki i wytworzyć dwie komórki potomne o równoległej liczbie chromosomów.

Jeśli komórka nie przechodzi przez którykolwiek z powyższych punktów kontrolnych i kontynuuje postępowanie przez mitozę, gromadzi mutacje, które mogą ostatecznie prowadzić do niekontrolowanego wzrostu lub powstania guza.

Ten tekst jest adaptacją z <a href="https://openstax.org/books/anatomy-and-physiology/pages/3-5-cell-growth-and-division">Openstax, Anatomy and Physiology 2e, Section 3.5: Section Title Cell Growth and Division</a>

System kontroli cyklu komórkowego

Regulacja cyklu komórkowego kieruje tym, jak komórka przechodzi z jednej fazy do drugiej i rozpoczyna mitozę. System kontroli cyklu komórkowego obejmuje wewnątrzkomórkowe ...

Education

JoVE Core

Anatomy and Physiology

Anatomia i fizjologia

Unit 1

Jednostka 1

Essential Cellular Processes

Podstawowe procesy komórkowe

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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 orderly.

The G1 checkpoint checks whether the cell is ready for DNA synthesis. It looks at conditions such as cell size and growth factors. If these needs are not met, the cell does not enter S phase. Instead, it may pause the cycle or move into G0 until the conditions improve.

The G2 checkpoint reviews the replicated DNA before the cell moves on. It checks for damage or copying errors. If problems are found, DNA repair mechanisms fix the damage before the cell continues.

The M phase checkpoint acts during metaphase. It checks that sister chromatids are correctly aligned and attached to microtubules at the equatorial plane. When this happens, the cell can move into anaphase and form two daughter cells with the same number of chromosomes.

If a cell passes through these checkpoints without correction, mutations can build up. Over time, this may lead to uncontrolled growth or tumor formation. For that reason, cell cycle checkpoints are important for keeping division accurate.

Cell Cycle Checkpoints and Cyclin Control

cell-cycle-checkpoints-and-cyclin-control

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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interphase

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the cell cycle control system

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

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what is meiosis?

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overview of cell signaling

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cellular differentiation

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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

Explore how cyclins, Cdks, and checkpoints regulate the cell cycle at G1, G2, and M phases to protect DNA and guide normal cell division.

Cell Cycle Checkpoints and Cyclin Control | 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.

What is the Cell Cycle?

The cell cycle refers to the sequence of events occurring throughout a typical cell&#8217;s life. In eukaryotic cells, the somatic cell cycle has two ...

Interphase

The cell cycle occurs over approximately 24 hours (in a typical human cell) and in two distinct stages: interphase, which includes three phases of the ...

Mitosis and Cytokinesis

In eukaryotes, the cell division cycle is divided into distinct, coordinated cellular processes that include cell growth, DNA replication/chromosome ...

Positive Regulator Molecules

To consistently produce healthy cells, the cell cycle&mdash;the process that generates daughter cells&mdash;must be precisely regulated.

Internal ...

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a ...

Cancer

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Replication in Prokaryotes

Overview

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Replication in Eukaryotes

Overview

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high ...

Proofreading

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Mitogens and the Cell Cycle

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Explain the importance of the cell cycle to the growth of organisms, including an overview of the stages of the cell cycle and deoxyribonucleic acid (DNA) replication models.

Cellular Differentiation

How does a complex organism such as a human develop from a single cell? It all starts from a single fertilized egg which gives rise to a vast array of ...

Cell Diversity

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An Introduction to Stem Cell Biology

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Explain the process of cell specialization through cell differentiation, including the role of environmental factors.

BIO.6.B

Abnormal Proliferation

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Relate disruptions of the cell cycle to how they lead to the development of diseases such as cancer.

BIO.6.C

Science concepts--biological structures, functions, and processes. The student knows how an organism grows and the importance of cell differentiation. The student is expected to:

Cell Cycle Checkpoints and Cyclin Control

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