Name: cell cycle checkpoints and cancer
Uploaded: 2025-08-06T09:37:54.000Z
Duration: 1 min 4 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

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

From Molecules to Organisms- Structures and Processes

LS.Bio.2.1

What is the Cell Cycle?

تشير دورة الخلية إلى تسلسل الأحداث طوال فترة عمر الخلية المعتاد،بما في ذلك النمو،نسخ الحمض النووي وأحيانًا المزيد من النمو والانقسام. وللكائنات الحية التي تتكاثر جنسيًا،تبدأ الحياة كلاقحة،بويضة مخصبة. وبمرور الوقت،تنمو الخلية المفردة الأصلية وتنقسم بطريقة منضبطة لإنتاج فرد مُرَكَب متعدد الخلايا.وتستمر الخلية في هذه العملية،خصوصًا للحفاظ على الأنسجة وإصلاحها خلال التقدم في العمر. وعلى النقيض،فإن الكائنات الحية وحيدة الخلية مثل البكتيريا تعتمد على الانقسام الخلوي ببساطة لكي تتكاثر عبر الانشطار الثنائي. ولسوء الحظ،إذا لم يُكبَح جماح الانقسام الخلوي،ينتج السرطان،مع فقدان السيطرة على المتواليات الجينية التي تنظم العملية الطبيعية.

شير ، تشارلز ج. ، وجيري بارتيك. "دورة الخلية - علاجات السرطان المستهدفة". المراجعة السنوية لبيولوجيا السرطان 1 ، العدد 1 (2017): 41-57. [<a href = "https://doi.org/10.1146/annurev-cancerbio-040716-075628" target = "__blank" >مصدر</a>]

ما هي دورة الخلية؟

تشير دورة الخلية إلى تسلسل الأحداث التي تحدث طوال حياة الخلية النموذجية. في الخلايا حقيقية النواة ، تتكون دورة الخلية الجسدية من مرحلتين: الطور البيني والمرحلة الانقسامية. أثناء الطور البيني ، تنمو الخلية وتؤدي وظائفها الأيضية الأساسية وتنسخ الحمض النووي الخاص بها وتستعد لانقسام الخلايا الانقسامية. ثم ، أثناء الانقسام الخلوي والانقسام السيتوبلازمي ، تقسم الخلية موادها النووية والسيتوبلازمية ، على التوالي. يؤدي هذا إلى إنشاء خليتين ابنتين متطابقتين مع الخلية الأم الأصلية. تعد دورة الخلية ضرورية لنمو الكائن الحي ، واستبدال الخلايا التالفة ، وتجديد الخلايا المسنة. السرطان هو نتيجة الانقسام الخلوي غير المنضبط الذي تسببه طفرة جينية.

<h4>نقاط فحص دورة الخلية</h4>

هناك ثلاث نقاط تفتيش رئيسية في دورة الخلية حقيقية النواة. عند كل نقطة تفتيش ، يمكن إيقاف التقدم إلى مرحلة دورة الخلية التالية حتى تصبح الظروف أكثر ملاءمة. نقطة تفتيش G1 هي أول هذه النقاط ، حيث يتم تقييم حجم الخلية ، والطاقة ، والمغذيات ، وجودة الحمض النووي ، والعوامل الخارجية الأخرى. إذا اعتبرت الخلية غير كافية ، فإنها لا تستمر في المرحلة S من الطور البيني. نقطة تفتيش G2 هي نقطة التفتيش الثانية. هنا ، تضمن الخلية أن كل الحمض النووي قد تم نسخه ولا يتلف قبل الدخول في الانقسام الخلوي. إذا تم الكشف عن أي تلف في الحمض النووي لا يمكن إصلاحه ، فقد تخضع الخلية لموت الخلايا المبرمج ، أو موت الخلية المبرمج. تضمن نقطة التفتيش M ، أو المغزل ، أن جميع الكروماتيدات الشقيقة متصلة بشكل صحيح بالأنابيب الدقيقة للمغزل في صفيحة الطور قبل أن تدخل الخلية الطور الانفصالي.

<h4>السرطان: عندما تنحرف دورة الخلية</h4>

تضمن نقاط فحص دورة الخلية أن الخلايا السليمة تتحرك خلال دورة الخلية بطريقة منظمة. ومع ذلك ، غالباً ما تتجاوز الخلايا السرطانية نقاط التفتيش هذه. كل جولة متتالية من الانقسام الخلوي غير المضبوط تنتج المزيد من الخلايا الوليدة التالفة. بالإضافة إلى ذلك ، يمكن أن تنقسم الخلايا السرطانية في جسم الإنسان عدة مرات أكثر من الخلايا الطبيعية ، والتي لا يمكن أن تخضع إلا لحوالي ٤٠_٦٠ جولة من الانقسام. تنتج الخلايا السرطانية إنزيم تيلوميريز ، وهو إنزيم يقوم بإصلاح التآكل والتمزق في نهايات الكروموسومات والذي يحدث عادة بسبب انقسام الخلايا.

تشير دورة الخلية إلى تسلسل الأحداث التي تحدث طوال حياة الخلية النموذجية. في الخلايا حقيقية النواة ، تحتوي دورة الخلية الجسدية على نوعين ...

Education

JoVE Core

علم الأحياء

Cellular Processes

العمليات الخلوية

Cell Cycle and Division

دورة الخلية وانقسامها

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

cell cycle checkpoints and cancer

The cell cycle is the set of steps a eukaryotic cell follows as it grows and divides. In somatic cells, it has two main stages: interphase and the mitotic phase. During interphase, the cell grows, carries out its basic metabolic functions, copies its DNA, and gets ready for mitotic cell division.

After interphase, the cell enters mitosis and cytokinesis. Mitosis divides the nuclear material, and cytokinesis divides the cytoplasm. These steps produce two daughter cells that are identical to the original parent cell.

The cell cycle is important for many body processes. It supports growth, replaces damaged cells, and helps regenerate older cells. When the cycle is disrupted by a gene mutation, uncontrolled cell division can lead to cancer.

Eukaryotic cells also use checkpoints to control cell cycle progress. The G1 checkpoint checks cell size, energy, nutrients, DNA quality, and other external factors before the cell enters S phase. The G2 checkpoint confirms that DNA has been fully copied and is not damaged before mitosis begins. If damage cannot be repaired, the cell may undergo apoptosis, or programmed cell death.

The M checkpoint, also called the spindle checkpoint, acts during mitosis. It makes sure the sister chromatids are properly attached to spindle microtubules at the metaphase plate before anaphase starts. These checkpoints help healthy cells divide in a regulated way, but cancer cells often bypass them. As a result, each round of unchecked division can create more damaged daughter cells, and cancer cells may divide far more times than normal cells, which usually complete about 40 to 60 divisions. Cancer cells also express telomerase, an enzyme that helps repair chromosome ends worn down by repeated cell division.

Cell Cycle Checkpoints and Cancer

what is the cell cycle?

The cell cycle is the set of steps a eukaryotic cell follows as it grows and divides. In somatic cells, it has two main stages: interphase and the mitotic phase. During interphase, the cell grows, carries out its basic metabolic functions, copies its DNA, and gets ready for mitotic cell division. After interphase, the cell enters mitosis and cytokinesis. Mitosis divides the nuclear material, and cytokinesis divides the cytoplasm. These steps produce two daughter cells that are identical to the...

genomic dna in prokaryotes

Prokaryote Chromosomes and Plasmids

Most prokaryotes store their DNA in one circular chromosome inside the nucleoid, a region of cytoplasm. This chromosome is double-stranded and tightly wound, or supercoiled, so it fits efficiently inside the cell. Prokaryotes also carry smaller circular DNA pieces called plasmids. Plasmids often carry genes that give bacteria helpful traits. One important example is antibiotic resistance. Bacteria can gain these plasmids and the traits they carry, which can help them adapt to changing...

binary fission

How Cells Split by Binary Fission

Binary fission is a common way that bacteria and archaea reproduce. In this process, one parent cell divides into two parts. Each new cell can then grow to the size of the original parent cell. This is an asexual form of reproduction, so the cells produced are genetically identical. Binary fission can happen very fast. In the time it takes one bacterial cell to divide, the number of cells in the culture doubles. That time is called the doubling time. Escherichia coli cells often divide every...

genomic dna in eukaryotes

How Eukaryotic DNA Fits Inside the Nucleus

Eukaryotic DNA fits inside the nucleus by packing into a highly compact form. Eukaryotes have large genomes compared with prokaryotes, so their DNA must be tightly organized to fit inside one cell. The process starts when DNA wraps around proteins called histones. These DNA-histone units form nucleosomes, which are connected by linker DNA. The nucleosomes then coil into chromatin fibers, and additional fibrous proteins compact the chromatin even more. This packed material is called chromatin,...

interphase

Interphase in the Cell Growth Cycle

Interphase is the stage of the cell cycle when a eukaryotic cell grows and copies its DNA before mitosis. In a typical human cell, the full cell cycle takes about 24 hours, and interphase makes up about 95 percent of that time. It is followed by mitosis, also called M, when the cell divides. After mitosis and cytokinesis, cells enter the G1 phase, or gap 1. During G1, cells grow continuously and prepare for DNA replication. They are metabolically active and copy essential organelles and...

mitosis and cytokinesis

Cell Cycle Stages in Mitosis

Cell cycle stages in mitosis show how a eukaryotic cell copies its DNA and then divides into two daughter cells. The cycle is controlled by regulatory systems and by outside signals that affect cell growth and division. In typical human cells, the full cycle takes about 24 hours and includes two major phases. The first is DNA replication during the S phase of interphase. The second is the mitotic, or M, phase, which includes mitosis and cytokinesis. G1 and G2 are the gap stages between these...

positive regulator molecules

Cyclins and CDKs in the Cell Cycle

Cyclins and CDKs help control the cell cycle, the process that produces daughter cells. Cells use internal checkpoints to make sure their size, energy reserves, and DNA are ready before they move forward. At these checkpoints, positive regulators help the cell continue, while negative regulators slow or stop it. The main positive regulators are cyclins and cyclin-dependent kinases, or CDKs. These proteins are found in eukaryotes, from yeast to humans. Cyclins are grouped by the stage they help...

negative regulator molecules

Cell Cycle Stop Signals: p53, p21, and Rb

Cell cycle stop signals help control when a cell can move forward through division. Negative regulators pause or end the cell cycle until the cell meets the right conditions. Three well-studied negative regulators are p53, p21, and retinoblastoma protein, or Rb. Their roles became clear after faulty versions were found in cancer cells that kept replicating uncontrollably. These proteins act mostly at the G1 checkpoint, which comes early in the cell cycle. P53 has a strong effect on whether a...

cancer

Cancer Treatment, Personalization, and Cell Growth

Cancer develops when mutations affect genes that control cell division. Those changes can remove the normal brakes on growth and lead to uncontrolled cell proliferation. Modern science and medicine have improved how cancer is understood and treated, and some patients can now be cured. There is still no single cure for cancer because cancer is not one disease. It is a large group of many diseases. Even when two people have the same mutation in an oncogene or a tumor suppressor gene, their...

key terms and concepts

Learn how the cell cycle is controlled by G1, G2, and M checkpoints, and how checkpoint failure and telomerase activity can contribute to cancer.

Cell Cycle Checkpoints and Cancer | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

Pennsylvania State Academic Standards

Life Science

Inheritance and Variation of Traits

3.1.9-12.Q

Virginia  Standards of Learning

HIgh School

BIO.3

BIO.3.c

LS.2

LS.2.d

Next Generation Science Standards

High School

From Molecules to Organisms: Structures and Processes

HS-LS1-4

Texas Essential Knowledge and Skills

BIO.6

BIO.6.A

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS1-4.

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Analyze how the relationship between structure and function supports life processes within organisms.

Cell Cycle Checkpoints and Cancer

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