Name: centrosome duplication in cell division
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 2 min 25 s
Channel: JoVE
Description: Centrosome duplication is an important step in cell division. The centrosome helps organize the cell’s internal structure, and it must be copied before a cell divides.

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

Centrosome Duplication

الجسيم المركزي هو منظم الأنابيب الدقيقة الرئيسي لخلية حقيقية النواة ويلعب دورا حيويا في تكوين المغزل الانقسامي ، وهو ترتيب ثنائي القطب من الأنابيب الدقيقة التي تفصل بين الكروماتيدات الشقيقة. يتكون قطبا المغزل من اثنين من الجسيمات المركزية الموضوعة بشكل معاكس.
قبل دورة الخلية ، تحتوي معظم الخلايا الحيوانية على جسيم مركزي واحد فقط في السيتوبلازم. يساعد مركب كيناز أو Cdk المعتمد على G1 / S-cyclin - الذي يتكون من cyclin E و Cdk2 في الخلايا الحيوانية - على تحفيز ازدواجية الجسيم المركزي بالإضافة إلى دخول دورة الخلية. 
يتكون كل جسيم مركزي من اثنين من المريكزات ، والتي يتم تغليفها بواسطة مصفوفة بروتينية حول مركزية.
يبدأ ازدواجية الجسيم المركزي في مرحلة G1 المبكرة عندما يقوم الانفصال بفك الاشتباك بين المريكزين. البروتين الذي ينتمي إلى عائلة بروتين كيناز الشبيهة بالبولو ، Plk-4 ، هو منظم مهم للتكوين الحيوي للمنتز المركزية لدى البشر.
بالقرب من بداية المرحلة S ، يبدأ المريكز الابنة في النمو بزاوية قائمة على قاعدة كل مطرز.
خلال G2 ، عادة ما تنتهي المريكزات الابنة من الاستطالة. تظل المريكزات الأربعة قريبة من بعضها البعض في الجسيم المركزي حتى تدخل الخلية في الانقسام.
في بداية الانقسام ، ينقسم الجسيم المركزي إلى قسمين ، وهو ما يعرف أيضا باسم انفصال الجسيم المركزي. يحتوي كل من الجسيمين المركزيين الناتجين على زوج من المريكزات والمصفوفة المحيطة بالمفاصل. كلا الجسيمات المركزية نواة مجموعة من الأنابيب الدقيقة ، بشكل أساسي في المنترول الأم ، ويشكلان بشكل جماعي المغزل الانقسامي.
تتشابه دورة حياة الجسيم المركزي والكروموسوم في عدة جوانب. يحدث تكرارها مرة واحدة فقط في كل دورة وكلاهما يتكرر من خلال عملية شبه متحفظة حيث يتم إنتاج نسخة جديدة من النسخة الأصلية الموجودة مسبقا.
أيضا ، مثل الكروموسومات ، يتم توزيع نسخة واحدة من الجسيم المركزي بالتساوي على كل خلية ابنة بعد الانقسام.
يمكن أن يؤدي الازدواجية المفرطة للجسيم المركزي إلى إضعاف تجميع المغزل الانقسامي والتسبب في فصل الكروموسومات بشكل غير صحيح ، مما قد يسبب أمراضا مثل السرطان.

<ol>
	<li style="هامش يسار: 0.5 بوصة;">فوجيتا, هيروكي, يوكي يوشينو, وناتسوكو تشيبا. 2015. "تنظيم دورة الجسيم المركزي". علم الأورام الجزيئي والخلوي 3 (2). https://doi.org/10.1080/23723556.2015.1075643.</li>
	<li style="هامش يسار: 0.5 بوصة؛">Nigg, إريك أ., وأندرو ج. هولاند. 2018. "مرة واحدة ومرة واحدة فقط: آليات ازدواجية المريكز وإلغاء تنظيمها في المرض". مراجعات Nature بيولوجيا الخلية الجزيئية 19 (5): 297-312. https://doi.org/10.1038/nrm.2017.127.</li>
</ol>

ازدواجية الجسيم المركزي

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مركز تنظيم الأنابيب الدقيقة الأساسي (MTOC) في الخلايا الحيوانية هو الجسيم المركزي. يحتوي الجسيم المركزي على اثنين من المريكزات الأسطوانية في قلبه. يتكون كل مركز مركزي من تسع مجموعات من ثلاثة أنابيب دقيقة متماسكة بواسطة البروتينات. يتم وضع المريكزات بزوايا قائمة على بعضها البعض وتحيط بها سحابة بروتينية عديمة الشكل تسمى المصفوفة المحيطة بالمركز، أو المادة المحيطة بالمركز (PCMالتضمين النبضي المُرمز).

للتأكد من أن كل خلية وليدة تتلقى جسيمًا مركزيًا بعد انقسام الخلية، يبدأ تضاعف الجسيم المركزي في وقت مبكر من دورة الخلية. يتم تنظيم ازدواج الجسيم المركزي بإحكام عن طريق ضوابط دورة الخلية - مثل كيناز 2 المعتمد على السيكلين (Cdk2) - لمنع حدوثه أكثر من مرة في كل دورة خلية. وهكذا، بحلول الوقت الذي تصل فيه الخلية إلى الانقسام الفتيلي، يكون لديها اثنان من الجسيمات المركزية.

يتزامن ازدواج الجسيم المركزي مع مراحل دورة الخلية. خلال المرحلة G_1 من دورة الخلية، ينفصل المريكزان في الجسيم المركزي، وهي عملية تسمى الارتباك المركزي.

خلال المرحلتين G_1 وS، يتم تكرار الجسيمات المركزية. يبدأ مريكز جديد، يسمى المريكز المركزي، في التشكل والاستطالة عند قاعدة كل من المريكزين الموجودين. تستطيل المريكزات خلال S وG_2 حتى تصبح كبيرة مثل المريكزات الأقدم. تظل المريكزات الأربعة قريبة من بعضها البعض داخل PCM الموسع حتى تدخل الخلية في الانقسام.

خلال مرحلة G_2، يتراكم γ-tubulin وبروتينات PCM الأخرى في الجسيم المركزي، وهي عملية تسمى نضوج الجسيم المركزي.

أثناء الانتقال بين المرحلتين G_2 وM، تبدأ الجسيمات المركزية في الانفصال. ينفصل المريكزان الأم، وتقوم البروتينات المحركة للأنيبيبات الدقيقة بإبعاد الجسمين المركزيين عن بعضهما البعض.

يمكن أن تؤدي الأخطاء في تنظيم الجسيم المركزي إلى حدوث خلل في عدد الكروموسومات والجسيمات المركزية. تشوهات الجسيم المركزي والعيوب في تقدم دورة الجسيم المركزي متورطة في أمراض متعددة، ولا سيما السرطان. ترتبط البروتينات الكابتة للورم والجينات المسرطنة بالتغيرات الضارة في الجسيمات المركزية لخلايا الورم، مما يجعل هذه البروتينات هدفًا علاجيًا جذابًا.

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مركز تنظيم الأنابيب الدقيقة الأساسي (MTOC) في الخلايا الحيوانية هو الجسيم المركزي. يحتوي الجسيم المركزي على مركزين أسطوانيين في قلبه. كل...

Education

JoVE Core

Cell Biology

بيولوجيا الخلية

Unit 1

الوحدة الأولى

Cell Division

انقسام الخلية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

centrosome duplication in cell division

Centrosome duplication is an important step in cell division. The centrosome helps organize the cell’s internal structure, and it must be copied before a cell divides.

Centrosome Duplication in Cell Division

mitosis and cytokinesis

Stages of Cell Division in Eukaryotes

Cell division in eukaryotes follows a tightly regulated cycle that includes cell growth, DNA replication, chromosome duplication, chromosome distribution to daughter cells, and cell division. Regulatory systems and extracellular signals help control when cells divide. In typical human cells, the cycle takes about 24 hours. The cycle has two major stages. DNA is copied during the S phase of interphase. The mitotic, or M, phase then separates the duplicated chromosomes into two new nuclei and...

chromosome duplication

Chromosome Copying in Cell Division

Chromosome copying is an important step in cell division. Before a cell divides, it must make an exact copy of its chromosomes so each new cell can receive the same genetic information. A chromosome is a DNA-containing structure that carries genes. During duplication, the chromosome is copied into two identical sister chromatids. These copies stay attached until the cell is ready to separate them. This process helps ensure that daughter cells inherit a complete set of chromosomes. Accurate...

cohesins

Cohesins in Sister Chromatid Separation

Cohesins are protein complexes that help hold sister chromatids together after DNA is copied. They play a key role in cell division by keeping the two copies of a chromosome connected until the right time. These proteins act like a link between the sister chromatids. When the cell is ready to separate them, cohesins must be removed or released so each new cell can get one complete set of chromosomes. Cohesins are an important part of chromosome behavior during mitosis and meiosis. Their...

condensins

Condensin Proteins in Chromosome Packing

Condensin proteins help pack DNA into condensed chromosomes during cell division. They are part of the larger set of proteins that organize genetic material so it can be separated correctly when a cell divides. These proteins act by shaping and tightening chromosome structure. This process is important because DNA must be compacted before it can move through the stages of division. Condensins are therefore closely linked to chromosome condensation, the step that makes chromosomes more compact...

the mitotic spindle

How the Mitotic Spindle Guides Cell Division

The mitotic spindle guides chromosome movement during cell division. It is a structure made of microtubules, which are thin protein fibers in the cell. These fibers organize and help separate the genetic material before the cell splits. The spindle forms as the cell prepares to divide. Its fibers attach to chromosomes and line them up so they can be moved apart in an orderly way. This careful organization helps each new cell receive the correct set of chromosomes. The mitotic spindle is a key...

centrosome duplication

Centrosome duplication is an important step in cell division. The centrosome helps organize the cell’s internal structure, and it must be copied before a cell divides.

spindle assembly

Spindle Formation in Cell Division

Spindle formation in cell division is the process that builds the microtubule-based spindle needed to separate chromosomes. Microtubules are long protein fibers that help move and organize cell parts during division. During this process, microtubules grow and are arranged into a spindle structure around the chromosomes. The spindle forms in a way that supports chromosome movement to opposite sides of the cell. This step is essential for accurate cell division. Spindle formation depends on the...

attachment of sister chromatids

Sister Chromatid Attachment in Mitosis

Sister chromatid attachment in mitosis helps align duplicated chromosomes before they separate. Sister chromatids are the matching copies made after DNA replication. They stay connected until the cell is ready to divide. The attachment step is closely tied to the metaphase plate, the middle of the cell where chromosomes line up. This alignment helps each new cell receive one copy of every chromosome. Proper attachment is an important part of accurate cell division.

forces acting on chromosomes

Chromosome Movement During Cell Division

Chromosome movement during cell division depends on forces that act on the chromosomes. These forces help move the chromosomes into the right position as the cell divides. The transcript focuses on how these forces affect chromosome behavior during division. It highlights the role of the mitotic spindle, which is the structure that helps organize and move chromosomes. The spindle uses force to guide chromosome movement at the right time. Understanding these forces helps explain how...

separation of sister chromatids

Chromatid Pulling in Cell Division

Separation of sister chromatids is a key step in cell division. Sister chromatids are two identical copies of a chromosome that stay attached until the cell is ready to split them apart. Their separation helps each new cell receive the correct genetic material. During this stage, the sister chromatids are pulled to opposite sides of the cell. This movement happens as the cell prepares to divide into two daughter cells. Once the chromatids separate, each side of the cell has a complete set of...

the spindle assembly checkpoint

How Cells Verify Chromosome Spindle Attachment

The spindle assembly checkpoint helps cells verify that chromosomes are attached to the spindle before division continues. It acts as a safety step during cell division and helps prevent errors in chromosome separation. This checkpoint is controlled by kinetochores, which are protein structures on chromosomes that connect to spindle fibers. If a chromosome is not attached correctly, the checkpoint can delay progression until the problem is fixed. Once the attachment is correct, the cell can...

anaphase a and b

Chromosome and Spindle Movement in Anaphase

Anaphase is the stage of cell division when chromosomes move apart. In this phase, sister chromatids separate and travel toward opposite poles of the cell. Chromosome movement in anaphase can happen in two ways. In anaphase A, chromosomes move closer to the poles as the microtubules attached to them shorten. In anaphase B, the spindle poles themselves move farther apart and help stretch the cell. These two movements work together to ensure that the separated chromosomes are pulled to opposite...

anaphase promoting complex

Cell Cycle Control by APC

The anaphase-promoting complex, or APC, helps control cell cycle progression. It acts during cell division to help move the process from one stage to the next. This control is important for proper timing in the cell cycle. APC is a protein complex that works as a regulator. It helps trigger key steps that allow division to continue in an ordered way. By guiding this transition, APC supports normal cell cycle control.

the contractile ring

Cell Division and the Contractile Ring

The contractile ring helps cells divide at the end of cell division. It forms at the cell's center and tightens to split one cell into two. This process is part of cytokinesis, the stage when the cytoplasm divides. The ring is made of actin and myosin, two proteins that can work together to create force. As the ring contracts, it draws the cell membrane inward. This pinch helps separate the two daughter cells. Understanding the contractile ring is important for studying how cells complete...

determining the plane of cell division

Spindle Position and Cell Division Plane

The plane of cell division is set by the position of the spindle during mitosis. Cells use this internal structure to help decide where the cell will split. The result affects how the two daughter cells are arranged after division. This process is important in many developing tissues. It helps explain how cells divide in a controlled direction. A clear plane of division supports proper cell organization as new cells form. The transcript focuses on how the spindle is used to determine that...

the phragmoplast

Phragmoplast in Plant Cell Division

The phragmoplast is a plant cell structure that forms during cell division. It helps guide the final stage of division, when the cell begins to split into two daughter cells. In plant cells, the phragmoplast appears between the two new nuclei. It is part of the process that leads to the formation of a new cell wall. This wall separates the daughter cells after division is complete. The phragmoplast plays an important role in plant cytokinesis, which is the physical division of the cytoplasm.

distribution of cytoplasmic content

Cytoplasmic Content During Cell Division

Cytoplasmic content is distributed as a cell divides. This process helps each new cell receive the materials it needs to function. The cytoplasm includes the fluid and structures inside the cell membrane, but outside the nucleus. During cell division, this content is separated between the two daughter cells. The division must be organized so both cells can continue normal activity after the split. The video focuses on how this distribution occurs as part of cell division. It highlights the...

key terms and concepts

Learn how centrosome duplication supports cell division and helps a cell prepare for the next stage of growth and division in grades 9–12 biology.

Centrosome Duplication in Cell Division | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Louisiana Student Standards for Science

High School

Life Sciences

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

From Molecules To Organisms: Structures And Processes

HS-LS1-4

Tennessee Academic Standards

Biology

From Molecules to Organisms: Structures and Processes

BIO1.LS1.6

Minnesota Academic Standards in Science

3.1.1 9L.3.1.1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Arizona Science Standards

HS+B.L1

HS+B.L1U1.9

Alabama Course of Study Science

9-12.B.1.3

Next Generation Science Standards

Florida Department of Education

SC.912.L.16

SC.912.L.16.14

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS1-4.

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS1-4.

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 ...

The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

Mitosis and Cytokinesis

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

Chromosome Duplication

Cohesins

Condensins

The Mitotic Spindle

Spindle Assembly

Attachment of Sister Chromatids

Forces Acting on Chromosomes

Separation of Sister Chromatids

The Spindle Assembly Checkpoint

Anaphase A and B

Anaphase Promoting Complex

The Contractile Ring

Determining the Plane of Cell Division

The Phragmoplast

Distribution of Cytoplasmic Content

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Cell Migration

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an-introduction-to-developmental-genetics

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Fate Mapping

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Students who demonstrate understanding can use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms.  Assessment Boundary: Assessment does not include specific gene control mechanisms or rote memorization of the steps of mitosis.

DNA Packaging

DNA as a Genetic Template

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Organization of Genes

Structure of a Gene

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Chromosome Structure

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The centromere is a DNA ...

Chromosome Replication

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The Nucleosome

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Nucleosome Remodeling

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Chromatin Packaging

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Karyotyping

Proteins: From Genes to Degradation

The DNA Helix

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The Central Dogma

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Mutations

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genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

Gene Families

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3.1.9-12.P

Genomic DNA in Prokaryotes

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Binary Fission

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Genomic DNA in Eukaryotes

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What is Meiosis?

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Meiosis I

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Meiosis II

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Students who demonstrate understanding can make and defend a claim based on evidence that inheritable genetic variations may result from (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors. Assessment Boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.

3.1.9-12.Q

Centrosome Duplication in Cell Division

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