Name: chromosome and spindle movement in anaphase
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 1 min 39 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

Anaphase A and B

La ségrégation chromosomique a lieu pendant l’anaphase : lorsque les chromatides sœurs se séparent et que les chromatides individuelles se déplacent vers les pôles opposés de la cellule.
La progression de l’anaphase constitue deux processus indépendants mais qui se chevauchent : l’anaphase A et l’anaphase B.
Au cours de l’anaphase A, en l’absence de cohésion des chromatides sœurs, deux forces polaires agissent sur les chromosomes.
La dépolymérisation des microtubules au niveau du kinétochore produit une force vers le pôle. Le flux de microtubules, issu de la dépolymérisation de l’extrémité négative, génère également une force vers le pôle. La combinaison de ces deux forces vers les pôles, accompagnée d’un raccourcissement des microtubules kinétochores, tire les chromatides individuelles vers les pôles du fuseau.
Lorsque les chromosomes filles se déplacent vers les pôles, l’anaphase B commence et les pôles du fuseau sont séparés, allongeant le fuseau. Les protéines motrices, la kinésine-5 et la dynéine, entraînent la séparation des pôles du fuseau.
Les protéines motrices de la kinésine-5 réticulent les extrémités positives des microtubules interpolaires qui se chevauchent. Ces protéines motrices dirigées vers l’extrémité positive génèrent une force vers l’arrière le long des microtubules, poussant les pôles du fuseau à l’écart. 
Les protéines motrices dynéines lient les extrémités positives des microtubules astraux avec les composants du cortex cellulaire. Ces protéines motrices dirigées vers l’extrémité négative génèrent une force, tirant les pôles du fuseau vers le cortex cellulaire.

<ol>
	<li>Alberts, Bruce. « Moteurs moléculaires. » Biologie moléculaire de la cellule. 4e édition. Bibliothèque nationale de médecine des États-Unis, 1er janvier 1970. [<a href="https://www.ncbi.nlm.nih.gov/books/NBK26888/">Source</a>]</li>
	<li>Joglekar, Ajit P, Kerry S Bloom et Ed Salmon. 2010. « Mécanismes de génération de force par des attaches kinétochores-microtubules end-on. » Opinion actuelle en biologie cellulaire 22 (1). Elsevier Ltd : 57 à 67. [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2822009/">Source</a>]</li>
	<li>Khodjakov, Alexey et Tarun Kapoor. 2005. « Flux de microtubules : à quoi est-ce bon ? » Current Biology 15 (23). Elsevier Inc. : R966 à R968. [<a href="https://www.sciencedirect.com/science/article/pii/S0960982205013928">Source</a>]</li>
</ol>

anaphases a et b

Les microtubules se forment par polymérisation bout à bout d’hétérodimères de tubuline. Les microtubules des kinétochores proviennent des pôles du fuseau et leurs extrémités positives se connectent aux kinétochores des chromatides sœurs. Les complexes protéiques Ndc80, présents sur le kinétochore, forment des liens de faible affinité avec l'extrémité positive de ces microtubules du kinétochore.

La dépolymérisation de l'extrémité positive libère des hétérodimères de tubuline de la région terminale du microtubule. À mesure que les sous-unités de tubuline sont perdues, les complexes Ndc80 se détachent et se rattachent aux sites situés en avant du segment dépolymérisant du microtubule. Le processus entraîne un déplacement vers les pôles, tirant le kinétochore et sa chromatide associée vers le pôle du fuseau.

Le flux des microtubules attire les chromatides vers les pôles du fuseau.

Les sous-unités de tubuline formant le réseau de microtubules se déplacent continuellement vers l'extrémité négative, présentant un flux de microtubules dirigé vers l'extrémité négative.

Le flux de microtubules se développe lorsque la dépolymérisation continue à l'extrémité négative est équilibrée par une polymérisation continue à l'extrémité positive. Un taux constant de dépolymérisation et de polymérisation maintient une longueur de microtubule fixe tandis que les sous-unités individuelles du réseau se déplacent vers l'extrémité de dépolymérisation.

Les microtubules des kinétochores soumis à un flux tirent les kinétochores et leurs chromatides associées dans la direction du flux, vers les pôles du fuseau.

Protéines motrices des microtubules – Dynein et Kinesin-5

Les dynéines sont des protéines motrices dirigées vers l'extrémité négative des microtubules. Les dynéines relient les extrémités positives des microtubules astraux aux composants cytosquelettiques du cortex cellulaire, positionnant ainsi les pôles du fuseau dans la cellule. Le mouvement dirigé vers l'extrémité négative des dynéines génère une force qui tire les pôles du fuseau vers le cortex cellulaire.

La kinésine-5 est une protéine motrice orientée vers le côté positif. La kinésine-5 interagit avec les extrémités positives des microtubules interpolaires anti-parallèles dans la zone médiane du fuseau. Ces moteurs de microtubules aident les microtubules interpolaires à glisser les uns sur les autres tout en générant une force écartant les pôles du fuseau.

Anaphases A et B

Les microtubules se forment par polymérisation de bout en bout d’hétérodimères de tubuline. Les microtubules de kinétochore proviennent des pôles du fuseau, et leur ...

Education

Enseignement

JoVE Core

Cell Biology

Biologie cellulaire

Unit 1

Unité 1

Cell Division

Division cellulaire

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

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 sides. The result is a more even distribution of genetic material before the cell finishes dividing.

Chromosome and Spindle Movement in Anaphase

chromosome-and-spindle-movement-in-anaphase

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 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.

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

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 anaphase A and anaphase B move chromosomes apart during cell division, with sister chromatids separating and spindle poles shifting to opposite sides.

Chromosome and Spindle Movement in Anaphase | JoVE K12

cell biology

JoVE Core Biologie cellulaire illustre les processus cellulaires complexes dans des leçons vidéos complètes mais faciles à comprendre. Cette collection se concentre sur les composants et fonctions essentiels de la cellule ; cela inclut les organelles et les membranes ainsi que le transport et le métabolisme énergétique cellulaire. Elle est complétée par nos vidéos de scientifiques à l'action qui démontrent l'application de la biologie cellulaire dans des expériences concrètes.

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

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.

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3.1.9-12.P

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3.1.9-12.Q

Chromosome and Spindle Movement in Anaphase

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