Name: chromatid pulling in cell division
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 2 min 17 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

Separation of Sister Chromatids

Al final de la metafase, los cromosomas biorientados se alinean en la placa de la metafase. Durante esta fase, los complejos de anillos de proteínas cohesinas mantienen unidas a las cromátidas hermanas en la región del centrómero y evitan que se separen.
La progresión de la metafase a la anafase se desencadena por la fosforilación inducida por la ciclina-Cdk de una enzima ubiquitina ligasa de múltiples subunidades, el complejo promotor de la anafase, también conocido como ciclosoma o APC/C. La APC/C fosforilada se une a una proteína, Cdc20, formando un complejo activo.
El complejo activo APC/C reconoce una proteína inhibidora llamada securina que se une a una enzima proteasa llamada separasa. Antes de este reconocimiento, la securina inhibe la actividad de la separasa.
El complejo activo APC/C marca la securina con la proteína ubiquitina, dirigiéndose a ella para la degradación proteasómica. La destrucción de la securina libera separasa.
El complejo ciclina-Cdk también regula negativamente la actividad de la separasa no unida a través de la fosforilación inhibitoria.
El complejo activo APC/C provoca la ubiquitinación de las ciclinas, dirigiéndose a ellas para la degradación proteasómica. La destrucción de la ciclina elimina la actividad enzimática de las quinasas dependientes de ciclina o Cdks.
La inactivación de Cdks permite que las enzimas fosfatasa desfosforilan la separasa y evita la refosforilación inhibitoria de la separasa mediada por Cdk. La desfosforilación permite que la enzima separasa escinda el complejo de anillos de cohesina que mantiene unidas a las cromátidas hermanas.
La escisión de la cohesina da lugar a la pérdida absoluta de la cohesión de las cromátidas hermanas, lo que marca la transición de la metafase a la anafase. La pérdida de cohesión permite que las cromátidas hermanas se separen y se muevan a polos opuestos del huso.

<ol>
	<li>Claire Acquaviva y Jonathon Pines. 20016. "El complejo promotor de la anafase/ciclosoma: APC/C". Revista de Ciencia Celular. 119: 2401-2404. [<a href="https://jcs.biologists.org/content/119/12/2401#sec-2">Fuente</a>]</li>
	<li>Frank Uhlmann, Friedrich Lottspeich y Kim Nasmyth. 1999. "La separación de cromátidas hermanas al inicio de la anafase es promovida por la escisión de la subunidad de cohesina Scc1." Nature 400 (6739). Grupo Editorial Nature: 37–42. [<a href="https://mcb.berkeley.edu/courses/mcb230/WEB/PAPERS/SCC1.pdf">Fuente</a>]</li>
	<li>Farr, Katie A. y Orna Cohen‐Fix. "La transición de la metafase a la anafase: un caso de destrucción productiva". Revista europea de bioquímica 263, núm. 1 (1999): 14-19.</li>
	<li>Fang, Guowei, Hongtao Yu y W. Kirschner. "Control de las transiciones mitóticas por el complejo promotor de la anafase". Transacciones filosóficas de la Royal Society de Londres. Serie B: Ciencias Biológicas 354, no. 1389 (1999): 1583-1590.</li>
</ol>

separación de cromátidas hermanas

En la transición de la profase a la metafase, hay una reducción de la cohesión a lo largo de los brazos cromosómicos, lo que resulta en la resolución de las cromátidas hermanas. Sin embargo, quedan conexiones de cohesina residuales para mantener unidas a las cromátidas hermanas hasta la transición de la metafase a la anafase. La conexión residual evita cualquier separación prematura de las cromátidas hermanas, bloqueando los riesgos de aneuploidía dentro de las células hijas.

Al inicio de la anafase, se activa la separasa, una enzima proteolítica. La separasa activada escinde la subunidad Scc1 de los anillos de cohesina residuales, lo que resulta en una pérdida total de cohesión. Las cromátidas hermanas se separan en ausencia de fuerza para mantenerlas unidas. La falta de cohesión permite que las fuerzas polares, que se esfuerzan a lo largo de los microtúbulos, tiren de las cromátidas separadas hacia los polos del huso.

En las primeras mitosis, el punto de control del ensamblaje del huso (SAC) prohíbe que el complejo o ciclosoma promotor de la anafase (APC/C) ubiquitine proteínas, como la securina y las ciclinas de fase M, cuya degradación es necesaria para la anafase. Solo cuando cada cromosoma se alinea correctamente en el huso mitótico, el SAC se desactiva para permitir la fosforilación y activación de las subunidades reguladoras de APC/C: CDC20 y CDH1.

El CDC20 es fosforilado por Cdk1/ciclina B para formar APC/C-CDC20 activo. El APC/C-CDC20 activo luego cataliza la degradación de securina, ciclina A y ciclina B para promover la transición a anafase. Debido a que la actividad de Cdk depende de la ciclina, la degradación de la ciclina B da como resultado la pérdida de la actividad de Cdk1. La pérdida del complejo Cdk1/ciclina B inactiva APC/C-CDC20 pero activa otra subunidad reguladora, APC/C-CDH1, que señala la finalización de la transición de metafase a anafase. El activo APC/C-CDH1 facilita la salida mitótica y estabiliza la fase G1 posterior evitando la acumulación prematura de ciclinas mitóticas.

El cambio en las actividades de APC/C-CDC20 y APC/C-CDH1 tiene dos consecuencias importantes. En primer lugar, estas subunidades reguladoras desencadenan especificidades de sustrato superpuestas pero distintas y, por lo tanto, promueven una transición ordenada del ciclo celular. En segundo lugar, CDC20 y CDH1 se regulan mediante diferentes mecanismos. Cuando APC/C-CDC20 está activo, CDH1 sufre una fosforilación inhibidora por la ciclina B/Cdk1, impidiendo que se una a APC/C. Por el contrario, la actividad de CDC20 es inhibida por un complejo de punto de control mitótico, una multiproteína (BUBR1, BUB3, CDC20 y MAD2) activada por el SAC.

Separación de cromátidas hermanas

En la transición de la profase a la metafase, se produce una reducción de la cohesión a lo largo de los brazos cromosómicos, lo que da lugar a la resolución de ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Cell Division

División celular

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 chromosomes.

This process is essential for accurate chromosome distribution. If sister chromatids do not separate properly, the new cells may not get the right genetic information. Understanding this step helps explain how cells copy and pass on DNA during division.

Chromatid Pulling 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 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

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 sister chromatids separate during cell division and move to opposite sides of the cell so daughter cells receive the correct genetic material.

Chromatid Pulling in Cell Division | JoVE K12

cell biology

JoVE Core Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

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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Interphase

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The Cell Cycle Control System

Positive Regulator Molecules

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Chromosome Duplication

Cohesins

Condensins

The Mitotic Spindle

Centrosome Duplication

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Attachment of Sister Chromatids

Forces Acting on Chromosomes

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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DNA Packaging

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Organization of Genes

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Chromosome Structure

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Chromosome Replication

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The Nucleosome

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Karyotyping

Proteins: From Genes to Degradation

The DNA Helix

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The Central Dogma

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3.1.9-12.P

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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

Chromatid Pulling in Cell Division

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