Name: chromosome copying in cell division
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 2 min 5 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

Chromosome Duplication

El material genético, el ADN, en una célula eucariota existe dentro del núcleo como estructuras lineales llamadas cromosomas.
Dentro de los cromosomas, el ADN bicatenario se envuelve principalmente alrededor de proteínas nucleares octaméricas llamadas histonas para formar nucleosomas. Varias proteínas no histonas también se asocian con el ADN, ayudando en el empaquetamiento del ADN.
Estos nucleosomas y proteínas no histonas se organizan para formar bobinas que se pliegan en bucles, en una matriz, formando cromatina empaquetada. El grado de compactación de la cromatina permite que un ADN extremadamente largo quepa dentro del núcleo. Durante la fase M, la cromatina se enrolla aún más para formar los cromosomas condensados.
La duplicación cromosómica implica la duplicación de toda la estructura de la cromatina, por lo que el ADN y las proteínas asociadas a la cromatina se duplican. La producción de histonas se incrementa para generar las proteínas adicionales necesarias para empaquetar el ADN recién sintetizado en cromosomas.
Replicar la estructura exacta de la cromatina del cromosoma duplicado es vital para la regulación génica. 
Dentro de los cromosomas, el nivel de empaquetamiento de la cromatina no siempre es uniforme. Los cromosomas contienen regiones con cromatina muy compacta llamada heterocromatina y regiones con cromatina poco compacta llamada eucromatina.
El ADN de la heterocromatina es inaccesible a la maquinaria de transcripción y, por lo tanto, los genes en esas regiones no se transcriben regularmente. Por el contrario, el ADN dentro de la eucromatina es más accesible y, por lo tanto, los genes en estas regiones se pueden transcribir. 
Esta importancia estructural y funcional de la cromatina hace que sea crucial que toda la estructura de la cromatina se reproduzca con precisión durante la duplicación cromosómica.

<ol>
	<li>Groth, Anja, Walter Rocha, Alain Verreault y Geneviève Almouzni. "Desafíos de la cromatina durante la replicación y reparación del ADN". Celda 128 (4)2007: 721–33. [<a href="https://www.sciencedirect.com/science/article/pii/S0092867407001298">Fuente</a>]</li>
	<li>Margueron, Raphaël y Danny Reinberg. "La estructura de la cromatina y la herencia de la información epigenética". Nature Reviews Genetics 11 (4)2010: 285–96. [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3760772/">Fuente</a>]</li>
</ol>

duplicación cromosómica

El proceso de duplicación cromosómica durante la división celular requiere la alteración de todo el genoma y el reensamblaje de la cromatina. La estructura de la cromatina debe heredarse, reensamblarse y mantenerse con precisión en las células hijas para garantizar la propagación del linaje.

La unidad básica de la cromatina es el nucleosoma, que consta de ADN envuelto alrededor de proteínas histonas octaméricas y tramos cortos de ADN conector que separa los nucleosomas individuales. Las proteínas histonas dentro del nucleosoma tienen sus extremos N-terminales que sobresalen del núcleo, proporcionando sitios para diversas modificaciones covalentes que regulan la estructura y función de la cromatina.

Durante la replicación, a medida que el ADN se desenrolla, los nucleosomas parentales se alteran y se liberan proteínas histonas. A medida que avanza la replicación y se forman las cadenas hijas, las histonas parentales y las proteínas histonas adicionales sintetizadas durante la fase S se ensamblan, lo que permite la formación de nucleosomas.

Las modificaciones postraduccionales de las histonas y otros dominios epigenéticos del ADN también se reproducen fielmente en el genoma hijo.

La estructura de la cromatina influye en la expresión genética.

Dentro de una célula, la mayor parte del genoma permanece inaccesible a los factores de transcripción, ya que las secuencias de ADN reguladoras y codificantes existen en su mayoría ocultas dentro de los nucleosomas. Para que un gen se exprese, es necesario crear sitios accesibles para que se unan los factores de transcripción y también modificar las histonas para reorganizar la estructura de la cromatina y crear un entorno permisivo para la transcripción.

Complejos de factores reguladores específicos participan en la apertura de regiones localizadas de la cromatina mediante el desplazamiento o la alteración de los nucleosomas. Las modificaciones postraduccionales de la cola de histonas sirven para mantener un estado transcripcional activo o inactivo. Modificaciones específicas en la cola de histonas pueden aliviar el nivel de compactación del ADN, facilitando la desestabilización y el desplazamiento de los nucleosomas, proporcionando acceso a la maquinaria de transcripción para influir en la expresión génica.

Duplicación cromosómica

El proceso de duplicación de cromosomas durante la división celular requiere la interrupción de todo el genoma y el reensamblaje de la cromatina. La estructura de la cromatina debe ser ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Cell Division

División celular

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 chromosome copying is essential for normal growth, repair, and reproduction in living organisms.

Chromosome Copying 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 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

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 chromosome copying works before cell division and how sister chromatids help daughter cells inherit the same genetic information.

Chromosome Copying 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

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.

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3.1.9-12.Q

Chromosome Copying in Cell Division

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