Name: cohesins in sister chromatid separation
Uploaded: 2023-04-30T18:28:50.000Z
Duration: 2 min 20 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

Cohesins

During S-phase of the cell cycle in eukaryotes, chromosomal duplication produces two identical copies of each chromosome called sister chromatids.
The sister chromatids formed are held together by a set of protein complexes called cohesins. The cohesin rings exist as clamps around the sister chromatids at multiple locations along their length, preventing them from drifting apart.
Cohesin complexes contain four subunits: Smc1, Smc3, Scc1, and Scc3. The Smc1 and Smc3 are coiled-coil proteins with a hinge domain at one end and an ATPase head domain at the other end. The hinge domains of Smc1 and Smc3 bind directly to each other, while an Scc1 subunit connected to an Scc3 subunit bridges the head domains of Smc1 and Smc3, forming a ring-like structure.
The hinge domain of the cohesin ring-structure can be triggered to open and close, facilitating cohesin loading on the chromosomes.
As cells progress through mitotic prophase, sister chromatid resolution takes place, involving dissociation of cohesin rings along the chromosomal arms while preserving those bound to the centromere region. The differential removal of cohesins causes the sister chromatids to become partially separated along their arms while remaining bound at their centromere.
Chromatid cohesion at the centromere facilitates the bi-orientation of chromosomes on the mitotic spindle during metaphase, ensuring correct microtubule attachment to the kinetochores of the sister chromatids.
At the onset of anaphase, a protease enzyme, separase, cleaves the Scc1 subunit, leading to the dissociation of cohesin from the chromosome.
Cohesin dissociation permits the segregation of sister chromatids during anaphase, where they are pulled apart by mitotic spindles to opposite poles of the cell, eventually leading to cell division and formation of two daughter cells.

cohesins

Cohesin protein complexes are a molecular glue that holds two sister chromatids together. They play an important role both in mitosis and meiosis. In mitosis, all cohesin complexes present on the chromosomes are removed before the start of the anaphase stage.
<h4>Cohesin complexes in Meiotic Division</h4>
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions&#8212; Meiosis I followed by Meiosis II &#8211; producing four daughter cells. Meiosis I includes the separation of homologous chromosomes, whereas Meiosis-II involves the separation of sister chromatids.
The Meiosis I cohesin complex consists of four subunits &#8211; Smc1, Smc3, Rec8 (replacing Scc1 from mitotic cohesin complex), and Scc3 &#8211; forming a ring-like structure.
During Meiosis I, entire chromosomes segregate towards the opposite poles as cohesin removal takes place only from the chromosomal arms. Cohesin is still maintained at the centromere region, allowing the sister chromatids to remain connected. During the metaphase I to anaphase I transition, the differential cohesin removal is facilitated by the separase-mediated cleavage of the Rec8 subunit of cohesins along the chromosomal arms. The centromeric Rec8 is protected from cleavage by association with a protector protein Shugoshin (Sgo1).
<h4>Cohesinopathies</h4>
Cohesins contribute to the maintenance of genomic stability. Mutations in genes coding for cohesin subunits or cohesin co-factors can lead to diseases called cohesinopathies. Cornelia de Lange syndrome (CdLS) and Roberts syndrome are two best-described cohesinopathies. CdLS is a neurodevelopmental disorder causing mental retardation, facial dysmorphism, upper limb abnormalities, and growth delay. Roberts syndrome results in craniofacial abnormalities, limb reduction, and growth retardation in affected patients.

Cohesin protein complexes are a molecular glue that holds two sister chromatids together. They play an important role both in mitosis and meiosis. In ...

Education

JoVE Core

Cell Biology

Unit 1

Cell Division

KEY TERMS AND CONCEPTS

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 function helps explain how cells manage accurate chromosome separation as they divide.

Cohesins in Sister Chromatid Separation

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 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 cohesins hold sister chromatids together and help cells separate chromosomes at the right time during mitosis and meiosis.

Cohesins in Sister Chromatid Separation | 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

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9-12.B.1.3

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Florida Department of Education

SC.912.L.16

SC.912.L.16.14

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South Carolina College and Career Ready Science Standards

B-LS1-4.

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New York State Science Learning Standards

HS-LS1-4.

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3.1.9-12.Q

Cohesins in Sister Chromatid Separation

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