Name: cell division and the contractile ring
Uploaded: 2023-04-30T18:28:51.000Z
Duration: 2 min 15 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

The Contractile Ring

The final step of the cell cycle that divides a cell into two daughter cells is called cytokinesis. Cytokinesis begins after chromosome separation in mitosis and ends when the cell divides.
The beginning of cytokinesis is marked by the appearance of a crease, called the cleavage furrow. Starting in anaphase, the furrow deepens and spreads to form a ring around the cell. This compression, which ultimately divides the cell into two, is generated by the contractile ring.
A protein called RhoA is the chief regulator of contractile ring assembly and function. To ensure the contractile ring is formed in the right place, RhoA is activated locally at the cell cortex, near the equator of the cell. RhoA, along with anaphase spindle fibers, also ensures that the contractile ring is formed at the right time, after chromosome segregation.
The contractile ring is made up of structural proteins, including actin filaments and myosin II filaments. RhoA activity results in the assembly of myosin II and anti-parallel actin filaments into the structure of the contractile ring. RhoA promotes localized actin filament polymerization which is necessary for the contractile ring formation.
The contractile ring components generate the force necessary to divide the cell. One mechanism of contraction involves myosin motor activity. Here, myosin filaments move toward the plus end of adjacent antiparallel actin filaments.&#160; This activity pulls the anti-parallel actin, causing them to slide past one another, contracting the ring.
The contraction of the ring continues until it pinches off two new cells. The ring is degraded once the new cells are formed.
Inefficient or absence of contractile ring formation can lead to abnormal cell division, impaired growth, and the potential for tumor formation.

the contractile ring

Contractiele ringen zijn samengesteld uit microfilamenten en zijn verantwoordelijk voor het scheiden van de dochtercellen tijdens cytokinese. De assemblage van de contractiele ringen verloopt samen met andere celcyclusgebeurtenissen; Er zijn echter zeer weinig mechanistische details bekend over de timing en coördinatie van de contractiele ringen met de celcyclus.

Een kleine GTPase, RhoA, regelt de functie en montage van de contractiele ring. RhoA behoort tot de Ras-superfamilie van eiwitten. De activering van formines door RhoA bevordert de vorming van actinefilamenten, terwijl de activering van meerdere proteïnekinasen door RhoA de assemblage en contractie van myosine II stimuleert. De kinasen fosforyleren de lichte keten van myosine en stimuleren de filamentvorming en motorische activiteit. Naast actine en myosine II (actomyosine) zijn ook septinefilamenten betrokken bij de vorming van contractiele ringen. Septinefilamenten stabiliseren de contractiele ring en spelen een belangrijke rol bij cytokinese van gist.

De activering van RhoA wordt gereguleerd door een guanine-nucleotide-uitwisselingsfactor (Rho-GEF). Dit eiwit wordt aangetroffen in het cortexgebied, de plaats van toekomstige celdeling. De inactieve vorm van RhoA is gebonden aan het GDP. Rho-GEF wisselt het aan RhoA gebonden BBP uit met GTP. De binding van GTP activeert RhoA, wat op zijn beurt de vorming van contractiele ringen veroorzaakt.

RhoA reguleert ook de activiteit van het scaffold-eiwit anilline, een essentiële speler bij de vorming van contractiele ringen. Hoewel RhoA wordt beschouwd als de belangrijkste activator voor de assemblage van de contractiele ring, fungeert anilline als de belangrijkste organisator van de ring door binding met actine, myosine II, membraanfosfolipiden, septine en andere structurele en regulerende componenten die betrokken zijn bij de vorming van contractiele ringen.

De voortdurende krimp van de contractiele ring betekent dat er geleidelijk een kleiner aantal actomyosinefilamenten nodig is om een ring van dezelfde dikte te vormen; daarom vindt gelijktijdige demontage van de actomyosinefilamenten plaats terwijl de ring samentrekt. Tijdens de laatste stadia van de cytokinese rijpen de contractiele ring en de centrale spil met daarin compacte microtubuli om het middenlichaam en de middenlichaamsring te vormen. De middenlichaamsring voert vervolgens de abscissie van de oudercel uit, wat resulteert in de vorming van twee dochtercellen.

Contractile rings are composed of microfilaments and are responsible for separating the daughter cells during cytokinesis. Contractile ring assembly ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Cell Division

Celdeling

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

De Contractiele 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 division. It shows how cell structures and protein movement work together during cytokinesis.

Cell Division and the Contractile Ring

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

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 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 the contractile ring forms during cytokinesis and uses actin and myosin to pinch one cell into two daughter cells.

Cell Division and the Contractile Ring | 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

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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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

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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

Centrosome Duplication

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

Determining the Plane of Cell Division

The Phragmoplast

Distribution of Cytoplasmic Content

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DNA Packaging

DNA as a Genetic Template

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Structure of a Gene

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3.1.9-12.P

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What is Meiosis?

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Meiosis I

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Meiosis II

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Crossing Over

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Nondisjunction

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Base-pairing and DNA Repair

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

Cell Division and the Contractile Ring

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