Name: phragmoplast in plant cell division
Uploaded: 2023-04-30T18:28:51.000Z
Duration: 1 min 59 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

Inheritance and Variation of Traits

3.1.9-12.D

The Phragmoplast

Les cellules végétales sont enfermées dans une paroi cellulaire rigide, ce qui rend difficile la division des cellules en se contractant de l’extérieur. Par conséquent, les cellules végétales se divisent en formant une nouvelle paroi cellulaire entre les deux noyaux filles de manière « à l’envers ». Une structure spécialisée chez les plantes appelée phragmoplaste guide la formation de la nouvelle paroi cellulaire.
Le plan de division cellulaire, qui est le futur site de formation de la paroi cellulaire, est marqué par une bande de préprophase composée de microtubules et de filaments d’actine qui se forme au cours de la phase G1 du cycle cellulaire. La bande préprophase s’assemble au niveau du cortex cellulaire et disparaît au début de la phase M.
Pendant la mitose, les chromosomes se séparent et commencent à se déplacer vers des pôles opposés. Aux pôles, l’enveloppe nucléaire se forme autour des chromosomes séparés et les fuseaux commencent à disparaître. Les microtubules restants du fuseau mitotique forment le phragmoplaste.
Les microtubules du phragmoplaste sont polaires, avec des extrémités positives près du plan équatorial et des extrémités négatives près des pôles.
Les corps de Golgi sécrètent de petites vésicules qui sont transportées par les protéines motrices le long des microtubules jusqu’au centre de la cellule. Ces vésicules sont remplies de polysaccharides et de glycoprotéines, deux composants importants nécessaires à la synthèse de nouvelles parois cellulaires. La fusion des vésicules forme une structure en forme de disque appelée plaque cellulaire précoce.
Les microtubules du phragmoplaste sont régénérés avec succès sur les marges libres de la plaque cellulaire, ce qui permet au phragmoplaste d’étendre la plaque latéralement. La nouvelle plaque cellulaire se joint aux parois cellulaires mères au site qui a été marqué par la bande de préprophase avant la phase M. La membrane plasmique fusionne avec la plaque cellulaire et une nouvelle paroi cellulaire se forme, séparant les deux cellules filles.

<ol>
	<li>Biologie moléculaire de la cellule, Alberts, 6e édition. Pages 997 à 999.</li>
	<li>Seagull, Robert W. et B. Gunning. « Le cytosquelette végétal. » Revues critiques en sciences végétales 8, n° 2 (1989) : 131-167.</li>
	<li>Hamada, Takahiro. « Organisation des microtubules et protéines associées aux microtubules dans les cellules végétales. » Dans Revue internationale de biologie cellulaire et moléculaire, vol. 312, pp. 1-52. Presse académique, 2014.</li>
	<li>Fosket, D. E. « Caractéristiques des cellules végétales qui sont importantes dans le développement. » Dans Croissance et développement des plantes. Une approche moléculaire. Academic Press San Diego, 1994.</li>
	<li>Casem, Merri Lynn, éd. Études de cas en biologie cellulaire. Presse académique, 2016.</li>
</ol>

le phragmoplaste

La division cellulaire est essentielle à la croissance et au développement de l'organisme. Dans les cellules animales, le fuseau central et ses protéines associées forment le corps médian, une structure qui joue un rôle essentiel dans la cytokinèse. Chez les plantes, le fuseau central, ainsi que les microtubules, l'actine et d'autres composants cellulaires, mûrissent pour devenir le phragmoplaste, nécessaire à la cytokinèse. Contrairement au corps médian stationnaire, le phragmoplaste se dilate de manière centrifuge, conduisant finalement à la formation d'une nouvelle paroi cellulaire.

Le phragmoplaste mature est en forme de beignet et contient une région externe avancée, une zone de transition médiane et une région interne en retard. Dans la région leader, de nouveaux microtubules sont assemblés en permanence. La nucléation des microtubules est initiée par le complexe annulaire γ-tubuline (γ-TuRC), qui contient six sous-unités : GCP1 à GCP6. Cependant, γ-TuRC ne peut pas interagir directement avec les microtubules ; par conséquent, augmin, un complexe protéique interagissant avec les microtubules, médie le recrutement de γ-TuRC dans les microtubules. Les microtubules présents dans le phragmoplaste servent de voies de transport aux vésicules sécrétoires produites par le corps de Golgi voisin.

Dans la zone de transition médiane, les vésicules se transforment initialement en structures de type tubule, puis s'interconnectent pour former un réseau tubulaire entrelacé. L'ajout continu de vésicules sécrétoires entraîne la croissance vers l'extérieur du réseau tubulaire jusqu'à ce qu'il rencontre la membrane cellulaire parentale. Les membranes des vésicules sont utilisées pour former la membrane plasmique des cellules filles, tandis que les biomolécules présentes dans les vésicules sont utilisées pour construire la plaque cellulaire présente entre les membranes des deux cellules filles.

Dans la région en retard, les microtubules se dépolymérisent, laissant derrière eux la partie mature de la plaque cellulaire. La plaque cellulaire entièrement formée se développe ensuite en la paroi cellulaire qui sépare les deux cellules filles. La polymérisation des microtubules à l'extrémité avant et la dépolymérisation des microtubules au niveau de la région en retard provoquent l'expansion vers l'extérieur du phragmoplaste et de la plaque cellulaire jusqu'à ce que cette dernière se joigne à la paroi cellulaire mère. Un dysfonctionnement des phragmoplastes peut entraîner la formation de cellules multinucléées et de phénotypes embryonnaires mortels.

Le phragmoplaste

La division cellulaire est essentielle à la croissance et au développement de l’organisme. Dans les cellules animales, le fuseau central et ses protéines associées forment le milieu du corps, un ...

Education

Enseignement

JoVE Core

Cell Biology

Biologie cellulaire

Unit 1

Unité 1

Cell Division

Division cellulaire

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

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. It provides a framework for building the new partition between the cells. This makes it a key structure in plant cell division.

Phragmoplast in Plant 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

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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

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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

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 phragmoplast helps plant cells complete division by guiding cytokinesis and the formation of a new cell wall between daughter cells.

Phragmoplast in Plant Cell Division | 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.

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from-molecules-to-organisms-structures-and-processes

From Molecules To Organisms: Structures And Processes

HS-LS1-4

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From Molecules to Organisms: Structures and Processes

BIO1.LS1.6

Minnesota Academic Standards in Science

3.1.1 9L.3.1.1.2

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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

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SC.912.L.16

SC.912.L.16.14

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B-LS1-4.

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3.1.9-12.P

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3.1.9-12.Q

Phragmoplast in Plant Cell Division

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