Name: how plant cells build a new wall
Uploaded: 2021-04-07T12:12:02.000Z
Duration: 1 min 59 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

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

From Molecules to Organisms: Structures and Processes

HS-LS1-4

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

Molecular Biology

Biologie moléculaire

Unit 2

Unité 2

Cell Division

Division cellulaire

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

how plant cells build a new wall

Plant cells build a new wall during cytokinesis with help from the phragmoplast. This plant structure forms from the central spindle and related cell parts as the cell finishes dividing. In animal cells, the comparable structure is the midbody, but in plants the phragmoplast expands outward to guide new wall formation.

The mature phragmoplast has a donut-like shape. It has an outer leading region, a middle transition zone, and an inner lagging region. New microtubules are assembled continuously in the leading region. Microtubule nucleation begins with the gamma-tubulin ring complex, or gamma-TuRC, which contains six subunits called GCP1 through GCP6. Because gamma-TuRC cannot attach to microtubules on its own, augmin, a microtubule-interacting protein complex, helps recruit it to the microtubules.

The microtubules in the phragmoplast act as tracks for secretory vesicles from the nearby Golgi body. In the middle transition zone, these vesicles first change into tubule-like structures. They then connect to form an intertwined tubular network. As more vesicles are added, the network grows outward until it reaches the parental cell membrane.

The vesicle membranes become the plasma membrane of the daughter cells. The materials inside the vesicles help build the cell plate between the two daughter-cell membranes. In the lagging region, the microtubules break down, leaving the mature part of the cell plate behind. The finished cell plate then develops into the cell wall that separates the two daughter cells.

This outward growth depends on microtubules being built at the leading end and broken down at the lagging end. If phragmoplast function fails, cells can become multinucleated. It can also lead to embryonic lethal phenotypes.

How Plant Cells Build a New Wall

mitosis and cytokinesis

Mitosis and Cytokinesis Stages

Mitosis and cytokinesis are the two main steps of cell division. Mitosis is the process that divides the nucleus, while cytokinesis splits the rest of the cell. During mitosis, the cell’s genetic material is separated into two sets. This helps form two new nuclei with the same genetic information. Cytokinesis then completes division by separating the cytoplasm, which creates two daughter cells. These stages work together to make cell division possible in growing and repairing tissues.

duplication of chromatin structure

Chromatin Rebuilding During DNA Replication

Chromatin rebuilding during DNA replication helps cells copy DNA and pass on chromosome structure to daughter cells. During cell division, the genome must be disrupted and then reassembled across the whole chromosome. This process allows chromatin to be inherited, rebuilt, and maintained in new cells. The basic unit of chromatin is the nucleosome. A nucleosome contains DNA wrapped around an octamer of histone proteins, with short linker DNA between neighboring nucleosomes. The histone proteins...

cohesins

Cohesins in Meiosis and Genetic Disorders

Cohesin protein complexes act like molecular glue that keeps sister chromatids together. They are important in both mitosis and meiosis. In mitosis, cohesin complexes are removed from chromosomes before anaphase begins. Meiosis has two rounds of chromosome separation. Meiosis I separates homologous chromosomes, while Meiosis II separates sister chromatids. This process produces four daughter cells. The Meiosis I cohesin complex is made of four subunits: Smc1, Smc3, Rec8, and Scc3. Rec8...

condensins

How Condensins Shape Mitotic Chromosomes

Condensins shape chromosomes during mitosis, the stage when a cell divides. These large protein complexes use ATP, the cell’s energy molecule, to help turn loose post-interphase DNA into compact, separate chromosomes. They organize and segregate chromosomal DNA so it can be passed on correctly. Plant and animal cells contain two condensin complexes: condensin I and condensin II. Each complex has five subunits. Two are SMC, or Structural Maintenance of Chromosomes, subunits. One is a kleisin...

the mitotic spindle

How the Mitotic Spindle Separates Chromosomes

The mitotic spindle is a microtubule-based structure that helps separate chromosomes during cell division. It forms in eukaryotic cells and moves sister chromatids to opposite ends of the parent cell. This leaves each new cell nucleus with the correct genetic material. A bipolar spindle has two poles, and that shape is important for chromosome segregation. In many animal cells, two centrosomes are present when mitosis begins. Each centrosome helps organize a circular set of microtubules at one...

centrosome duplication

Centrosome Duplication in the Cell Cycle

Centrosome duplication is a key part of the animal cell cycle. The centrosome is the main microtubule organizing center, or MTOC, in animal cells. It contains two cylindrical centrioles at its core. Each centriole has nine sets of three microtubules held together by proteins. The two centrioles sit at right angles and are surrounded by the pericentriolar matrix, or PCM, a shapeless protein cloud. Duplication starts early in the cell cycle so each daughter cell can receive a centrosome after...

microtubule instability

Microtubule Growth and Shrinkage

Microtubules are hollow, cylindrical filaments in the cell. They are about 25 nm wide and can range from 200 nm to 25 μm in length. Their main building blocks are GTP-bound tubulin subunits that form αβ-heterodimers, which then assemble into protofilaments. These protofilaments join by lateral bonds to create stable microtubule cylinders. Microtubules are highly dynamic because they repeatedly assemble and break down. They can even grow on one end while shrinking on the other at the same time.

spindle assembly

How the Mitotic Spindle Forms

The mitotic spindle forms through centrosome-mediated, chromatin-mediated, and microtubule-mediated pathways. These pathways often work at the same time. Together, they build a strong spindle apparatus for cell division. In most cells, centrosomes are the main sites where microtubules begin to grow. During the G2 to prophase transition, centrosomes mature and make more microtubules. The growing microtubules extend from both centrosomes, and their plus-ends search for chromosomes by attaching...

attachment of sister chromatids

Kinetochore-Microtubule Binding in Mitosis

Kinetochore-microtubule binding helps chromosomes line up and separate during mitosis. After the nuclear envelope breaks down, condensed chromosomes are exposed to the bipolar microtubules of the mitotic spindle. The kinetochore is a large, disc-shaped protein complex at the centromere region of each sister chromatid, and it serves as the microtubule binding site. Usually, the plus-end of a single microtubule inserts into the kinetochore. In some cases, a kinetochore first makes lateral...

forces acting on chromosomes

Chromosome Movement During Mitosis

Chromosome movement during mitosis depends on several small forces that act at different times and positions in the cell. In prometaphase, these forces help chromosomes move to the equatorial plane and line up at the metaphase plate. Because the forces change with location and stage, chromosome behavior also changes as mitosis continues. Microtubules and motor proteins create two main kinds of force on chromosomes: poleward force and anti-poleward force, also called polar-ejection force.

separation of sister chromatids

Anaphase Start and Chromatid Release

Anaphase starts when sister chromatids are released from one another and pulled toward opposite spindle poles. Before that happens, cohesion along the chromosomal arms is reduced from prophase to metaphase, which helps the sister chromatids resolve. A residual cohesin link still holds them together until the metaphase-to-anaphase transition. This leftover connection helps prevent early separation and reduces the risk of aneuploidy, or the wrong number of chromosomes, in daughter cells. At the...

the spindle assembly checkpoint

How Cells Safeguard Chromosome Separation

The spindle assembly checkpoint helps cells safeguard chromosome separation during anaphase. It acts as a molecular surveillance system. The checkpoint checks whether the steps needed for chromosome segregation are complete before the cell moves on. Many proteins work together to control this checkpoint. If mutations affect these proteins, a cell may enter anaphase too early. Chromosomes can then separate before the needed steps are finished. When this happens, the daughter cells may receive...

anaphase a and b

Chromatid Movement by Microtubule Forces

Chromatid movement during anaphase depends on microtubule forces at the spindle. Kinetochore microtubules grow from the spindle poles, and their plus ends attach to kinetochores on sister chromatids. The kinetochore protein complex Ndc80 makes low-affinity links with the microtubule plus end.

the contractile ring

How Cells Build the Contractile Ring

Contractile rings are built from microfilaments and help separate daughter cells during cytokinesis. This ring forms as the cell cycle moves forward, but the exact timing and coordination with other cell cycle events are still not fully understood. RhoA, a small GTPase in the Ras superfamily, controls contractile ring assembly and function. The inactive form of RhoA is bound to GDP. A guanine nucleotide exchange factor, or Rho-GEF, is located in the cortex region, where the next cell division...

determining the plane of cell division

How Cells Set the Division Plane

How cells set the division plane during cell division affects daughter cell size and, in many cases, cell fate. The plane of division is perpendicular to the plane of chromosome segregation. Different organisms use different cues to place it, based on their shape and needs. In animal cells, the cleavage furrow forms along the division plane from the cell cortex, the area just below the plasma membrane. The mitotic spindle is the main guide for this position. If the spindle axis changes, the...

the phragmoplast

Plant cells build a new wall during cytokinesis with help from the phragmoplast. This plant structure forms from the central spindle and related cell parts as the cell finishes dividing. In animal cells, the comparable structure is the midbody, but in plants the phragmoplast expands outward to guide new wall formation. The mature phragmoplast has a donut-like shape. It has an outer leading region, a middle transition zone, and an inner lagging region. New microtubules are assembled...

distribution of cytoplasmic content

How Organelles Are Split During Cytokinesis

Cytokinesis splits a cell’s chromosomes and organelles into two daughter cells. Before cell division, organelles grow and divide. They cannot be made from scratch, so each daughter cell must inherit at least one copy to survive. Many details of this organelle sorting process are still not fully known. The cytoplasm contains organelles, salts, proteins, and water. Small organelles such as peroxisomes and lysosomes can be shared by simple diffusion. Because cells contain many copies of these...

anaphase promoting complex

APC Activates Chromosome Separation

The anaphase-promoting complex, or APC, helps control cell cycle progression by destroying specific proteins at the right time. These proteins are tagged with ubiquitin by ubiquitin ligases and then broken down by the proteasome. The SCF (Skp1/Cullin/F-box) complex and APC are two major ubiquitin ligases involved in this process. SCF stays active throughout the cell cycle, but APC turns on during the metaphase-to-anaphase transition. APC becomes active when Cdc20 or Cdh1 binds to it. These...

key terms and concepts

Learn how the phragmoplast helps plant cells complete cytokinesis, guide vesicles, and form the new cell plate and cell wall.

How Plant Cells Build a New Wall | JoVE K12

molecular biology

JoVE Core Biologie Moléculaire illustre les processus moléculaires au sein de la cellule grâce à des leçons vidéos claires et concises. Les applications de ces concepts sont ensuite démontrées grâce à des expériences concrètes en laboratoire.

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS1-4.

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

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Cell Structure

Background
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Visualizing Onion and Cheek Cells
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What are Cells?

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

The Central Dogma

The DNA Helix

Nucleic Acids

DNA as a Genetic Template

Structure of a Gene

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Chromosome Structure

Base-pairing and DNA Repair

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Conservation of Protein Domains

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Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Globular and Fibrous Proteins

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Intrinsically Disordered Proteins

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Protein Complex Assembly

Protein and Protein Structures

Conjugated Proteins

Proteins: From Genes to Degradation

Amyloid Fibrils

What are Proteins?

Proteins are polymers of amino acids linked together by peptide bonds. Proteins and polypeptides are interchangeably used to refer to long chains of amino ...

Ligand Binding Sites

Protein Organization

Proteins are polymers of amino acid residues. They are versatile and responsible for different cellular functions, including DNA replication, molecular ...

Protein-Protein Interfaces

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to ...

Conserved Binding Sites

Cofactors and Coenzymes

Enzymes are proteins made of amino acids. The functional group of each constituent amino acid catalyzes a wide variety of chemical reactions via ionic ...

Cooperative Allosteric Transitions

Protein Kinases and Phosphatases

GTPases and their Regulation

Covalently Linked Protein Regulators

protein-complexes-with-interchangeable-parts

Protein Complexes with Interchangeable Parts

Mechanical Protein Function

Structural Protein Function

Protein Networks

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. [Assessment Boundary: Assessment does not include identification of specific cell or tissue types, whole body systems, specific protein structures and functions, or the biochemistry of protein synthesis.]

HS-LS1-1

Levels of Organization

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth&#x27;s biosphere. ...

Animal and Plant Cell Structure

Animal and plant cells not only differ in their structure, function, and mode of nutrition but also in how they reproduce, specialize, and organize into ...

structural-organization-of-the-human-body-an-overview

Structural Organization of the Human Body: An Overview

It is convenient to consider the body&#39;s structures in terms of fundamental levels of organization that increase in complexity: subatomic particles, ...

Overview of Human Digestion

The human body contains a monogastric digestive system. In a monogastric digestive system, the stomach only contains one chamber in which it digests food. ...

Anatomy of the Intestines

Although digestion of proteins, carbohydrates, and lipids may begin in the stomach, it is completed in the intestine. The absorption of nutrients, water, ...

Accessory Organs

Accessory organs are those that participate in the digestion of food but do not come into direct contact with it like the mouth, stomach, or intestine do. ...

Lipid Digestion

Lipids are large molecules that are generally not water-soluble. Since most of the digestive enzymes in the human body are water-based, there are specific ...

Protein Digestion

Protein digestion begins in the stomach, where the highly acidic environment can easily disrupt protein structure by exposing the peptide bonds of ...

Carbohydrate Digestion

Carbohydrate digestion and metabolism break down simple and complex carbohydrates from food into saccharides (i.e., sugars) for the body to use as energy. ...

What is a Nervous System?

Overview

The nervous system is the collection of specialized cells responsible for maintaining an organism&rsquo;s internal environment and coordinating ...

The Parasympathetic Nervous System

Overview

The parasympathetic nervous system is one of the two major divisions of the autonomic nervous system. This parasympathetic system is responsible ...

The Sympathetic Nervous System

Overview

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Oogenesis

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What is a Sensory System?

Sensory systems detect stimuli&mdash;such as light and sound waves&mdash;and transduce them into neural signals that can be interpreted by the nervous ...

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ...

What is the Skeletal System?

Overview

The adult human skeleton comprises 206 bones that are connected through cartilage, tendons, and ligaments. The skeleton provides a rigid ...

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An Introduction to the Zebrafish: Danio rerio

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Physiology of the Circulatory System

Homeostasis
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Anatomy of the Circulatory System

The human circulatory system consists of blood, blood vessels that carry blood away from the heart, around the body, and back to the heart, and the heart ...

Measuring Blood Pressure
ExpandTo prepare for the blood pressure exercise, simply place the appropriate number of alcohol swabs, sphygmomanometers, and ...

Anatomy of the Heart

The human heart is made up of three layers of tissue that are surrounded by the pericardium, a membrane that protects and confines the heart. The ...

Measuring Circulatory System Function in Humans
ExpandBefore starting the experiment go to the front of the room and collect an alcohol swab, a ...

Blood Flow

Blood is pumped by the heart into the aorta, the largest artery in the body, and then into increasingly smaller arteries, arterioles, and capillaries. The ...

Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. [Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.] [Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.]

HS-LS1-2

How Plant Cells Build a New Wall

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