Name: cell division: mitosis and cytokinesis
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 35 s
Channel: JoVE

A mitose é uma forma de divisão celular em que o material genético de uma célula é dividido entre duas células-filhas. 
Primeiro, durante a prófase, a cromatina nucléica se condensa em cromossomos em forma de x compostos de pares de cromátides irmãs ligadas nas junções do centrômero.
Ao mesmo tempo, os centrossomas migram para lados opostos da célula. Ao fazê-lo, as hastes dos microtúbulos começam a crescer a partir de cada uma, formando um aparelho de fuso semelhante a uma teia.
Em seguida, o envelope nuclear se dissolve durante a prometáfase e as estruturas proteicas, denominadas cinetocoros, aparecem em ambos os lados dos centrômeros, uma para cada cromatina.
Uma vez que esses cinetocoros se formam, os microtúbulos internos que se estendem se prendem a eles, com cada cromátide irmã sendo amarrada a um pólo celular diferente.
Na metáfase, o aparelho do fuso reorganiza os cromossomos para que sejam orientados em uma linha fixa ao longo do equador da célula.
Com a anáfase, os microtúbulos fixos do cinetócoro encurtam e as cromátides irmãs são separadas. Essas e outras dinâmicas de microtúbulos também alongam a célula.
Durante a telófase, o aparelho do fuso se dissolve, as cromátides se soltam e os envelopes nucleares são reformados.
Finalmente, a célula é dividida citoplasmicamente pela citocinese, formando um par de células geneticamente idênticas ao seu precursor.

<ol>
	<li>Guertin, David A., Susanne Trautmann e Dannel McCollum. "Citocinese em eucariotos." Microbiol. Mol. Biol. Rev. 66, nº 2 (1º de junho de 2002): 155–78.</li>
</ol>

mitose e citocinese

Mitosis And Cytokinesis

Nos eucariontes, o ciclo de divisão celular é dividido em processos celulares distintos e coordenados que incluem crescimento celular, replicação de DNA/duplicação de cromossomos, distribuição de cromossomos para células-filhas e, finalmente, divisão celular. O ciclo celular é fortemente regulado por seus sistemas reguladores, bem como por sinais extracelulares que afetam a proliferação celular. Os processos do ciclo celular ocorrem durante aproximadamente 24 horas (em células humanas típicas) e em dois estágios principais distinguíveis. O primeiro estágio é a replicação do DNA, durante a fase S da interfase. O segundo estágio é a fase mitótica (M), que envolve a separação dos cromossomos duplicados em dois novos núcleos (mitose) e a divisão citoplasmática (citocinese). As duas fases são separadas por intervalos (lacunas G1 e G2), durante os quais a célula se prepara para replicação e divisão. O Processo de Mitose A mitose pode ser dividida em cinco estágios distintos – prófase, prometáfase, metáfase, anáfase e telófase. A citocinese, que começa durante a anáfase ou telófase (dependendo da célula), faz parte da fase M, mas não faz parte da mitose. Prófase À medida que a célula entra na mitose, seus cromossomos replicados começam a condensar-se e tornam-se visíveis como estruturas filiformes com a ajuda de proteínas conhecidas como condensinas. O aparelho do fuso mitótico começa a se formar entre os centrossomas – que foram duplicados durante a fase S – e migra para pólos opostos da célula. O fuso é composto de estruturas filamentosas chamadas microtúbulos, compostas por monômeros da proteína tubulina. Os microtúbulos fusiformes começam a se estender em direção aos cromossomos condensados. O nucléolo, um componente do núcleo que produz ribossomos, desaparece, indicando a ruptura iminente do núcleo. Prometáfase Durante a prometáfase, os filamentos dos microtúbulos do aparelho do fuso continuam a crescer e os cromossomos terminam de se condensar. O envelope nuclear se rompe completamente, liberando os cromossomos. Alguns dos microtúbulos ligam-se aos cromossomos liberados, ligando-se a uma estrutura proteica chamada cinetocoro, que está presente no centrômero de cada par de cromátides irmãs. Os microtúbulos fusiformes de pólos opostos ligam-se aos cinetocoros e capturam os pares condensados de cromátides irmãs. Os microtúbulos fusiformes que não se ligam aos cromossomos - microtúbulos polares e astrais - ajudam a separar os fusos e a ancorar os pólos do fuso à membrana celular. Metáfase Os microtúbulos fusiformes alinham cada par de cromátides irmãs totalmente condensadas ao longo do equador da célula - na placa metafásica. A célula agora está pronta para se dividir. Anáfase Os microtúbulos dos pólos opostos do fuso, que estão ligados à estrutura do cinetocoro, encurtam e separam as cromátides irmãs no centrômero. As proteínas de coesão que mantêm as cromátides unidas agora se decompõem. O encurtamento dos microtúbulos do cinetocoro faz com que cada cromátide do par - agora chamados de cromossomos - migre para um pólo oposto. Telófase Quando os cromossomos atingem os pólos opostos da célula, eles se descondensam e se desenrolam para formar a cromatina. Os filamentos fusiformes dos microtúbulos despolimerizam-se em seus monômeros de tubulina, que são então utilizados como elementos do citoesqueleto nas células-filhas. Os envelopes nucleares se remontam em torno de cada conjunto de cromossomos. Citocinese Durante a citocinese em células animais, os filamentos de actina formam um anel contrátil na membrana plasmática para criar um sulco de clivagem, que eventualmente comprime a célula em duas. Nas células vegetais, vesículas do aparelho de Golgi transportando glicose, enzimas e proteínas estruturais unem-se para formar uma nova placa celular no local da antiga placa metafásica. A placa celular em crescimento se funde com as membranas plasmáticas de cada lado, formando eventualmente uma nova parede celular que divide a célula em duas. A mitose agora está completa, gerando duas células-filhas idênticas à célula-mãe. Na maioria das células humanas, a mitose é responsável por cerca de uma hora do ciclo celular de aproximadamente 24 horas.

Mitose e Citocinese

Nos eucariotos, o ciclo de divisão celular é dividido em processos celulares distintos e coordenados que incluem crescimento celular, replicação de DNA / cromossomo ...

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Anatomy and Physiology

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Essential Cellular Processes

Processos Celulares Essenciais

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

cell division: mitosis and cytokinesis

Cell division depends on mitosis and cytokinesis. Mitosis is the stage when the cell’s nucleus divides and the copied chromosomes are separated into two sets. Cytokinesis is the step that follows and splits the cell into two daughter cells.

These two processes work together to make sure each new cell receives genetic material and its own cytoplasm. Mitosis keeps the chromosome sets organized, while cytokinesis finishes the division of the whole cell. Together, they create two separate cells from one starting cell.

Cell Division: Mitosis and Cytokinesis

the central dogma

Central Dogma: DNA to Protein

The central dogma explains how genetic information flows in cells from DNA to RNA to protein. It is a core idea in molecular biology and helps show how genes influence cell function. DNA stores the instructions. During transcription, a cell copies a gene into RNA, which is a related nucleic acid. That RNA message can then be used in translation to build a protein. Proteins carry out many jobs in cells and help determine traits. The central dogma links the genetic code in DNA to the molecules...

replication in eukaryotes

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Eukaryotic DNA copying happens at replication forks, where the two DNA strands separate and new strands are built. This process lets a cell make an exact copy of its genetic material before it divides. The transcript explains that eukaryotic replication follows the same basic steps seen in other DNA replication systems, but it takes place in cells with a nucleus. The replication machinery works on each separated strand as a template, so the new DNA matches the original sequence. This topic is...

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RNA types play different roles in gene expression. RNA, or ribonucleic acid, helps carry and use genetic information in cells. The main types discussed here are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA, or mRNA, carries the genetic code from DNA to the ribosome. The ribosome is the site where proteins are made. Ribosomal RNA, or rRNA, is a key part of the ribosome itself. Transfer RNA, or tRNA, brings the correct amino acids to the ribosome during protein building. These...

transcription

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Transcription is the process of making RNA from a DNA template. It is a key step in gene expression, because cells use the DNA sequence to build an RNA copy that can carry the message forward. During transcription, RNA polymerase binds to DNA and reads one strand as the template. The enzyme links RNA nucleotides together in the correct order to form a growing RNA molecule. This copying step does not make DNA; it produces RNA. The transcript focuses on the central idea of transcription as DNA...

translation

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Cell Cycle Stages in Cell Growth

The cell cycle is the process that controls cell growth and division. It explains how one cell makes two new cells. This process helps cells grow and reproduce.

interphase

Interphase and Cell Growth

Interphase is the part of the cell cycle when a cell grows and prepares to divide. It is a major stage of the cell cycle, and it comes before cell division begins. During interphase, the cell carries out its normal functions. It also copies its DNA so each new cell can receive a full set of genetic material. The cell may also build up the materials it needs for division. Interphase is not a single step. It includes phases such as G1, S, and G2, which help the cell grow, copy DNA, and get...

mitosis and cytokinesis

Cell division depends on mitosis and cytokinesis. Mitosis is the stage when the cell’s nucleus divides and the copied chromosomes are separated into two sets. Cytokinesis is the step that follows and splits the cell into two daughter cells. These two processes work together to make sure each new cell receives genetic material and its own cytoplasm. Mitosis keeps the chromosome sets organized, while cytokinesis finishes the division of the whole cell. Together, they create two separate cells...

the cell cycle control system

Cell Cycle Checkpoints and Cyclin Control

The cell cycle is controlled by checkpoints that help a cell move from one phase to the next and begin mitosis. This control system uses internal regulatory molecules and outside signals to send stop or advance instructions. It makes sure each step is finished before the cell moves forward. Cyclins and cyclin-dependent kinases, or Cdks, are the main regulators of the cell cycle. They act during the G1, G2, and M phases. These regulators work at specific checkpoints to keep cell division...

molecular factors affecting cell division

molecular-factors-affecting-cell-division

Cell Cycle Regulators That Control Division

Cell division is controlled by outside signals and by internal cell cycle regulators. Nearby cell death can encourage division, and human growth hormone (hGH) can also promote it. In contrast, too little hGH or crowded cells can slow or stop division. Inside the cell, regulator molecules help each stage finish correctly before the next stage begins. Some regulators act directly on the cycle, while others affect the activity or production of other regulatory proteins. These molecules can either...

what is meiosis?

Meiosis and the Formation of Gametes

Meiosis is the cell division process that forms gametes, or sex cells. It reduces the chromosome number so offspring can inherit the correct amount of genetic material. This process includes two successive divisions. First, one cell divides, and then the resulting cells divide again. These steps separate the genetic material in a controlled way. Meiosis helps explain how sexual reproduction passes traits from one generation to the next. It is a key topic in high school biology because it...

overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways and responses help cells communicate and react to changes. Cells send signals to one another, and those signals can trigger a specific response in the target cell. A signal usually begins when a signaling molecule reaches a cell with the right receptor, which is a protein that receives the message. The receptor helps the cell recognize the signal and start the communication process. Inside the cell, the message can move through a signaling pathway. This pathway passes...

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g protein-coupled receptors

G Protein-coupled Receptor Signaling

G protein-coupled receptors are a major class of cell-surface receptors. They help cells detect signals outside the cell and pass that information inward. These receptors are important in many kinds of cell communication. When a signal binds to a G protein-coupled receptor, the receptor changes shape. That change activates a G protein inside the cell. The activated G protein can then start a signaling pathway. This signaling system includes the receptor, the G protein, and the downstream...

cellular differentiation

From Stem Cell to Specialized Cells

Cellular differentiation turns unspecialized cells into specialized cells with specific jobs. This process helps a complex organism, such as a human, develop from a single fertilized egg into a body with many cell types. Nerve cells, muscle cells, and epithelial cells are examples of the final cell types that appear during development. A zygote is the first cell after fertilization. It is a totipotent stem cell, which means it has very high differentiation potential and can form all cell types...

key terms and concepts

Learn how mitosis separates copied chromosomes and how cytokinesis divides the cell into two daughter cells in this high school biology page.

Cell Division: Mitosis and Cytokinesis | JoVE K12

anatomy and physiology

O JoVE Core Anatomia e Fisiologia apresenta detalhes anatômicos e fisiológicos do corpo humano em animações  abrangentes, claras e envolventes. Esta coleção de vídeos se concentra nas estruturas, componentes, funções e requisitos do corpo humano. É complementada por vídeos de cientistas em ação que demonstram a aplicação desse conhecimento em instalações médicas e de pesquisa do mundo real.

Cell Division: Mitosis and Cytokinesis

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