Name: how prokaryotes survive without a nucleus
Uploaded: 2023-04-30T10:29:03.000Z
Duration: 1 min 28 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

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

From Molecules to Organisms- Structures and Processes

LS.Bio.1.4

Prokaryotic Cells

Os procariontes incluem archaea e bactérias, organismos unicelulares simples que não possuem organelas ligadas à membrana.
Esses organismos são cercados por uma membrana plasmática seletivamente permeável que envolve componentes celulares, livremente suspensos no citoplasma viscoso.
Além da membrana plasmática, as células bacterianas têm um nível extra de proteção na forma de uma parede celular que ajuda a manter sua forma geral e pressão osmótica interna.
A parede celular é composta de peptidoglicano – um polímero de aminoácidos e açúcares.
Algumas bactérias têm outra camada de defesa chamada cápsula – uma camada de polissacarídeo que promove a adesão celular às superfícies.
Dentro da célula, um único DNA de fita dupla é agrupado em uma região central chamada nucleóide, onde pode interagir com proteínas que flutuam livremente.
A maioria das bactérias também tem pedaços circulares de DNA flutuando livremente, chamados plasmídeos, que podem se replicar independentemente e conferir vantagens de sobrevivência, como resistência a antibióticos.
Algumas espécies bacterianas podem conter proteínas específicas e organelas ligadas a lipídios com funções distintas.
Por exemplo, as cianobactérias possuem carboxissomas e tilacóides para coletar energia luminosa para realizar a fotossíntese.

células procarióticas

Os procariontes são pequenos organismos unicelulares que incluem os domínios – Archaea e Bacteria. As bactérias incluem muitos microrganismos comuns, como Salmonella e E. coli, enquanto as Archaea incluem extremófilos que vivem em ambientes adversos, como fontes vulcânicas. Assim como as células eucarióticas, todas as células procarióticas são cercadas por uma membrana plasmática, possuem material genético na forma de DNA circular único, um citoplasma que preenche o interior da célula e ribossomos que sintetizam proteínas. No entanto, ao contrário das células eucarióticas, os procariontes não possuem núcleo ou outras organelas intracelulares ligadas à membrana. Seus componentes celulares flutuam livremente dentro do citoplasma, embora seu DNA esteja agrupado em uma região chamada nucleóide. Dentro do citoplasma, muitos procariontes possuem pequenos pedaços circulares de DNA de fita dupla chamados plasmídeos. Eles são distintos do DNA cromossômico da célula e carregam apenas alguns genes especiais que proporcionam às bactérias vantagens de sobrevivência, como resistência a antibióticos. Os plasmídeos são auto-replicantes e podem ser transmitidos entre células procarióticas. A maioria das bactérias tem uma parede celular feita de peptidoglicano que fica fora da membrana plasmática. Ela protege fisicamente a célula e ajuda a manter a pressão osmótica em diferentes ambientes. Muitas bactérias também possuem uma camada de cápsula pegajosa que cobre a parede celular e permite que se grudem em um substrato ou entre si, proporcionando proteção adicional. Embora as bactérias não possuam organelas ligadas à membrana, algumas possuem dobras da membrana plasmática que realizam funções especializadas – como a fotossíntese em cianobactérias. Portanto, embora os procariontes sejam células simples em comparação com os eucariontes, eles possuem algumas estruturas únicas que os ajudam a realizar funções complexas e lhes permitem viver em uma ampla variedade de ambientes.

Células Procarióticas

Os procariontes são pequenos organismos unicelulares que incluem os domínios - Archaea e Bacteria. As bactérias incluem muitos microrganismos comuns, como ...

Education

JoVE Core

Cell Biology

Biologia Celular

Unit 1

Unidade 1

Cells, Genomes, and Evolution

Células, Genomas e Evolução

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

how prokaryotes survive without a nucleus

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs.

Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the cytoplasm because they do not have membrane-bound intracellular organelles.

Their DNA is clustered in a region called the nucleoid. Many prokaryotes also carry plasmids, which are small, circular, double-stranded DNA molecules. Plasmids are separate from chromosomal DNA and can carry genes that give survival advantages, such as antibiotic resistance. They can also self-replicate and move between prokaryotic cells.

Most bacteria have a cell wall made of peptidoglycan outside the plasma membrane. This wall helps protect the cell and supports osmotic pressure in different environments. Many bacteria also have a sticky capsule that covers the wall and helps them attach to surfaces or to other cells. Some bacteria even have infoldings of the plasma membrane for special jobs, such as photosynthesis in cyanobacteria.

How Prokaryotes Survive Without a Nucleus

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Cells are the basic building blocks of life. A bacterium can be a single cell, while a human is made of trillions of cells. Even with this range, cells share key features that support life. A living cell has a plasma membrane. This is a bilayer of lipids that separates the cytoplasm inside the cell from the outside environment. A cell also carries genetic information in the form of DNA. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

the tree of life - bacteria, archaea, and eukaryotes

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Three Domains on the Tree of Life

The tree of life shows how living things are grouped into three domains: Bacteria, Archaea, and Eukaryotes. This classification helps explain the major branches of life and how they are related. Bacteria and Archaea are both single-celled organisms, but they are not the same. Eukaryotes include organisms with more complex cells, such as plants, animals, and fungi. Together, these three domains give a broad picture of life on Earth. Understanding the tree of life helps students compare cell...

prokaryotic cells

Prokaryotes are small unicellular organisms that live without a nucleus. They include the domains Archaea and Bacteria. Bacteria include common microbes such as Salmonella and E. coli, while Archaea include extremophiles that live in harsh places like volcanic springs. Prokaryotic cells still share several basic features with eukaryotic cells. They have a plasma membrane, cytoplasm, ribosomes, and genetic material in the form of single, circular DNA. Their cell parts float freely in the...

eukaryotic compartmentalization

How Organelles Keep Cells Working

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eukaryotic evolution

How Eukaryotic Cells Became Complex

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cytoplasm

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the nucleus

Nuclear DNA, Chromatin, and Nucleoli

The nucleus is a membrane-bound organelle that stores chromosomal DNA and helps control what proteins a eukaryotic cell makes. It acts as the cell’s control center. DNA in mitochondria and chloroplasts is different because it mainly supports functions specific to those organelles. Inside the nucleus, DNA is wrapped around proteins called histones. This DNA-protein complex is called chromatin. During interphase, when the cell is not dividing, chromatin stays loosely arranged so the DNA is easy...

the dna helix

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the central dogma

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DNA to protein flow depends on RNA as the link between genetic information and the amino acids that build proteins. Early scientists knew that DNA stores the information for cell functions and that proteins carry out most of those functions. For a long time, they did not know how the code in DNA became a working protein. At first, many people thought one gene was changed directly into its protein. Two findings in eukaryotic cells challenged that idea. Protein production does not happen in the...

mutations

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Genome Size and Gene Evolution

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Gene Evolution Rates and Selection

Gene evolution can happen at different rates, and natural selection helps shape those changes. Some genes change slowly because important DNA changes are removed over time. Other genes can change more quickly when different mutations are kept in a population. The rate of evolution depends on how a gene is used and how strongly it is affected by selection. Genes with essential jobs often stay more similar across species. Genes under weaker pressure may show more variation and may evolve faster.<br...

types of genetic transfer between organisms

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Vertical and Horizontal Gene Transfer

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key terms and concepts

Learn how prokaryotes survive without a nucleus, from circular DNA and plasmids to peptidoglycan cell walls, capsules, and specialized membrane folds.

How Prokaryotes Survive Without a Nucleus | JoVE K12

cell biology

JoVE Core - Biologia Celular ilustra processos celulares complexos em vídeos de animação fáceis de entender e, ao mesmo tempo, abrangentes. Esta coleção foca nos componentes e funções essenciais das células, incluindo organelas e membranas, transporte celular e energia celular. É complementado por vídeos de Cientistas em ação que demonstram a aplicação da biologia celular em experimentos de pesquisa do mundo real.

Louisiana Student Standards for Science

High School

Life Sciences

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Heredity: Inheritance And Variation Of Traits

HS-LS3-1

Tennessee Academic Standards

From Molecules to Organisms: Structures and Processes

BIO1.LS1.1

BIO1.LS1.2

Virginia  Standards of Learning

HIgh School

BIO.3

BIO.3.b

BIO.6

BIO.6.a

Life Science

LS.3

LS.3.b

Florida Department of Education

SC.912.L.15

SC.912.L.15.6

Georgia Standards of Excellence

SB4.a

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Cytoplasm

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The Nucleus

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Endoplasmic Reticulum

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Ribosomes

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Golgi Apparatus

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Lysosomes

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LS.Bio.1.3

Analyze how the relationship between structure and function supports life processes within organisms.

How Prokaryotes Survive Without a Nucleus

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