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

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From Molecules to Organisms- Structures and Processes

LS.Bio.1.4

Prokaryotic Cells

I procarioti includono archei e batteri, semplici organismi unicellulari privi di organelli legati alla membrana.
Questi organismi sono circondati da una membrana plasmatica selettivamente permeabile che racchiude componenti cellulari, liberamente sospesi nel citoplasma viscoso.
Oltre alla membrana plasmatica, le cellule batteriche hanno un ulteriore livello di protezione sotto forma di una parete cellulare che aiuta a mantenere la loro forma complessiva e la pressione osmotica interna.
La parete cellulare è costituita da peptidoglicano, un polimero di amminoacidi e zuccheri.
Alcuni batteri hanno un altro strato di difesa chiamato capsula, uno strato di polisaccaridi che promuove l'adesione delle cellule alle superfici.
All'interno della cellula, un singolo DNA a doppio filamento è raggruppato in una regione centrale chiamata nucleoide, dove può interagire con le proteine che fluttuano liberamente.
La maggior parte dei batteri ha anche pezzi circolari di DNA che fluttuano liberamente, chiamati plasmidi, che possono replicarsi in modo indipendente e conferire vantaggi di sopravvivenza come la resistenza agli antibiotici.
Alcune specie batteriche possono contenere proteine specifiche e organelli legati ai lipidi con funzioni distinte.
Ad esempio, i cianobatteri possiedono carbossisomi e tilacoidi per raccogliere l'energia luminosa per effettuare la fotosintesi.

cellule procariotiche

I procarioti sono piccoli organismi unicellulari che includono i domini: Archaea e Batteri. I batteri includono molti microrganismi comuni, come Salmonella ed E. coli, mentre gli Archaea includono estremofili che vivono in ambienti difficili, come le sorgenti vulcaniche.

Come le cellule eucariotiche, tutte le cellule procariotiche sono circondate da una membrana plasmatica, hanno materiale genetico sotto forma di DNA singolo e circolare, un citoplasma che riempie l'interno della cellula e ribosomi che sintetizzano le proteine. Tuttavia, a differenza delle cellule eucariotiche, i procarioti sono privi di nucleo o di altri organelli intracellulari legati alla membrana. I loro componenti cellulari fluttuano liberamente nel citoplasma, sebbene il loro DNA sia raggruppato in una regione chiamata nucleoide.

All'interno del citoplasma, molti procarioti hanno piccoli pezzi circolari di DNA a doppio filamento chiamati plasmidi. Questi sono distinti dal DNA cromosomico della cellula e portano solo pochi geni speciali che forniscono ai batteri vantaggi in termini di sopravvivenza, come la resistenza agli antibiotici. I plasmidi si autoreplicano e possono essere trasmessi tra cellule procariotiche.

La maggior parte dei batteri ha una parete cellulare composta da peptidoglicano che si trova all'esterno della membrana plasmatica. Protegge fisicamente la cellula e la aiuta a mantenere la pressione osmotica in diversi ambienti. Molti batteri hanno anche uno strato di capsula appiccicosa che ricopre la parete cellulare e consente loro di aderire a un substrato o tra loro, fornendo così una protezione aggiuntiva.

Sebbene i batteri non abbiano organelli legati alla membrana, alcuni hanno ripiegamenti della membrana plasmatica che svolgono funzioni specializzate, come la fotosintesi nei cianobatteri. Pertanto, sebbene i procarioti siano cellule semplici rispetto agli eucarioti, possiedono alcune strutture uniche che li aiutano a svolgere funzioni complesse e consentono loro di vivere in un'ampia varietà di ambienti.

Cellule procariotiche

I procarioti sono piccoli organismi unicellulari che includono i domini Archaea e Bacteria. I batteri includono molti microrganismi comuni, come ...

Education

Didattica

JoVE Core

Cell Biology

Biologia cellulare

Unit 1

Unità 1

Cells, Genomes, and Evolution

Cellule, genomi ed evoluzione

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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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prokaryotic cells

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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 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

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Heredity: Inheritance And Variation Of Traits

HS-LS3-1

Tennessee Academic Standards

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BIO.3

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BIO.6

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LS.3

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Florida Department of Education

SC.912.L.15

SC.912.L.15.6

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How Prokaryotes Survive Without a Nucleus

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