Name: cell organelles and microenvironments
Uploaded: 2025-11-18T06:54:45.000Z
Duration: 1 min 46 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

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.1.3

Eukaryotic Compartmentalization

- [Narratore] Le cellule
eucariote contengono

numerosi scomparti interni,

organuli circondati da membrane,

che permettono funzioni molto specifiche

all'interno di microambienti,

protetti sia dall'interno citoplasmatico

che dai dintorni extracellulari.

Ad esempio, il nucleo richiede

condizioni controllate per
una regolazione precisa

dei geni all'interno.

Quindi, è circondato
da una doppia membrana,

la membrana nucleare,

con pori per controllare
quali molecole possono entrare

e uscire, come le MRNA.

Inoltre, alcune proteine
richiedono un ambiente ossidante

e devono essere isolate dal citosol

che è riducente.

Quindi, i ribosomi
producono queste proteine

all'interno del reticolo endoplasmatico

dove possono anche subire
modifiche critiche.

Movimenti successivi si verificano

entro piccoli microcosmi
chimici detti vescicole,

mentre si dirigono alla
destinazione finale.

Altri organuli, come i perossisomi,

forniscono protezione dai
loro prodotti derivati dannosi

come il perossido di idrogeno,

sequestrando enzimi che
convertono composti tossici

in molecole innocue come l'acqua.

In modo simile, i lisosomi
segregano gli enzimi,

ma per un motivo diverso,

per salvaguardare le reazioni digestive

che richiedono un pH
molto più basso di quello

covato dal citoplasma.

Anche i mitocondri hanno un interno acido,

tra le loro due membrane

che aiutano a produrre energia.

Nel complesso, la classificazione
delle cellule eucariote

sostiene azioni che altrimenti

sarebbero incompatibili se
eseguite simultaneamente

senza una forma di contenimento.

Gabaldón, Toni e Alexandros A. Pittis. "Origine ed evoluzione della compartimentazione subcellulare metabolica negli eucarioti". Biochimie 119 (dicembre 2015): 262–68. [<a href="https://doi.org/10.1016/j.biochi.2015.03.021" target="__blank">Sorgente</a>]

compartimentazione eucariotica

Una delle caratteristiche distintive delle cellule eucariotiche è che contengono organelli legati alla membrana, come il nucleo e i mitocondri, che svolgono particolari funzioni. Poiché le membrane biologiche sono permeabili solo a un piccolo numero di sostanze, la membrana intorno a un organello crea un compartimento con condizioni controllate all'interno. Questi microambienti sono spesso distinti dall'ambiente del citosol circostante e sono su misura per le funzioni specifiche dell'organello.

Ad esempio, i lisosomi, gli organelli nelle cellule animali che digeriscono molecole e detriti cellulari, contengono un ambiente più acido del citosol circostante, perché i suoi enzimi richiedono un pH inferiore per catalizzare le reazioni. Allo stesso modo, il pH è regolato all'interno dei mitocondri, che li aiuta a svolgere la loro funzione di produrre energia.

Inoltre, alcune proteine richiedono un ambiente ossidativo per una corretta ripiegatura e processamento, ma il citosol è generalmente riduttivo. Pertanto, queste proteine sono prodotte da ribosomi nel reticolo endoplasmico (ER), che mantiene l'ambiente necessario. Le proteine vengono spesso trasportate all'interno della cellula attraverso vesciche legate alla membrana.

Il materiale genetico delle cellule eucariotiche è compartimentato all'interno del nucleo, che è circondato da una doppia membrana chiamata involucro nucleare. Piccoli pori nella busta controllano quali molecole o ioni possono entrare o uscire dal nucleo. Per esempio, l'RNA messaggero (mRNA) esce dal nucleo attraverso questi pori per portare le istruzioni genetiche codificate nel DNA ai ribosomi, dove possono essere tradotte in proteine.

Gli Organelli possono anche proteggere una cellula contenendo e neutralizzando sostanze pericolose. Ad esempio, i perossisomi eseguono reazioni di ossidazione che producono perossido di idrogeno, che è tossico per le cellule, ma contengono anche enzimi che lo convertono in ossigeno e acqua innocui. Pertanto, la compartimentazione consente alle cellule eucariotiche di svolgere una varietà di funzioni diverse che altrimenti sarebbero incompatibili in termini di ambienti richiesti o sottoprodotti prodotti.

Compartimentazione eucariotica

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Education

Didattica

JoVE Core

Biologia

Cellular Processes

Processi cellulari

Cell Structure and Function

Struttura e funzione della cellula

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

cell organelles and microenvironments

Eukaryotic cells use membrane-bound organelles to keep cell processes organized. The nucleus and mitochondria are two key examples. Because biological membranes are selectively permeable, they create controlled spaces inside each organelle. These small microenvironments support specialized jobs and separate them from the surrounding cytosol.

Different organelles maintain different internal conditions. In animal cells, lysosomes keep an acidic environment that helps their enzymes digest cellular debris. Mitochondria also regulate pH, which supports the synthesis of energy molecules. These conditions show how compartmentalization helps each organelle work efficiently.

Some proteins need an oxidative environment to fold and be processed correctly. The cytosol is usually reductive, so these proteins are made by ribosomes in the endoplasmic reticulum, or ER. The ER provides the needed environment, and vesicles move the proteins to their final destination. This transport system helps direct proteins to the right place in the cell.

The nucleus also depends on compartmentalization. It holds the cell’s genetic material inside a double membrane called the nuclear envelope. Small pores in the envelope control what enters and leaves the nucleus. Messenger RNA, or mRNA, exits through these pores and carries DNA instructions to ribosomes for protein synthesis. Overall, compartmentalization lets one cell carry out many functions with greater efficiency by concentrating needed materials in separate spaces.

Cell Organelles and Microenvironments

what are cells?

Cell Membrane, DNA, and Organelles

Cells are the basic units of life, from a bacterium made of one cell to a human made of trillions. Even though organisms can differ greatly, their cells share key features that support life. A cell has a plasma membrane, which is a lipid bilayer that separates the cytoplasm from the outside environment. It also contains DNA, the genetic material that carries instructions for the cell. In prokaryotic cells, DNA is found in a region called the nucleoid. In eukaryotic cells, DNA is enclosed...

cell size

Why Cell Size Is Limited

Cell size is limited by surface area and diffusion. Cells vary widely in size, both between organisms and within the same organism. Bacterial cells are usually 1 to 10 micrometers wide, and the smallest bacteria can be 0.1 micrometers in diameter. That is about a thousand times smaller than most eukaryotic cells, which are typically 10 to 100 micrometers across. A cell takes in nutrients and water through diffusion across the plasma membrane or through channels in the membrane. The membrane...

eukaryotic compartmentalization

Eukaryotic cells use membrane-bound organelles to keep cell processes organized. The nucleus and mitochondria are two key examples. Because biological membranes are selectively permeable, they create controlled spaces inside each organelle. These small microenvironments support specialized jobs and separate them from the surrounding cytosol. Different organelles maintain different internal conditions. In animal cells, lysosomes keep an acidic environment that helps their enzymes digest...

prokaryotic cells

Prokaryotic Cell Structures

Prokaryotic cells are small, single-celled organisms found in the domains Archaea and Bacteria. Bacteria include familiar species such as Salmonella and E. coli. Archaea include extremophiles, which are organisms that live in harsh environments like volcanic springs. Prokaryotic cells share several basic features with eukaryotic cells. They are surrounded by a plasma membrane, contain cytoplasm, and have ribosomes that make proteins. Their genetic material is a single, circular DNA molecule.

cytoplasm

Cytoplasm and the Cell’s Internal Framework

The cytoplasm is the cell’s internal space that holds organelles and the cytoskeleton. It is suspended in the cytosol, an aqueous fluid made of water, ions, salts, and many organic molecules. Together, these parts create the environment where key cell activities happen. The cytoplasm is also a major site for protein synthesis and folding. The water-based cytosol helps proteins fold correctly. Hydrophobic amino acid side chains tend to hide in the protein core, while hydrophilic amino acids...

endoplasmic reticulum

ER in Protein and Lipid Transport

The endoplasmic reticulum is a membrane network in eukaryotic cells. It is continuous with the outer membrane of the nucleus. This connection helps link nuclear and cytoplasmic processes and supports efficient movement inside the cell. mRNA can move from the nucleus to ribosomes, which helps protein synthesis happen efficiently. The ER is a major site for making, processing, and distributing biomolecules. The rough endoplasmic reticulum has ribosomes attached to its surface. These ribosomes...

ribosomes

How Ribosomes Build Proteins

Ribosomes build proteins by reading messenger RNA, or mRNA, and linking amino acids in the right order. Both prokaryotic and eukaryotic cells contain ribosomes. Cells that make large amounts of protein, such as secretory cells in the human pancreas, can have millions of them. Ribosomes are made of ribosomal RNA, or rRNA, and proteins. In eukaryotic cells, rRNA is transcribed from genes in the nucleolus, a part of the nucleus that specializes in making ribosomes. There, rRNA combines with...

golgi apparatus

Protein Sorting in the Golgi Apparatus

The Golgi apparatus sorts and modifies proteins after they leave the endoplasmic reticulum (ER). Properly folded and assembled proteins are packaged into vesicles, or small membrane sacs, and moved by microtubule-based motor proteins. These vesicles can fuse into vesicular tubular clusters before reaching the Golgi, which often looks like a ribbon-shaped organelle in eukaryotic cells. Vesicles enter the cis face of the Golgi, the side facing the ER. They pass through a set of pancake-shaped...

peroxisomes

Peroxisomes and Cellular Detoxification

Peroxisomes and mitochondria are two important oxygen-utilizing organelles in eukaryotic cells. Mitochondria carry out cellular respiration, which turns energy from food into ATP. Peroxisomes focus on breaking down substances such as fatty acids and other materials the cell needs to process. A peroxisome is a single membrane-bound organelle. It helps with lipid metabolism and chemical detoxification. Enzymes inside peroxisomes move hydrogen atoms from molecules to oxygen. This reaction...

microtubules

Microtubules in Cells and Cell Movement

Microtubules are cytoskeletal fibers that help cells keep their shape, move materials, and divide. They are the thickest of the three main cytoskeletal structures in eukaryotic cells, with a diameter of about 25 nm. Along with microfilaments and intermediate filaments, they form the internal support network of the cell. Microtubules are hollow tubes built from tubulin proteins. Each tubulin molecule is a heterodimer, which means it has two different parts: α-tubulin and β-tubulin. These dimers...

plant cell wall

Plant Cell Walls in Growth and Support

Plant cell walls help plant cells keep their shape, stay protected, and remain supported. As a cell matures, its wall can change based on the cell type. Parenchyma cells in leaves usually have only a thin primary cell wall. These walls are part of how different plant cells take on different jobs. Collenchyma and sclerenchyma cells are found mostly in the outer layers of stems and leaves. Collenchyma cells add strength by partially thickening the primary cell wall. Sclerenchyma cells provide...

plasmodesmata

Plasmodesmata and Plant Cell Communication

Plasmodesmata are the connections that let plant cells communicate directly. These tiny passageways link neighboring cells through the cell wall and help tissues work together in a multicellular plant. Cells in multicellular organisms must communicate to function as a unit. One way they do this is through intercellular junctions, which are contact points between adjacent cells. Fungal, plant, and animal cells all have intercellular junctions, but the types differ. In animal cells, the main...

the nucleus

Nuclear DNA and Cell Control

The nucleus is the control center of a eukaryotic cell. It is a membrane-bound organelle that contains chromosomal DNA. That DNA helps control gene expression and regulate protein production in the cell. Not all cellular DNA has the same role. The DNA in mitochondria and chloroplasts supports functions that are specific to those organelles. Inside the nucleus, DNA structure also affects how genes are regulated. Nuclear DNA is wrapped around proteins called histones. This forms chromatin, a...

the extracellular matrix

How ECM Supports Animal Tissues

The extracellular matrix (ECM) supports animal tissues by surrounding cells with structural molecules. It helps maintain tissue organization and gives tissues their specific physical properties. The ECM includes a gel-like ground substance, fibrous components, and many molecules with different jobs. A major part of the ECM is made of glycosaminoglycans, or GAGs. These polysaccharides fill much of the extracellular space and can take up a large volume for their mass. That makes the matrix...

gap junctions

Connexins and Cell-to-Cell Signaling

Gap junctions help animal cells send signals and share small materials with nearby cells. They are made of special proteins that form pores between neighboring cells and connect their cytoplasm. Through these channels, cells can exchange ions and other small molecules. These communication channels are found in many invertebrate and vertebrate species. They support important processes such as cell differentiation and development. They are also linked to human diseases, including disorders of...

tissues

Body Tissues and Their Jobs

Body tissues are groups of cells with similar structure and function. When different tissues work together, they form an organ with a specialized job. Vertebrates have four main tissue types: epithelial, connective, muscle, and nervous tissue. Epithelial tissue is made of thin sheets of cells. It covers the skin and lines internal organs and body cavities. These cells are tightly packed, so they help protect against injury, infection, and water loss. Epithelial tissue may be simple, with one...

key terms and concepts

Learn how membrane-bound organelles create controlled microenvironments in eukaryotic cells, from acidic lysosomes to the nucleus and mRNA export.

Cell Organelles and Microenvironments | JoVE K12

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Pennsylvania State Academic Standards

Life Science

Structure and Function

3.1.9-12.A

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Ohio’s Learning Standards and Model Curriculum

Cells

Cell structure and function

Virginia  Standards of Learning

HIgh School

BIO.3

BIO.3.a

Arizona Science Standards

High School

HS+B.L1

HS+B.L1U1.4

Alabama Course of Study Science

From Molecules to Organisms: Structures and Processes

9-12.B.1.1

Florida Department of Education

SC.912.L.14

SC.912.L.14.2

SC.912.L.14.3

SC.912.L.14.5

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LS.Bio.1.2

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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 ...

Endoplasmic Reticulum

Endoplasmic ReticulumThe endoplasmic reticulum (ER) is an extensive network of membranous sacs and tubules in eukaryotic cells, continuous with the outer ...

Ribosomes

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Golgi Apparatus

As they leave the Endoplasmic Reticulum (ER), properly folded and assembled proteins are selectively packaged into vesicles. These vesicles are ...

Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules ...

Peroxisomes

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Introduction to the Cytoskeleton

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Background
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Gap Junctions

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Use models to explain how the structure of organelles determines its function and supports overall cell processes.

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

Cell Organelles and Microenvironments

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