ORGANELLES

Cell Membrane

A fluid mosaic bilayer composed of lipids and proteins that surrounds the cytoplasm of an animal cell and lies internal to the cell wall of a plant cell. It regulates the passage of materials into and out of the cell.

Cytoplasm

The entire contents within the cell membrane (excluding the nucleus in eukaryotic cells), consisting of the cytosol (the gel-like substance) and the organelles suspended within it. It's the site of many metabolic reactions.

Nucleus

A membrane-bound organelle (in eukaryotic cells) that houses the cell's genetic material (DNA) organized into chromosomes. It controls cell growth, metabolism, and reproduction.

Mitochondria

Often called the "powerhouses" of the cell, these double-membraned organelles are responsible for cellular respiration, generating most of the cell's supply of ATP (adenosine triphosphate) for energy.

Ribosomes

Small complexes composed of ribosomal RNA (rRNA) and proteins, found free in the cytoplasm or bound to the endoplasmic reticulum. They are the primary sites of protein synthesis (translation).

Endoplasmic Reticulum (ER)

A vast network of membranes that extends throughout the cytoplasm. It serves as a manufacturing and packaging system for proteins and lipids.

Rough Endoplasmic Reticulum (RER)

A portion of the ER studded with ribosomes, involved in the synthesis, folding, modification, and transport of proteins that are destined for secretion, insertion into membranes, or delivery to other organelles.

Smooth Endoplasmic Reticulum (SER)

A portion of the ER lacking ribosomes, involved in lipid synthesis (including hormones), detoxification of drugs and poisons, and storage of calcium ions.

Golgi Apparatus (Golgi Complex/Body)

A series of flattened membrane-bound sacs (cisternae) that modifies, sorts, and packages proteins and lipids synthesized in the ER for secretion or delivery to other organelles.

Lysosomes

Membrane-bound organelles (more common in animal cells) containing a variety of hydrolytic enzymes that break down waste materials and cellular debris, as well as worn-out organelles and foreign invaders.

Peroxisomes

Small, single-membraned organelles that perform various metabolic functions, including breaking down fatty acids and detoxifying harmful substances, often producing hydrogen peroxide as a byproduct.

Centrioles (Animal Cells Only)

Paired barrel-shaped organelles found in the cytoplasm of animal cells, involved in cell division by organizing the mitotic spindle and also forming the base of cilia and flagella.

Cell Wall (Plant Cells Only)

A rigid, protective outer layer found in plant (and fungal, algal, bacterial) cells, external to the cell membrane. It provides structural support, protection, and prevents excessive water uptake.

Chloroplasts (Plant Cells Only)

Plastids containing the green pigment chlorophyll, found in plant and algal cells. They are the sites where photosynthesis takes place, converting light energy into chemical energy in the form of glucose.

Large Central Vacuole (Plant Cells Only)

A large, membrane-bound sac that occupies much of the volume of mature plant cells. It stores water, nutrients, waste products, and maintains turgor pressure against the cell wall, providing structural rigidity.

Ribosomes

Small complexes composed of ribosomal RNA (rRNA) and proteins, found free in the cytoplasm or bound to the endoplasmic reticulum. They are the primary sites of protein synthesis (translation).

Endoplasmic Reticulum (ER)

A vast network of membranes that extends throughout the cytoplasm. It serves as a manufacturing and packaging system for proteins and lipids.

Rough Endoplasmic Reticulum (RER)

A portion of the ER studded with ribosomes, involved in the synthesis, folding, modification, and transport of proteins that are destined for secretion, insertion into membranes, or delivery to other organelles.

Smooth Endoplasmic Reticulum (SER)

A portion of the ER lacking ribosomes, involved in lipid synthesis (including hormones), detoxification of drugs and poisons, and storage of calcium ions.

Golgi Apparatus (Golgi Complex/Body)

A series of flattened membrane-bound sacs (cisternae) that modifies, sorts, and packages proteins and lipids synthesized in the ER for secretion or delivery to other organelles.

Lysosomes

Membrane-bound organelles (more common in animal cells) containing a variety of hydrolytic enzymes that break down waste materials and cellular debris, as well as worn-out organelles and foreign invaders.

Peroxisomes

Small, single-membraned organelles that perform various metabolic functions, including breaking down fatty acids and detoxifying harmful substances, often producing hydrogen peroxide as a byproduct.

Centrioles (Animal Cells Only)

Paired barrel-shaped organelles found in the cytoplasm of animal cells, involved in cell division by organizing the mitotic spindle and also forming the base of cilia and flagella.

Cell Wall (Plant Cells Only)

A rigid, protective outer layer found in plant (and fungal, algal, bacterial) cells, external to the cell membrane. It provides structural support, protection, and prevents excessive water uptake.

Chloroplasts (Plant Cells Only)

Plastids containing the green pigment chlorophyll, found in plant and algal cells. They are the sites where photosynthesis takes place, converting light energy into chemical energy in the form of glucose.

Large Central Vacuole (Plant Cells Only)

A large, membrane-bound sac that occupies much of the volume of mature plant cells. It stores water, nutrients, waste products, and maintains turgor pressure against the cell wall, providing structural rigidity.

Nucleolus

A dense structure within the nucleus of eukaryotic cells, primarily involved in the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes.