Cell Structure

Cell

The basic unit of structure and function in an organism.

Cell theory

A scientific theory that states all living things are composed of one or more cells, cells are the basic units of structure and function in an organism, and cells come only from the reproduction of existing cells.

Cell (plasma) membrane

Regulates what goes in and out of a cell.

Cytoplasm

The region of the cell that is within the plasma membrane and includes the fluid, the cytoskeleton, and all of the organelles, except the nucleus.

Cytosol

The fluid component of the cytoplasm.

Nucleus

Contains DNA and makes RNA.

Prokaryote

A type of cell that does not have a nucleus or membrane-bound organelles.

Eukaryote

A type of cell that has a membrane-bound nucleus and membrane-bound organelles.

Organelle

Specialized structures within a cell that perform distinct processes.

Tissue

A group of cells that work together to perform a specific function.

Organ

A structure composed of different types of tissues that work together to perform a specific function.

Organ system

A group of organs that work together to perform complex functions.

Phospholipid bilayer

A double layer of phospholipids that makes up the cell membrane.

Chromosome

A structure made of DNA and proteins that contains genetic information.

Nuclear envelope

The double membrane that surrounds the nucleus.

Nucleolus

The structure within the nucleus that makes ribosomes.

Ribosome

Synthesizes (creates) proteins.

Mitochondrion

Produces ATP (energy) by turning glucose into ATP; site of cellular respiration.

Rough ER

Endoplasmic reticulum with ribosomes attached that modifies, folds, and checks proteins.

Golgi apparatus

Packages cellular products; also known as Golgi body and Golgi complex.

Lysosomes

Breaks down and destroys molecules that enter the cell.

Cytoskeleton

Comprises the cellular framework and helps the cell to divide when it reproduces.

Microtubule

A component of the cytoskeleton that helps maintain cell shape and structure.

Microfilament

A component of the cytoskeleton that helps with cell movement and division.

Cilia (cillium)

Hair-like structures that cause cellular movement.

Flagella (flagellum)

Tail-like structures that cause cellular movement.

Centriole

A structure involved in cell division.

Cell wall

Supports and protects cells; found in plant, fungi, bacteria, and some protist cells.

Plastid

Makes and stores food and cell pigments; an example is chloroplast.

Central vacuole

Stores enzymes and waste products; large in plant cells and small in animal cells.

Chlorophyll

A pigment that absorbs sunlight for photosynthesis.

Chloroplast

An organelle that takes sunlight and CO2 to make glucose through photosynthesis.

Thylakoids

Membrane-bound compartments inside chloroplasts where photosynthesis occurs.

Smooth ER

Endoplasmic reticulum without ribosomes that synthesizes lipids.