CELLS

Cell

The basic structural and functional unit of living organisms.

Cell theory

The set of principles stating that all living things are made of cells, cells arise from pre-existing cells, and the cell is the basic unit of life.

Unicellular organism

An organism made up of only one cell (e.g., Euglena, Paramecium, yeast)

Multicellular organism

An organism made up of more than one cell (e.g., plants, animals, fungi).

Ultrastructure

The structure of a cell as seen under an electron microscope

Plasma membrane

The thin, elastic, semi-permeable membrane enclosing the cell; regulates what enters and exits

Cell wall

The rigid, non-living outer covering of plant and bacterial cells, made of cellulose, hemicellulose, and pectin

The dense, membrane-bound structure that houses the cell's genetic material and controls cell activities.

Nucleus

Nuclear envelope

The double-layered membrane surrounding the nucleus, containing nuclear pores.

Nucleoplasm

The dense fluid inside the nucleus.

Nucleolus

A structure within the nucleus that synthesizes RNA to build ribosomes.

Chromatin

The network of DNA and histone protein fibers in the nucleus; condenses into chromosomes during division.

Chromosome

A condensed structure of DNA and protein that carries genes.

Gene

A stretch of DNA that carries hereditary information.

Cytoplasm

The jelly-like substance filling the cell between the plasma membrane and the nucleus, containing the cytosol and organelles

Cytosol

The fluid portion of the cytoplasm.

Endoplasmic reticulum (ER)

A network of membranes involved in protein synthesis (rough ER) and lipid synthesis/detoxification (smooth ER).

Golgi body

The organelle that modifies, sorts, and packages materials for delivery within or outside the cell.

Lysosome

A membrane-bound sac of hydrolytic enzymes that digests molecules and destroys foreign invaders.

Vacuole

A fluid-filled sac that stores substances and helps maintain osmotic pressure and turgidity.

Cristae

The folds of the mitochondria's inner membrane that increase surface area for ATP production

Plastid

A double-membrane organelle in plant cells responsible for making/storing food or pigments.

Chromoplast

A plastid that produces and stores pigments, giving color to plant structures.

Leucoplast

A colorless plastid that stores food such as starch, protein, or oil.

Chloroplast

The plastid containing chlorophyll that carries out photosynthesis

Centrosome

An organelle near the nucleus containing centrioles; organizes spindle fibers during cell division.

Centriole

A cylindrical structure made of microtubules, found in pairs within the centrosome.

Cytoskeleton

The internal network of microtubules and microfilaments that gives the cell shape, strength, and the ability to move

Prokaryotic cell

A cell without a true, membrane-bound nucleus or membrane-bound organelles (e.g., bacteria).

Eukaryotic cell

A cell with a well-developed, membrane-bound nucleus and membrane-bound organelles