Cellular Structure and Function

Cell

Basic unit of life

Plasma (cell) membrane

A selectively-permeable phospholipid bilayer

Eukaryotic cell

A cell with a membrane-enclosed nucleus and membrane-enclosed organelles; protists, plants, fungi, and animals

Prokaryotic cell

A cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; bacteria

Nucleus

Organelle in the cell that contains DNA; controls cell processes

Selectively premeability

The cell membrane controls what can cross it, so that only certain molecules either enter or leave the cell

Cytoplasm

A jellylike fluid inside the cell

Nucleolus

Structure inside the nucleus where the assembly of ribosomes begins

Ribosome

Organelle that makes proteins

Endoplasmic reticulum

An internal membrane system in which parts of the cell membrane and some proteins are constructed

Golgi apparatus

Modifies, sorts, and packages proteins into vesicles and transports them to other organelles or out of the cell

Vacuole

Stores materials such as water, salts, proteins, and carbohydrates

Centriole

Structures that help with cell division

Lysosome

Organelle that contains digestive enzymes that break down things in cells

Chloroplast

Organelle where photosynthesis occurs

Mitochondria

Powerhouse of the cell

Cell wall

Strong, supporting layer around the cell membrane in some cells

Cilia

Hairlike projections that extend from the plasma membrane; used for locomotion

Flagella

A long, whiplike structure protruding from a cell; used for locomotion

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration

Facilitated diffusion

The transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins

Osmosis

Diffusion of water through a selectively permeable membrane

Hypotonic solution

Solute concentration in less than that inside the cell; cell gains water

Hypertonic solution

Solute concentration is greater than that inside the cell; cell loses water

Isotonic solution

A solution with the same concentration of water and solutes as inside a cell; cell retaining its normal shape

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Endocytosis

A process in which a cell engulfs material through an inward folding of its plasma membrane

Exocytosis

Process by which a cell releases large amounts of material