Cell Transport

Passive Transport

Movement of substances across the membrane without energy, going from high to low concentration

Active Transport

Movement of substances across the membrane using ATP energy, going from low to high concentration

Concentration Gradient

The difference in concentration between two areas (molecules move from high → low naturally)

Simple Diffusion

Passive transport where small, nonpolar molecules move directly through the membrane (no proteins)

Facilitated Diffusion

Passive transport where molecules move through protein channels or carriers from high → low

Transport Proteins

Proteins in the membrane that help substances move across (used in facilitated diffusion and active transport)

Channel Protein

A protein that forms a tunnel for molecules or ions to pass through

Carrier Protein

A protein that changes shape to move molecules across the membrane

Active Transport Pump

A membrane protein that uses ATP to move substances against the gradient

ATP (Adenosine Triphosphate)

The energy source used by cells to power active transport

Low to High Movement

Movement against the concentration gradient (requires energy)

High to Low Movement

Movement with the concentration gradient (no energy needed)

Endocytosis

Process where the cell takes in large materials by forming a vesicle

Exocytosis

Process where the cell releases materials by vesicles fusing with the membrane

Vesicle

A small membrane-bound sac used to transport materials in bulk transport

Bulk Transport

Movement of large materials into or out of the cell using vesicles (endocytosis & exocytosis)

Phagocytosis

A type of endocytosis where the cell engulfs large particles like bacteria

Receptor-Mediated Endocytosis

Endocytosis that uses specific receptor proteins to take in certain molecules