Homeostasis and Cell Transport Vocabulary Review Homeostasis and Cell Transport

The movement of substances across a cell membrane without any input of energy Passive Transport

The movement of molecules from an area of higher concentration to an area of lower concentration Diffusion

The difference in the concentration of molecules across a distance Concentration gradient

Concentration of molecules is the same throughout the space the molecules occupy Equilibrium

Movement of water molecules from high concentration to low concentration Osmosis

Concentration of solute molecules outside the cell is LOWER than in the cytosol; water diffuses into the cell Hypotonic

Concentration of solute molecules outside the cell is HIGHER than in the cytosol; water diffuses out of the cell Hypertonic

Concentrations of solutes outside and inside the cell are equal Isotonic

Organelles that remove water through contraction Contractile Vacuoles

The pressure that water molecules exert against the cell wall Turgor pressure

The shrinking of a cell due to water’s moving out the cell when placed in a hypertonic environment Plasmolysis

The swelling and eventual bursting of a cell as water moves into it when placed in a hypotonic environment Cytolysis

Facilitated Diffusion The movement of substances across a cell membrane with the assistance of protein carriers Facilitated Diffusion

The proteins that move certain molecules into the cell that cannot readily diffuse through the cell membrane Carrier Proteins

A complex of protein molecules in a cell membrane that form a pore through which ions can pass Ion Channels

The movement of chemical substances, usually across the cell membrane, against a concentration gradient; requires energy Active Transport

Sodium-Potassium Pump A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell Sodium-Potassium Pump

The process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell Endocytosis

Small cavity or sac that contains materials; forms when part of the membrane surrounds the materials to be taken into or out of the cell Vesicle

A method of active transport across the cell membrane in which the cell takes in extracellular fluids Pinocytosis

The process by which a cell engulfs large particles or whole cells, either as a defense mechanism or as a means to obtain food Phagocytosis

A cell that ingests and destroys (digests) foreign matter or microorganisms Phagocyte

The process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out Exocytosis