Cell Biology Osmosis and Diffusion

Biology Study

Osmosis

The diffusion of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower concentration

Hypotonic

The solution with the lower solute concentration when comparing two solutions of unequal solute concentration

Hypertonic

The solution with the higher solute concentration when comparing two solutions of unequal solute concentration

Isotonic

Solutions of equal solute concentration

Selectively permeable

The ability to allow only certain molecules or ions to cross the plasma membrane, semipermeable

Concentration gradient

The difference in the concentrations of molecules across a membrane

Diffusion

The tendency of molecules to move from an area of high concentration to an area of low concentration until the concentration is uniform

Plasmolysis

Process in which the cell membrane pulls away from the cell wall as a cell shrivels when placed in a hypertonic solution

Contractile vacuole

A type of vacuole that removes excess water from a cell; found in organisms that live in hypotonic environments such as freshwater paramecium (freshwater protist)

Transport proteins

Proteins that facilitate the movement of substances across a cell membrane, either through passive or active transport mechanisms. protein in a cell membrane that helps molecules pass through the membrane, by either forming a channel for the molecules or carrying the molecules through the membrane

Passive transport

Movement of substances across a plasma membrane that does not require energy because the substance is moving from a higher or lower concentration

Hydrophobic

Water fearing

Hydrophilic

Water loving

Active transport

Movement of substances across a plasma membrane that requires energy because the substance is moving against the concentration gradient, from a lower to higher concentration