b200 ch07 f24 lecture figs(1)

Aquaporin

A water channel protein in the membrane that facilitates water transport.

Fluid Mosaic Model

A model that describes the structure of cell membranes as stable yet dynamic, with components that can move laterally.

Phospholipid Bilayer

A double layer of phospholipids that makes up the cell membrane, providing a barrier to water-soluble substances.

Integral protein

A membrane protein that extends into or completely spans the phospholipid bilayer.

Peripheral protein

A membrane protein that does not penetrate the lipid bilayer and is associated with the surface.

Cholesterol

A steroid that is interspersed within the phospholipid bilayer, affecting membrane fluidity.

Membrane fluidity

The viscosity of the lipid bilayer of a cell membrane that affects its flexibility and the movement of proteins within.

Selectively Permeable

A property of cell membranes that allows certain substances to pass through while blocking others.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a solution to cause a cell to gain or lose water, including isotonic, hypertonic, and hypotonic solutions.

Facilitated Diffusion

The process of spontaneous passive transport of molecules across a biological membrane via specific transmembrane proteins.

Active Transport

The process of moving molecules against their concentration gradient, requiring energy (ATP).

Cotransport

The coupling of the transport of one substance to the transport of another across a membrane.

Endocytosis

The process by which cells engulf material from the outside environment by enclosing it in a vesicle.

Exocytosis

The process by which cells secrete materials to the external environment using vesicles.

Ion Pumps

Membrane proteins that transport ions across the membrane, often against their concentration gradient.

Electrochemical Gradient

The gradient produced by the combined effect of ion concentration and electrical charge differences across the membrane.

Proton Pump

A type of ion pump that moves protons (H+) across a membrane, creating a proton gradient.