Cell membrane

cell membrane

A cell structure that controls which substances can enter or leave the cell.

Homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

Phospholipid Bilayer

A double layer of phospholipids that makes up plasma and organelle membranes.

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

Hydrophobic tails

directed toward the center, avoiding water

Hydrophilic head

Water-attracting part of a phospholipid.

integral proteins

penetrate the hydrophobic interior of the lipid bilayer typically carrier/transport proteins

peripheral proteins

The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.

cholesterol

A lipid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids.

Carbohydrate chains

provide a "fingerprint" for the cell, so it can be recognized by other cells

Glycoproteins

A protein with one or more covalently attached carbohydrates.

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

Diffusion

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

Osmosis

Diffusion of water through a selectively permeable membrane

Isotonic

when the concentration of two solutions is the same

Hypotonic

Referring to a solution that, when surrounding a cell, will cause the cell to take up water.

Hypertonic

Referring to a solution that, when surrounding a cell will cause the cell to lose water

facilitated diffusion

process of diffusion in which molecules pass across the membrane through cell membrane channels

active transport

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

bulk transport

The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis

Exocytosis

Process by which a cell releases large amounts of material

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane