Bennett Biology - Cell membrane

cell membrane

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

plasma membrane

Another name for the cell membrane.

fluid mosaic

A model that says the cell membrane tends to act more like a liquid than a solid and has proteins embedded in it.

passive transport

Movement across the cell membrane that does not require energy from the cell and moves with the concentration gradient.

active transport

Energy-requiring process that moves material across a cell membrane against a concentration gradient.

diffusion

Movement of molecules (oxygen, caron dioxide, natural steroid hormones) from an area of higher concentration to an area of lower concentration.

osmosis

Diffusion of water from an area of higher concentration to an area of lower concentration. .

endocytosis

Movement of materials into the cell by the formation of a vesicle from the infolding of the cell membrane.

exocytosis

Removal or secretion of materials from a cell by use of a vesicle. The molecules to be exported are modified by the Golgi body

lipid bilayer

Term used to describe the 2 layer thick phospholipid structure of the cell membrane.

phospholipid

Specialized lipid made of a hydrophilic (polar) phosphate head and two hydrophobic (nonpolar) fatty acid tails.

hydrophobic

Describes a substance that resists dissolving in water.

hydrophilic

Describes a substance that is able to mix with water.

isotonic

Describes a solution whose solute concentration is equal to the solute concentration inside a cell. No change in the cell shape.

hypotonic

Describes a solution whose solute concentration is lower than the solute concentration inside a cell. Causes a cell to swell or increase in size from water entering into the cell.

hypertonic

Describes a solution whose solute concentration is higher than the solute concentration inside a cell. Causes a cell to shrink in size from water exiting a cell.

channel proteins

A type of transport protein in the membrane whose role is to pass large molecules (ions, sugars, & amino acids) that cannot go through the membrane.

protein pump

Transport protein used to move substances against the gradient.

marker protein

A special type of protein found in the cell membrane that helps to identify a cell.

facilitated diffusion

A type of passive transport that uses a transport protein to move substances down the concentration gradient.

homeostatsis

The maintenance of stable internal conditions in a changing environment.

equilibrium

Spaced is filled with the same amount of molecules on the inside as there are on the outside.

concentration gradient

substances move from an area of high concentration to an area of low concentration

carrier protein

A type of transport protein in the membrane whose role is to only pass substances through the cell membrane that can fit their binding sites.

concentration

The amount of a particular substance in a given volume.

sodium-potassium pump

ATP (energy) is used to pump sodium ions outside of the cell and potassium ions inside the cell.

vesicles

Membrane bound sacs.