Bio - Chap 7

Front 1

active transport

Back 1

The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.

Front 2

amphipathic molecule

Back 2

A molecule that has both a hydrophilic region and a hydrophobic region.

Front 3

concentration gradient

Back 3

An increase or decrease in the density of a chemicalsubstance in an area.

Front 4

diffusion

Back 4

The spontaneous tendency of a substance to move down its concentrationgradient from a more concentrated to a less concentrated area

Front 5

endocytosis

Back 5

The cellular uptake of macromolecules and particulate substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle.

Front 6

exocytosis

Back 6

The cellular secretion of macromolecules by the fusion of vesicles withthe plasma membrane.

Front 7

facilitated diffusion

Back 7

The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.

Front 8

flaccid

Back 8

Limp. A walled cell is flaccid in surroundings where there is no tendency forwater to enter.

Front 9

fluid mosaic model

Back 9

The currently accepted model of cell membrane structure,which envisions the membrane as a mosaic of individually inserted proteinmolecules drifting laterally in a fluid bilayer of phospholipids.

Front 10

glycolipid

Back 10

A lipid covalently attached to a carbohydrate.

Front 11

glycoprotein

Back 11

A protein covalently attached to a carbohydrate

Front 12

hypertonic

Back 12

In comparing two solutions, referring to the one with a greater solute concentration.

Front 13

hypotonic

Back 13

In comparing two solutions, referring to the one with a lower soluteconcentration.

Front 14

integral protein

Back 14

Typically a transmembrane protein with hydrophobic regions that completely spans the hydrophobic interior of the membrane.

Front 15

ion channel

Back 15

Protein channel in a cell membrane that allows passage of a specific ion down its concentration gradient.

Front 16

osmosis

Back 16

The diffusion of water across a selectively permeable membrane

Front 17

passive transport

Back 17

The diffusion of a substance across a biological membrane.

Front 18

peripheral protein

Back 18

A protein appendage loosely bound to the surface of a membrane and not embedded in the lipid bilayer.

Front 19

phagocytosis

Back 19

A type of endocytosis involving large, particulate substances.

Front 20

plasmolysis

Back 20

A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall when the cell loses water to a hypertonic environment.

Front 21

receptor-mediated endocytosis

Back 21

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sitesspecific to the molecules being taken in

Front 22

selective permeability

Back 22

A property of biological membranes that allows some substances to cross more easily than others.

Front 23

sodium-potassium pump

Back 23

A special transport protein in the plasma membrane ofanimal cells that transports sodium out of the cell and potassium into the cellagainst their concentration gradients

Front 24

tonicity

Back 24

The ability of a solution to cause a cell within it to gain or lose water.

Front 25

transport protein

Back 25

A transmembrane protein that helps a certain substance or classof closely related substances to cross the membrane.

Front 26

turgid

Back 26

Very firm. A walled cell become turgid if it has a greater solute concentration than its surroundings, resulting in entry of water.