Chapter 5

Question 1

A property of biological membranes that allows them to regulate the passage of substances across them

Answer 1

Selective permeability

Question 2

Having both a hydrophilic and hydrophobic region

Answer 2

Amphipathic

Question 3

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

Answer 3

Fluid mosaic model

Question 4

A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane

Answer 4

Integral proteins

Question 5

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

Answer 5

Peripheral proteins

Question 6

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

Answer 6

Transport proteins

Question 7

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

Answer 7

Channel proteins

Question 8

A type of transport proteins that hold on to passengers and change their shape to shuttle molecules across the membrane

Answer 8

Carrier proteins

Question 9

A channel protein in the plasma membrane of a plant, animal, or microorganism call that specifically facilitates osmosis, the diffusion of free water across a membrane

Answer 9

Aquaporin

Question 10

The random thermal motion of particles of liquids, gases, or solids. In the presence of a concentration or electrochemical gradient, this results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated

Answer 10

Diffusion

Question 11

The diffusion of free water molecules across a selectively permeable membrane

Answer 11

Osmosis

Question 12

A region along which the density of a chemical substance increases or decreases

Answer 12

Concentration gradient

Question 13

The diffusion of a substance across a biological membrane with no expenditure of energy

Answer 13

Passive transport

Question 14

The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure

Answer 14

Facilitated diffusion

Question 15

The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy

Answer 15

Active transport

Question 16

The ability of a solution surrounding a cell to cause that cell to gain or lose water

Answer 16

Tonicity

Question 17

The difference in electrical charge across a cell’s plasma membrane due to the differential distribution of ions. Affects the activity of excitable cells and the transmembrane movement of all charged substances

Answer 17

Membrane potential

Question 18

An active transport protein that generates voltage across a membrane while pumping ions

Answer 18

Electrogenic pump

Question 19

The coupling of downhill diffusion of one substance to the uphill transport of another against its own concentration gradient

Answer 19

Cotransport

Question 20

The cellular secretion of biological molecules by the fusion of vesicles containing them to the plasma membrane

Answer 20

Exocytosis

Question 21

Cellular uptake of biological molecules and articulate matter via formation of vesicles from the plasma membrane

Answer 21

Endocytosis