Chapter 6

Question 1

glycerol

Answer 1

Glycerol consists of a propane molecule attached to three hydroxyls that form the backbone of phospholipids and most fats

Question 2

ester linkage

Answer 2

the covalent formed by a condensation reaction between a carboxyl group and a hydroxyl group, joins fatty acids to glycerol

Question 3

steroid

Answer 3

a class of lipid with characteristic four ring structure

Question 4

cholesterol

Answer 4

a compound of the sterol type found in most body tissues. Cholesterol and its derivatives are important constituents of cell membranes and precursors of other steroid compounds, but a high proportion in the blood of low-density lipoprotein (which transports cholesterol to the tissues) is associated with an increased risk of coronary heart disease.

Question 5

amphipathic

Answer 5

containing hydrophilic and hydrophobic elements

Question 6

hydrocarbon tail

Answer 6

tail of a lipid that only contains hydrogen and carbon and is nonpolar

Question 7

polar head group

Answer 7

region of the lipid molecule that is hydrophilic

Question 8

selective permeability

Answer 8

the property of a membrane that allows some substances to diffuse across it much more readily than others

Question 9

micelle

Answer 9

an aggregate of molecules in a colloidal solution, such as those formed by detergents.

Question 10

saturated lipid

Answer 10

referring to fatty acids in which all the carbon carbon bonds are single bonds

Question 11

liposome

Answer 11

a minute spherical sac of phospholipid molecules enclosing a water droplet

Question 12

transmembrane proteins

Answer 12

another name for integral membrane protein

Question 13

peripheral membrane protein

Answer 13

any proteins that does not span the entire lipid bilayer and only associates with one side of the bilayer

Question 14

gel electrophoresis

Answer 14

a technique for separating molecules on the basis of size and electric charge which affect their differing rates of movement through a gelatinous substance in an electric field

Question 15

detergent

Answer 15

a type of small amphipathic molecule used to solubilize hydrophobic molecules in aqueous solution

Question 16

membrane fluidity

Answer 16

refers to the viscosity of the lipid bilayer of a cell membrane

Question 17

transport protein

Answer 17

collective term for any membrane protein that enables a specific ion or small molecule to cross a plasma membrane. Includes carrier proteins and channel proteins, which carry out passive transport and pumps which carry out active transport

Question 18

facilitated diffusion

Answer 18

movement of a substance across a plasma membrane down its concentration gradient with the assistance of trans-membrane carrier proteins and channel proteins

Question 19

secondary active transport

Answer 19

transport of an ion or molecule against its electrochemical gradient, in company with an ion or molecule being transported with its electrochemical gradient

Question 20

cotransport

Answer 20

another name for secondary active transport

Question 21

channel protein

Answer 21

a protein that forms a pore in a cell membrane, the structure of most channels allow them to submit just one or a few types of ions and molecules

Question 22

ion channel

Answer 22

a type of channel protein that allows certain ions to diffuse across a plasma membrane down an electrochemical gradient

Question 23

gated channel

Answer 23

a channel protein that opens and closes in response to a specific stimulus, such as the binding of a particular molecule or a change in the electrical charge on the outside of the membrane

Question 24

carrier protein

Answer 24

a membrane protein that facilitates diffusion of a small molecule across the plasma membrane by a process involving a reversible change in the shape of a protein

Question 25

electrochemical gradient

Answer 25

the combined effect of an ion’s concentration gradient and electrical gradient across a membrane that affects the diffusion of ions across the membrane

Question 26

cystic fibrosis

Answer 26

genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections.

Question 27

aquaporin

Answer 27

a type of channel protein through which water can move by osmosis across a plasma membrane

Question 28

sodium-potassium pump

Answer 28

a transmembrane protein that uses the energy of ATP to move sodium ions out of the cell and potassium ions in