Histology Lecture 8: Cytoskeleton and Cell Membrane I

Question 1

consists of a phospholipid bilayer in which are embedded or attached a wide variety of proteins and glycoproteins

Answer 1

unit membrane

Question 2

defines the boundary of the cell and separates it from the environment; is selective and determines the composition of the intracellular environment; mediates interactions between the cell and its environment

Answer 2

cell membrane

Question 3

formed from a neutral fat in which one of the fatty acid groups on the glycerol moiety is replaced by a phosphate group; consists of a hydrophilic head and two hydrophobic tails

Answer 3

phospholipid

Question 4

second most common membrane lipid; hydrophobic; contains a polar hydroxyl group (hydrophilic) that draws it to the polar heads of two adjacent phospholipids

Answer 4

cholesterol

Question 5

found predominantly in the outer leaflet of the phospholipid bilayer

Answer 5

phosphatidylcholine and sphingomyelin

Question 6

negatively charged phospholipids found predominantly in the inner leaflet of the phospholipid bilayer lending net negative charge to cytosolic face of the plasma membrane

Answer 6

phosphatidylserine and phosphatidylinositol

Question 7

has an effect on membrane fluidity by modulating the movement of the fatty acid chains of phospholipids in a temperature dependent manner

Answer 7

cholesterol

Question 8

found exclusively in the outer leaflet with carbohydrate portion facing extracellular environment; fatty acid tail is coupled via sphingosine to a carbohydrate head group; create a cell coat involved in cell-to-cell interaction and conveys antigenicity

Answer 8

glycolipids

Question 9

conditions under which cholesterol interferes with fatty acid chain movement, makes outer part of membrane less fluid, and reduces the permeability of the membrane to small molecules

Answer 9

high temperatures (cholesterol)

Question 10

conditions under which cholesterol prevents membranes from freezing and maintains membrane fluidity

Answer 10

low temperatures (cholesterol)

Question 11

carbohydrate coat on the extracellular surface of the cell membrane composed of carbohydrate portions of glycolipids and glycoproteins

Answer 11

glycocalyx

Question 12

small patches of cholesterol and spingolipids (sphingomyelin and glycolipids) that serve as landing sites for molecules destined for phagocytosis

Answer 12

lipid rafts

Question 13

associated with membranes through protein-protein interactions typically involving ionic bonds that can be dissociated from the membrane

Answer 13

membrane proteins

Question 14

proteins that are inserted into the membrane and that can only be dissociated by reagents that disrupt hydrophobic interactions; interact with hydrophobic core of the protein; embedded within the phopholipid bilayer; extracellular portion is typically glycosylated

Answer 14

integral membranes

Question 15

peripheral proteins attached to the membrane by GlycoPhosphatidylInositiol

Answer 15

GPI-anchored proteins

Question 16

found on both the outer and inner leaflets of the cell membrane facing either the extracellular or intracellular fluid; can be removed with detergents

Answer 16

peripheral proteins

Question 17

pass completely through both phospholipid layers; typically serve as channel and transporter proteins

Answer 17

transmembrane proteins

Question 18

movement of particles from high to low concentrations; does not require energy or transports

Answer 18

diffusion

Question 19

diffusion of solvent (typically water) across a semipermeable membrane; does not require energy or transport molecules

Answer 19

osmosis

Question 20

a type of diffusion that requires transport molecules from areas of high concentration to low concentrations; does not require energy

Answer 20

facilitated diffusion

Question 21

movement against a concentration gradient and requires energy and transport molecules

Answer 21

active transport

Question 22

transport protein that carries single molecule or ion unidirectionally

Answer 22

unitransporter

Question 23

co-transport protein that carries two molecules or ions simultaneously or sequnetially in the same direction

Answer 23

symporter

Question 24

co transport protein that carries two molecules or ions simultaneously or sequentially in the opposite direction

Answer 24

antiporter