Topic 10

Question 1

Plasma membranes contain ______ which control cell to cell signaling thus mediating interactions between the cell and the environment by acting as __________.

Answer 1

proteins, sensors

Question 2

Studies of _________________ provided the first evidence that biological membranes consist of lipid bilayers, and provided a simple model for membrane study

Answer 2

mammalian RBC plasma membrane

Question 3

Two basic categories of membrane proteins:

Answer 3

peripheral and integral

Question 4

peripheral membrane proteins

Answer 4

proteins that dissociate from membrane following treatments that do not disrupt the bilayer

Question 5

integral membrane proteins

Answer 5

can be released only by experimental treatments such as amphipathic detergents that disrupt the bilayer

Question 6

plasma membrane proteins association with _______ elements may anchor regions of membranes to a defined location, and help determine cell shape

Answer 6

cytoskeletal

Question 7

lipid rafts

Answer 7

together with p.m proteins make functional domains within the bilayer

Question 8

polarized cells

Answer 8

need to be anchored in place to maintain function of the cell

Question 9

Orientation and separation of membrane domains occurs through ______________ between cells.

Answer 9

specialized junctions

Question 10

glycophorin

Answer 10

associated with cytoskeleton at actin/spectrin junctions via protein 4.1

Question 11

Band 3

Answer 11

bicarbonate and chloride transporter critical for CO2 uptake by RBC; associated with spectrum via Ankyrin

Question 12

lipid rafts create ______________ within plasma membrane

Answer 12

specialized functional domains

Question 13

define polarized cells

Answer 13

cells with different structural and functional faces at opposite ends of the cell; these regions are divided into apical and basolateral domains

Question 14

tight junctions

Answer 14

separate apical and basal regions of membrane and prevent protein diffusion

Question 15

apical domain

Answer 15

nutrient uptake from lumen

Question 16

basolateral domain

Answer 16

nutrient transfer to capillaries

Question 17

passive diffusion

Answer 17

movement of membrane permeable molecules (small, non-polar) along a conc. gradient; non-selective, no energy required

Question 18

facilitated diffusion

Answer 18

assisted transport for molecules that are not soluble in bilayer

Question 19

carrier proteins

Answer 19

bind specific molecules to be transported

Question 20

channel proteins

Answer 20

form open pores through the membrane, allowing the free diffusion of any molecule of the appropriate size and charge

Question 21

active transport

Answer 21

transport of molecules across an energetically unfavourable direction

Question 22

ion pumps

Answer 22

responsible for maintaining gradients of ions

Question 23

Na+ conc. inside cell

Answer 23

10 mM

Question 24

Na+ conc. outside cell

Answer 24

145 mM

Question 25

K+ conc. inside cell

Answer 25

140 mM

Question 26

K+ conc. outside cell

Answer 26

5 mM

Question 27

Cl- conc. inside cell

Answer 27

4 mM

Question 28

Cl- conc. outside cell

Answer 28

110 mM

Question 29

Sodium/Potassium pump moves __ Na+ ___ for every __ K+ __.

Answer 29

3, out; 2, in

Question 30

pinocytosis

Answer 30

cell drinking; uptake of fluids or macromolecules in small vesicles

Question 31

Receptor-mediated endocytosis

Answer 31

form of pinocytosis; relies on specific cell surface receptors that recognize molecules/particles to be taken up

Question 32

phagocytosis

Answer 32

cell eating; ingestion of large particles such as bacteria

Question 33

LDL

Answer 33

low density lipoprotein; particle used to transport cholesterol through the bloodstream to target cells

Question 34

LDL makeup

Answer 34

• cholesterol esters in core
• surrounded by phospholipids and cholesterol
• one molecule of ApoB protein on surface