Chapter 6: Cell Membranes

Question 1

Fluid Mosaic Model

Answer 1

General Structure of membranes

Question 2

phospholipid bilayers

Answer 2

flexible, the interior is fluid, allows lateral movement of molecules

Question 3

peripheral membrane proteins

Answer 3

lack exposed hydrophobic groups and so not penetrate the bilayer

Question 4

integral membrane proteins

Answer 4

have hydrophobic and hydrophilic regions or domains. Some extend across the lipid bilayer; others are partially embedded.

Question 5

transmembrane proteins

Answer 5

extend all the way through the phospholipid bilayer. they have one or more transmembrane domains

Question 6

glycolipids

Answer 6

carbohydrate + lipid

Question 7

glycoproteins

Answer 7

carbohydrate + protein; are involved in cell recognition and binding

Question 8

tight junctions

Answer 8

help ensure directional movement of materials

Question 9

desmosomes

Answer 9

like “spot welds”, small openings in the bilayer

Question 10

gap junctions

Answer 10

allow cell communication

Question 11

passive transport

Answer 11

no outside energy required (diffusion)

Question 12

active transport

Answer 12

energy required

Question 13

diffusion

Answer 13

the process of random movement towards equilibrium

Question 14

equilibrium

Answer 14

particles continue to move, but there is no net change in distribution. net movement is directional until equilibrium is reached.

Question 15

simple diffusion

Answer 15

small molecules pass through the lipid bilayer

Question 16

osmosis

Answer 16

the diffusion of water

Question 17

hypotonic

Answer 17

high solute concentration

Question 18

isotonic

Answer 18

equal solute concentration

Question 19

hypertonic

Answer 19

lower solute concentration

Question 20

cannel proteins

Answer 20

have central pore lined w polar amino acids

Question 21

carrier proteins

Answer 21

membrane proteins that bind substance and speed diffusions through the bilayer

Question 22

ion channels

Answer 22

specific channel proteins w hydrophobic pores

Question 23

gated

Answer 23

can be closed or open to ion passage

Question 24

membrane potential

Answer 24

charge imbalance across a membrane, membrane potential is related to K+ concentration imbalance

Question 25

facilitated diffusion

Answer 25

carrier proteins transport polar molecules across membranes

Question 26

active transport

Answer 26

moves substance against a concentration and/or electrical gradient- requires ATP

Question 27

primary active transport

Answer 27

requires ATP

Question 28

Secondary Active Transport

Answer 28

energy comes from ion concentration gradient established but PAT (primary active transport)

Question 29

sodium-potassium pump

Answer 29

PAT, an integral membrane glycoprotein (an anti porter)

Question 30

endocytosis

Answer 30

brings larger molecules into a eukaryotic cell, forms a vesicle

Question 31

phagocytosis

Answer 31

molecules entirely engulfed, white blood cells engulf foreign substance, phagosome forms, and fuses with lysosome

Question 32

pinocytosis

Answer 32

vesicle forms to bring small dissolved substances or fluids into a cell.

Question 33

receptor mediated endocytosis

Answer 33

depends on receptor proteins that bind to specific substances, sites are called coated pits

Question 34

exocytosis

Answer 34

material in vesicle is expelled (reverse of endocytosis)

Question 35

endothelial

Answer 35

capillary cells