3: the plasma membrane and membrane potential

Question 1

functions of the plasma membrane

Answer 1

mechanical barrier
selectivity
maintains differences in ion concentrations

Question 2

characteristics of the lipid bilayer

Answer 2

forms the basic structure of the membrane
hydrophobic interior is a barrier to passage of water soluble substances between the ECF and ICF
responsible for the fluidity of the membrane

Question 3

fluid mosaic model

Answer 3

refers to membrane fluidity and pattern of proteins embedded in the membrane

Question 4

phospholipids

Answer 4

phosphate head (- charge)
3 fatty acid chain tail (no charge)

Question 5

proteins

Answer 5

allow charged molecules into the cell through protein channels

Question 6

cholesterol

Answer 6

contributes to the fluidity and stability of the membrane

Question 7

carbohydrates

Answer 7

allow for recognition/signal to other cells

Question 8

leak channels

Answer 8

always open and permit passage of their selected ion

Question 9

gated channels

Answer 9

can be opened or closed (voltage gated+mechanically gated)

Question 10

agonist gated

Answer 10

has specific binding site, chemical must bind for it to be opened

Question 11

carrier molecules

Answer 11

transfer specific substances across the membrane that are unable to cross on their own

Question 12

cell adhesion molecules

Answer 12

bind cell to cell, and help keep internal cell fibers in the correct location

Question 13

desmosomes

Answer 13

physically extend intracellular filaments to connect cell membranes

Question 14

tight junctions

Answer 14

allow nothing to pass between them and have highly selective barriers

Question 15

gap junctions

Answer 15

a gap exists between adjacent cells. linked by small tunnels called connexons

Question 16

passive vs active transport

Answer 16

does not require ATP, requires ATP

Question 17

diffusion

Answer 17

solute will travel to a less concentrated area of the solution

Question 18

osmosis

Answer 18

the net diffusion of water down its concentration gradient through a selectively permeable membrane

Question 19

osmotic pressure

Answer 19

the tendency for osmotic flow of water into a solution

Question 20

facilitated diffusion

Answer 20

carrier mediated transport

Question 21

primary active transport

Answer 21

energy in the form of ATP is required for the carrier to change shape and alternately expose the carrier’s binding sites for ion to opposite sides of the membrane

Question 22

secondary active transport

Answer 22

the carrier does not split the atp to move a substance against its concentration gradient

Question 23

endocytosis

Answer 23

the plasma membrane surrounds the substance to be ingested, pinching off a membrane enclosed vesicle so the engulfed material is trapped within the cell

Question 24

exocytosis

Answer 24

a membrane enclosed vesicle formed within the cell fuses with the plasma membrane, then opens up and releases its contents to the exterior