membranes

Question 1

define comatmentalisation

Answer 1

formation of separate membrane bound areas in a cell

allows specific condo.s for cellular reactions

Question 2

what is the role of cholesterol in plasma membranes

Answer 2

lipid
positioned between phospholipids
hydrophilic end interacts with phospholipid head and hydrophobic end interacts with tail
prevents membrane becoming too solid by stopped phospholipids grouping too closely

Question 3

describe intrinsic membrane proteins

Answer 3

in both layers
amino acids with hydrophobic R groups (on external surface)
interact with hydrophobic core

Question 4

describe extrinsic membrane proteins

Answer 4

on one side of bilayer
amino acids have hydrophilic R groups
interact with heads

Question 5

describe carrier + channel proteins

Answer 5

involved in active transport
channel
-provides hydrophilic channel which allows movement of polar mol.s down conc. grad. through membrane

Question 6

describe glycoproteins

Answer 6

attached carb chain
receptors for chemical signals
elicits response from cell

Question 7

what effect do organic solvents have on phospholipid bilayers

Answer 7

dissolve them

Question 8

define diffusion

Answer 8

net overall movement from an area of high conc. to low conc.
passive process
continues until equilibrium is reached

Question 9

name factors affecting diffusion

Answer 9

simple= absence of barrier
-temp
-conc. difference
across membrane
-SA (positive correlation)
- thickness

Question 10

describe facilitated diffusion

Answer 10

does NOT require energy
carrier proteins change shape when specific mol binds
polar mols pass through channel proteins
selectively permeable membranes

Question 11

describe active transport

Answer 11

mol binds to receptors in channel of carrier protein outside cell
inside cell- ATP bind to carrier protein and is hydrolysed to ADP + phosphate
protein changes shapes +opens on inside of cell
mol released inside cell
phosphate mol released and recombines with ADP
proteins returns shape

Question 12

what is bulk transport into cell called

Answer 12

endocytosis

Question 13

name 2 types of endocytosis

Answer 13

phagocytosis

pinocytosis

Question 14

describe the difference between endocytosis and exocytosis

Answer 14

endo
-membrane enfold material until it fuses forming vesicle
-pinches off and moves into cytoplasm
ego
-vesicle formed by Golgi apparatus
-moves towards + fuses with membrane

Question 15

define solute

Answer 15

substance dissolved in solute

Question 16

define concentration (osmosis)

Answer 16

amount of solute in volume of aqueous solution

Question 17

define water potential

Answer 17

pressure exerted by water mol.s as they collide wth membrane
measure in Pa/kPa

Question 18

name for animal cells when there is lots/lack of water

Answer 18

lots= cytolysis
lack= creation

Question 19

name for plant cells when there is lots/lack of water

Answer 19

lots= turgid
lack= plasmolyse