transport across cell membrane (2)

Question 1

membrane function

Answer 1

control composition of space surrounded by membrane

providing route for polar and large molecules - cross membrane

Question 2

proteins in the membrane

Answer 2

channels, transporters, receptors, structural protein

Question 3

peripheral transmembrane protein

Answer 3

loosely associated to bilayer

bound by electrostatic interaction

Question 4

integral transmembrane protein

Answer 4

embedded in bilayer

Question 5

alpha-helical in membrane

Answer 5

cross HP core of bilayer

R group of side chains interact with bilayer - anchoring

Question 6

what favours aqueous in cells

Answer 6

hydrophilic groups

Question 7

charges in centre of bilayer

Answer 7

no charge

makes VdW forces between HP lipids and side chain

Question 8

max H bonding function in protein

Answer 8

neutralise charges NH and CO in protein backbone

Question 9

what can peptide adopt

Answer 9

finding lowest energy conformation

Question 10

transmembrane helices anchor membrane protein

Answer 10

protein sequences is HP

R group project out - face lipids - anchored

Question 11

producing path for polar solutes

Answer 11

amphipathic helices cluster together - route

at least 4 helices

Question 12

entry of channel - function

Answer 12

charged

determine types of charges approach channel

Question 13

glycine - in producing path of helices

Answer 13

help packing amphipathic helices together

Question 14

polar channel - transport ion

Answer 14

alpha helices charged residue on one side and HP on other side

Question 15

simple gated ion channel - closing

Answer 15

helices rotate - larger side chains towards centre

Question 16

ligand gated ion channel - conformation

focused on N2 transmembrane domain

Answer 16

closing and opening conformation is triggered by binding of acetylcholine
neurotransmitters

Question 17

what channels can’t do

Answer 17

move ion against electrochemical gradient

facilitated diffusion like glucose and amino acids

Question 18

use of transporters - towards substrates and function

Answer 18

reduction in affinity for substrate
has solute recognition site = large conformational change
opens gated below and closes above - never both

Question 19

passive transport

Answer 19

down gradient

Question 20

example of passive transport

Answer 20

facilitated diffusion - binds to substrate = conformational change moving substrate down concentration gradient

Question 21

active

Answer 21

against gradient

energy from electrochemical gradient or energy rich substrate - ATP

Question 22

example of active

Answer 22

active transport - bind to substrate - provide energy causing conformational change

Question 23

atomic resolution structure of Ca2+ pump

Answer 23

10 alpha helices across bilayer

Question 24

calcium ATPase

Answer 24

assimilating Ca2+ in sarcoplasmic reticulum pump Ca2+ into calcium store - muscle tissues

Question 25

process of Ca2+ pump (1)

Answer 25

calcium ATPase binds to Ca2+ from cytoplasmic side with high affinity

Question 26

Using ATP hydrolysis (2)

Answer 26

conformational change - close access of cytoplasmic side

conversion of high to low affinity site - opening hydrophilic cavity to lumen of sarcoplasmic reticulum

Question 27

energy released by ATP hydrolysis (3)

Answer 27

weaken grip of high affinity from Ca2+ by conformational change around amphipathic helices