OP: Regulation

Question 1

describe flow of electrons

Answer 1

the e- flows from the molecules w/ lower E0 to that w/ highest E0

Question 2

E0

Answer 2

standard redox potential

difference in E0 is associated w/ gibbs nrg and they are inversely related

G = -nf(delta)E0

Question 3

establishing a proton gradient

Answer 3

e- transfer thru the ETC leads to pumping H+ from matrix to innermemb space

2 factors cause the proton motive force (pmf) to drive ATP synthesis by complex V

Question 4

pmf

Answer 4

proton motive force

• -the 2 factors involved that drive protons from matrix to inner memb space
• -also the chemiosmotic hypothesis

pH gradient
memb potential

Question 5

3 postulates of the chemiosmotic theory

Answer 5

1. the mito ETC translocates protons across the inner memb as e- flows from one e- carrier to the next
2. ATP synthase uses the pmf to drive the phosphorylation of ADP
3. inner mito memb is impermeable to H+ or OH- ions. if the memb is disrupted, pmf cannot be created and ATP cannot be made

Question 6

structure of ATP synthase

Answer 6

= complex V
embedded in inner memb
F0 = embedded in memb
F1 = protrudes into matrix side, contains the catalytic domains
(subunits)

Question 7

F1 subunits

Answer 7

a3, b3, y, d, e

• -a and b arranged alternately in hexagon
• -above a/b is a y/e stalk
• -both bind nucleotides, b is catalytically active

Question 8

ATP synthase properties

Answer 8

• -form homodimers
• -dimers join to form oligomers
• -maintains curves of inner memb
• -cristae allow the proton gradient to be in close proximity to the ATP synthase

Question 9

synthesis of ATP

Answer 9

• -catalyzed by a large memb bound protein

- -harness the nrg contained in pmf, ATP synthase obtains necessary power to form ATP = 7.3 kcal/mol

Question 10

oligomycin

Answer 10

an inhibitor of ATP synthesis

disrupts proton transport thru the channel

Question 11

mechanism of action of ATP-ADP translocase

Answer 11

–they are not permeable across mito memb, thus need a carrier
–ATP-ADP translocase family
…….are in outer/inner mito membs
–flow of ATP and ADP is coupled, ADP only enters matrix if ATP leaves (also complex VI)

Question 12

reduced NADH cannot cross the ?

Answer 12

mito memb
so uses 2 shuttle systems
1. malate-aspartate shuttle
2. glycerophosphate shuttle

Question 13

malate-aspartate shuttle

Answer 13

operates in heart, liver, kidneys

generates NADH in mito-matrix

NADH enters to ETC at complex I

Question 14

glycerophosphate shuttle

Answer 14

operates in skeletal muscle, brain

generates FADH2 in the inner mito memb

FADH2 joins to ETC at CoQ

Question 15

regulation of cellular respiration

Answer 15

• -levels of ATP regulate respiration
• -e- can only flow thru ETC when ADP is phosphorylated

regulation by ADP levels called respiratory control or acceptor control

Question 16

inhibition of OxPhos

Answer 16

when transfer of e-‘s is inhibited

• -a decrease in the pumping protons
• -a decrease in the protein gradient
• -inhibition of ATP synthesis

Question 17

uncoupling and heat generation – hibernating animals

Answer 17

some organisms can uncouple oxphos from ATP synthesis used to generate heat and maintain body temp
–happens in brown adipose tissue

Question 18

uncoupling protein

Answer 18

inner mito memb contains uncoupling protein = thermogenin (UCP 1)

transfers protons from cytoplasm to matrix side
–nrg converted to heat

UCP 2 and UCP 3 also uncouple oxphos from ATP synthesis – playing a role in nrg homeostasis