Respiration III 10/5

Question 1

why is it important that metabolic pathways involve many enzyme catalyzed steps?

Answer 1

allows for ATP conservation

Question 2

why is it important that metabolic pathways are interconnected?

Answer 2

allows for efficient utilization of metabolites (nothing goes to waste!)

Question 3

flux thru a pathway is controlled by 3 things. they are:

Answer 3

1. enzymes in the pathway
2. supply of the starting material
3. rate of product utilization

*flux thru pathway is never faster than SLOWEST STEP (rate limiting step)

Question 4

fuel for acetyl coA comes from:

Answer 4

1. pyruvate
2. amino acids
3. fatty acids

Question 5

substrate of TCA

Answer 5

acetyl coA

Question 6

products of TCA

Answer 6

NADH, FADH₂, ATP

Question 7

TCA is regulated by…

Answer 7

allosteric regulation

Question 8

TCA is driven by

Answer 8

substrate availability and product utilization

Question 9

3 sites of control of the TCA

Answer 9

1. acetyl CoA + oxaloacetate → citrate
2. isocitrate →alpha-ketoglutarate
3. alphaketoglutarate →succinyl CoA

Question 10

citrate synthase

Answer 10

converts acetyl CoA and OAA to citrate. inhibited by high citrate concentration

Question 11

isocitrate dehydrogenase

Answer 11

converts isocitrate to alpha ketoglutarate. inhibited by ATP and NADH concentrations

Question 12

alpha ketoglutarate dehydrogenase

Answer 12

converts alpha ketoglutarate to succinyl CoA. inhibited by Succinyl CoA and NADH and ATP concentrations

Question 13

pyruvate dehydrogenase

Answer 13

converts pyruvate to acetyl CoA. very important in the brain (glucose oxidation)

Question 14

the active form of pyruvate dehydrogenase is

Answer 14

dephosphorylated

Question 15

in high ATP concentrations, PDH is

Answer 15

phosphorylated (and inacitve) to conserve the amount of ATP that needs to be made

Question 16

in low ATP concentrations, PDH is

Answer 16

DEPHOSPHORYLATED/active (activated by Ca2+) because the Ca2+ inactivates the kinase that phosphorylates PDH

Question 17

rate controlling enzymes of the TCA

Answer 17

1. citrate synthase
2. isocitrate dehydrogenase
3. alpha-ketoglutarate dehydrogenase

Question 18

oxidative phosphorylation

Answer 18

synthesis of ATP by phosphorylation of ADP. involves the ETC/ATP synthase (complex V)

Question 19

regulation of oxidative phosphorylation

Answer 19

1. substrates (NADH, O₂, ADP, succinate, P_i)
2. products (ATP, H₂O, electrochemical gradient)
3. product utilization
4. intramitochondrial ATP/ADP ratio (high ratio inhibits oxidative phosphorylation as ATP allosterically binds to Complex IV)

Question 20

electron transport is highly coupled to

Answer 20

oxidative phosphorylation

Question 21

the slowest (rate limiting) step of TCA is

Answer 21

isocitrate dehydrogenase