Kaplan Biochemistry: Chapter 10 Carbohydrate Metabolism II

Question 1

in AA catabolism, how do AA lose their amino group

Answer 1

via transamination.

Question 2

net result of citric acid cycle

Answer 2

1) Pyr dehydrogenase complex: 1 NADH
2) TCA: 3 NADH, 1 FADH2, 1 GTP.

net: 25 ATP/glc.
- then, glycolysis yields 2 atp and 2 NADH.
therefore, in total, 1 glucose = 30-32 ATP.

Question 3

name the steps of krebs

Answer 3

1) acetyl coA + OAA = citrate
2) citrate to isocitrate
3) isocitrate to alpha ketoglu. FORMS NADH
4) Alphaketoglutarate to SuccinylcoA. FORMS NADH
5) succ-coA to succinate. FORMS GTP.
6) succinate to fumarate. FORMS FADH2
7) fumarate to malate.
8) malate to OAA. FORMS NADH.

Question 4

what reaction does citrate synthase catalase

Answer 4

formation of citrate from OAA and acetyl coA.

Question 5

what reaction does isocitrate dehydrogenase catalyze

Answer 5

isocitrate to alpha ketoglutarate. FORMS NADH

Question 6

what reaction does alphaketoglutarate dehydrogenase catalyze

Answer 6

alpha keto glu to succinyl coA. Forms NADH.

Question 7

NADH that is generated by glycolysis in the cytosol cannot donate their electrons to the ETC directly because they cannot directly cross into the mitochondrial matrix. how does glycolytic NADH donate its electrons?

Answer 7

via shuttle systems;

1) glycerol 3 phosphate shuttle. loses some energy in the process because the cytosolic NADH is converted to FADH2.
2) malate aspartate shuttle. Cytosolic OAA, whcih cannot pass through the inner mito membrane can be reduced to malate, which can, using NADH. once in the mito, the reaction is reversed, NADH and OAA are recretated. NADH’s are passed to complex I. therefore, no energy release in this shuttle system.

Question 8

which ETC membrane protein is a functional enzyme in the krebs cycle

Answer 8

complex 2. its actually succinate dehydrogenase.

Question 9

____ ____ allows the chemical energy of the proton gradient to be harnessed as a means of phosphorylating ADP

Answer 9

chemiosmotic coupling

Question 10

roles of the F0 and F1 portions of ATP synthase ion channel

Answer 10

F0 portion functions as an ion channel, so protons travel thrgouh the F0 along their gradient back to the matrix

F1 portion functions as the synthase portion and uses the energy from the gradient to phosphorylate ADP to ATP.

Question 11

what is the proton motive force

Answer 11

an electrochemical gradient that stores potential energy as a result of protons being pumped out of the mitochondria into the inter membrane space as e- are shuttled throguh the chain.