Exam Review

Question 1

in order to enter the TCA, what must energy containing nutrients be converted to ?

Answer 1

acetyl CoA

Question 2

TCA characteristics

Answer 2

aerobic metabolism

produces more nrg than glycolysis

occurs in mito

goal = make high nrg e-‘s in the form of FADH2, NADH

pyruvate dehydrogenase links glycolysis to TCA

Question 3

list the enzymes of TCA

Answer 3

1. pyruvate dehydrogenase complex
2. citrate synthetase
3. aconitase
4. isocitrate dehydrogenase*
5. a-ketoglutarate dehydrogenase complex
6. succinyl coA synthetase
7. succinate dehydrogenase
8. fumarase
9. malate dehydrogenase

Question 4

why is the TCA cycle Anaplerotic?

Answer 4

because the rxns provide intermediates to replenish TCA cycle

why TCA is tightly regulated

2 major rxns

• –degradation of AA
• –carboxylation of pyruvate

Question 5

when are TCA intermediates used in anabolic functions?

Answer 5

when nrg needs are met
intermediates for biosynthesis of other molecules are drawn away

they are returned to TCA by formation of oxaloacetate from pyruvate

Question 6

what are the 3 goals of OxPhos

Answer 6

transfer e- from NADH/FADH2 to O2

establish proton gradient

synthesize ATP

Question 7

describe the 2 phases of the PPP

Answer 7

oxidative/first phase makes NADPH

nonoxidative phase shuffles carbons to create F6P and GAP

Question 8

why do we need NADPH?

Answer 8

synthesis of monomers

reducing power for detoxification

Question 9

structure of glutathione

Answer 9

tripeptide

glutamic acid - cysteine - glycine

Question 10

G6PD regulation

Answer 10

activators:
dimerization
TF for anti-oxidant genes
cell cycle and synthesis activators
insulin

inhibitors:
phosphorylation
apoptosis signaling proteins

Question 11

list the carbon shuffles of the nonoxidative phase

Answer 11

1. ribulose-5-pi isomerization
2. transketolase transfers 2C
3. transaldolase transfers 3C
4. regeneration of G6P via gluconeogenesis

Question 12

what are the 4 modes of PPP based on cell needs?

Answer 12

1. nucleotide synthesis - ribose5P
2. ribose5P and NADPH
3. NADPH
4. energy needed = F6P and GAP to enter glycolysis

Question 13

formation of pyrimidines

Answer 13

form N base independent of PRPP

unidirectional pathway
cytoplasmic

precursors used: NH3 from Gln, Asp, HCO3

allosteric regulation:
Pyr inhibit (C)
Pur activates (A/G)

Question 14

formation of purines

Answer 14

form N base on PRPP
branched pathway
cytoplasmic
precursors: NH3 from Gln, Gly, Asp, N10-formyl-THF, HCO3

regulation:
feedback inhibition by purines

Question 15

salvage - nucleotide synthesis

Answer 15

pyrimidines:
use phosphorylases and kinases for salvage in 2 steps

purines:
use phosphoribosyltransferases to salvage in 1 step

Question 16

what can we do w/ individual AA?

Answer 16

dispose of N thru urea cycle
make new proteins
repurpose carbon skeletons

Question 17

deamination - big picture

Answer 17

separate NH3 from C(alpha)
thus leaving behind C skeleton

most AA follow a 2-enzyme mechanism

Question 18

enzymes to know – AA Catabolism

Answer 18

1. SGOT
2. SGPT
3. glutamate dehydrogenase
4. serine dehydratase
5. glutamine synthetase
6. glutaminase
7. CPS-I and urea cycle enzymes

Question 19

SGOT

Answer 19

serum glutamate-oxaloacetate transaminase

Question 20

SGPT

Answer 20

serum glutamate pyruvate transaminase

Question 21

list the ketogenic only amino acids

Answer 21

leucine

lysine

Question 22

list the glucogenic and ketogenic amino acids

Answer 22

isoleucine
phenylalanine
threonine
tryptophan 
tyrosine