exam 5

Question 1

what is the committed step of purine biosynthesis

Answer 1

PRPP to 5 phospho-B-D-ribosylamine
PRPP glutamyl transferase
amido transferase

Question 2

how is the committed step of purine biosynthesis regulated

Answer 2

positive = PRPP
negative = product inhibion like IMP,GMP, AMP

Question 3

for the committed step of purine biosynthesis how does alpha of ribosyl get inverted to beta

Answer 3

Mechanism is SN2 so the nucleophine (amino group)must attack at the opposite face of the leaving group resulting in a switch from alpha to Beta

Question 4

why is ATP not required in committed step of purine biosynthesis

Answer 4

no activated intermediate because we have a good leaving group

Question 5

drug inhibits adenylate cyclase which makes cAMP

2 groups one with and wihtout drug and both no food for 8 hours who has lower blood glucose

Answer 5

drug treated

Question 6

drug inhibits adenylate cyclase which makes cAMP

2 groups one with and wihtout drug and both no food for 8 hours upon what organ is the drug accting

Answer 6

liver

Question 7

drug inhibits adenylate cyclase which makes cAMP
2 groups one with and wihtout drug and both no food for 8 hours
pathway of organ, treatment alteration, downstream effect

Answer 7

inhibits the activation of glycogen breakdown by inhibiting adenylate cyclase
usually when fasting glucagon ->activated g protein to activated adenylate cyclase (drug inhibition here) to increased cAMP to activated pKA which will both phosphorylate phosphoylase kinase to phosphoyrlate phosphoyrlase to activate glycogen break down and phosphorylate glycoge synthase to inactivate it
so the drug blocks the downstream effect of inhibiting glycogen synthase and activating glycogen phosphorylase
HOW DOES THIS REDUCE BLOOD GLUCOSE

Question 8

role of malate/aspartate shuttle

Answer 8

restores NADplus to the cytosol

Question 9

is the malate/aspartate shutttle more impoortant for aerobic or anarobic conditions

Answer 9

aerobic conditions because in anaerobic conditions the conversion of pyruvate to lactate maintains NADplus in cytosal for glycolysis to continue

Question 10

reciperocal regulated

Answer 10

one path is inhibited while other is activated

Question 11

why RR glycolysis and gluconeogensisis

Answer 11

GLycolysis generates energy but gluconeogenisis requires energy so it would be wasteful to use simultaneously

Question 12

signal for RR glycolysis and gluconeogenesis

Answer 12

F-2-6-BP activates glycolysis by stimulateing PFK1 activiety to increase conversion of f6P to F16B2
F26BP inhibits gluconeogenisis by negatively regulating F16BP which inhibits the conversion of F16BP to F6P

Question 13

pyruvate dehydrogenase consists of a highly organized supramolecular complex containgig multiple copies of each of three enYems that are arranged with one type in aninteral cluster with two types in oustide clusters

Answer 13

true
composed of 3 enzymes E1-3
E1 and E3 are outside so they can pick up substrate (pyruvate) and release products(acetylu CoA, CO2 and NADH)

Question 14

coenzyme co-substrates that are non-covalently attatched to pyruvate dehydrogenase include NAD+ and Coenzyme A

Answer 14

NAD+ = E3 co-enzyme cosubstrate and Coa = E2 co co

TPP for E1 and lipoamide for E2 and FAD for e3 are all prosthetic groups

Question 15

NADH but not acetyl CoA is a competitive and an allosteric regulator of specific enYmes fo rPDH supramolecular complex

Answer 15

false

acetyl CoA is a negative regulator of PDH

Question 16

all steps of TCA are energetically favorable

Answer 16

false

only a few steps are E favorable but have large enough -deltaG to push the cycle forward

Question 17

coordinated allosteric regulation of TCA cycle by ADP and ATP occur at specific enzymatic steps, in which neither of these molecules resemble eihter the substrate or producet

Answer 17

ture

ATP and ADP are allostereic regulators of the TCA cycle enyzyme IDH

Question 18

the electron transport chain provides 2 specific substrates for TCA

Answer 18

true

NAD+ and FAD

Question 19

Assymetrically oriented (anisotorpic localization of COmplexes I-IV in mitochondrial is not importatnt for oxidative phospohyorlation

Answer 19

false
assymetric orientation of complexes is imiportant to ensure H+ being pumped in same direction (to inner membrane) for each complex

Question 20

Complexes I-IV are separable sucha that each can function independently of each other but some of these complexes can also be found associated together suggesting higher level of organization of ETC system

Answer 20

true

III-IV complexe demonstrated

Question 21

the electrochemical gradient formed by the electron transport chain is necesssary to drive the binding change mechanism of ATP syntessis in oxidative phosphorylateion

Answer 21

true
movement of H+ down its gradient establishe dby ETC provides energy for ATP synthesis
c irng to delta to beta?

Question 22

a myocardial infarction is known to cause a decrease in the suply of oxygen to circulation and ultimatly mitochondria
what are the impacts

Answer 22

decrease in rate of ATP synthase
increase the rate of proton pumpin gcomplex IV
because the reduction of O2 is the final step in the ETC, so teh ETC (and thus rate of H+ pumping) will decrease
ATP syntheiss is couple to the ETC so it will decrease too

Question 23

P:O ratio

Answer 23

close to 3 when NADH is electron source for ETC
refers to the moles of ATP produced per .5 moles of O2 reducted by C IV using electron frsom either FADH2 or NADH
it depends on the difference in oxidation-reduction potential and intial electron donor and ultimate electron acceptor in ETC
the P:O ratio describes the relationship between moles of ATP produce and half moles of O 2 reduced
it is 3 for NADH but 1.8 for FADH2 because it bypasses C I

Question 24

protein component of ATP synthasome
where
how many
binding to proton from the gradient produced by ETC

Answer 24

C-ring subunit of FO domain

located in inner membrane, 1 c ring w/ 10-14 subunits

Question 25

protein component of ATP synthasome
where
how many
catalytic conversion to form ATP

Answer 25

Beta subunits of F1 domain

in mitochondrial matrix, 3B subunits contribute to alpha3beta3 hexamer ring of F1 domain

Question 26

protein component of ATP synthasome
where
how many
conformational changes in the binding change model of oxidative phosphorylation

Answer 26

the movement of c righ tand gamma subunit from proton flow induce conformational changes of B subunits allowing them to release ATP

Question 27

protein component of ATP synthasome
where
how many
providing half channels for proton flow from cytosol ot matrix

Answer 27

symporter= associated with C firng Fo subunit on inner membrane for H+ and Pi
or gamma subunit of ATP synthase which is in the matix
subunit a/IMM/I

Question 28

what is the committed step of pyrmidine biosynthesis

Answer 28

CAP to CAA

Question 29

how is the comitted step of pyrimidine biosyntheiss regulated

Answer 29

positive: PRPP
Negative: UMP

Question 30

role of ATP in pyrimidine biosynthesis

Answer 30

activated intermdieate for Nuc attack

Question 31

what is the major difference between the de novo pyrimidine and purine biosynthesis

Answer 31

pyrimidie is ring first and then sugar