Regulation of Energy

Question 1

What are metabolic pathways?

Answer 1

pathway involving multiple enzyme catalized steps
allows efficient energy utilization

pathways are interconnected

Question 2

How is flux through a pathway controlled?

Answer 2

enzymes in the pathway
supply of starting material
how much prrodcut is produced and how quickly it is being utilized

Question 3

How is flux regulated

Answer 3

Flux through a pathway is never faster than the slowest step

the rate-limiting pathway is the slowest step

Question 4

How are irreversible reactions enzyme regulated?

Answer 4

allosteric enzymes
ffedback - product inhibit
feed foward regulation
enzyme levels

Question 5

How are irreversible reactions enzyme regulated?

Answer 5

allosteric enzymes
ffedback - product inhibit
feed foward regulation
enzyme levels

Question 6

what is the substrate of TCA

Answer 6

acetl coA

Question 7

What are the products of TCA cycle

Answer 7

NADH/ FADH2, electrons , ATP

Question 8

is The TCA hormone regulated or allosterically regulated

Answer 8

not hormonal but allosterically regulated

Question 9

What dirves the TCA

Answer 9

substrate availibit nad product utilixation

Question 10

How is the TCA regulated

site 1

Answer 10

site 1
Acetyl coa + pxaloacetate –> citrate
enzyme: citrate synthase
inhibited by succinyl CCoA (only in bacteria) and citrate glutarate
enxyme isocitrate dehydrogenase
inhibited by aTP & NADH
if there is enough ATP, citrate is converted to fatty acid

Question 11

How is TCA regulated site 2

Answer 11

isocitrate __> a-ketoglutarate
enzyme: isocitrae dehydrogenase
inhibited by aTP ( acts as an allosteric regulatir) NADH
stimulated bu ADP and NAD=

this is a rate limitng step

Question 12

How is TCA regulated site 3

Answer 12

a-ketoglutarate –> succinyl coA

Enzyme: a-ketoglutarate dehydrogenase
similar to pyruvate dehydrogenase

Question 13

Substrate availability for TCA

Answer 13

Acetyl-CoA and Oxaloacetate

Question 14

How is oxidative phosphorylation regulated

Answer 14

Availibiltiy of starting materials
Product utilization
Intramitochondrial ratio ATP/ADP is a control mechanism
High ATP/ADP ratio inhibits oxidative phosphorylation
(ATP can inhibity complex 4)

Question 15

Refulation of oxidative phosphorylation

Answer 15

electorn transport is tightly coupled to oxidative phosphorylation
ADP must be aailable for oxygen to be consumed
in the abscence of ADP, aTP synthse does not consume theH+ gradient
avoid waste of fuel
availability of ADP and P1,, regulates respiratory control

Question 16

Which of the following conditions will cuase an increase in Pyruvate Dehydrogenase activity

increased phosphorylation of enzyme

increase in Ca++ levels
Increae in acetyl CoA
Increase in NADH

Answer 16

Increase in Ca++ levels

pic on phone

Question 17

During exercise, stimulation of the TCA cycle results primarrily form whichof hre folowing

allosteruc activation of isocitrate dehydrogenase by increased nadh

alosteric activation of fumurase by increased adp

procduct inhibition of citryate synthase
stimulation of flux through a number of enzymes by a decreased nadh/nad+ ratio

Answer 17

4