Exam 3 (Lectures 20-23)

Question 1

What are the 3 modes of regulation?

Answer 1

Availability of substrate

Product Inhibition

Competitive feedback by downstream intermediates

Question 2

What is the purpose of TCA / Citric Acid / Krebs Cycle

Answer 2

to produce energy and building blocks (anabolic precursors)

Question 3

What are the primary reactions in TCA / Citric Acid / Krebs Cycle?

Answer 3

Oxidation and Oxidative Decarboxylation

Question 4

What are the reducing equivalents formed in TCA / Citric Acid / Krebs Cycle?

Answer 4

3 NADH

1 FADH₂

1 GTP

Question 5

Citrate Synthase

Answer 5

dimer(each monomer has small and large domain)

oxaloacetate binds first that forms the Acetyl CoA binding pocket

Question 6

Roles of Citrate in Metabolism

Answer 6

Intermedate in the TCA cycle (in mitochondria)

Activator of Fatty Acid Synthesis

Precursor of Cytoplasmic Acetyl CoA

Inhibitor of PFK1 (in cytoplasm)

Question 7

Why is there 2 parts of isomerization in Reaction 2 of TCA Cycle?

Answer 7

to put the OH group in a better position for oxidation and CO₂ release in the next step

Question 8

Reaction 3 Regulation

Answer 8

rate limiting, sets the pace of TCA

Positive Regulation: ADP, NAD⁺, Mg⁺² (Low energy conditions)

Negative Regulation: NADH and ATP (High energy conditions)

Question 9

Whenever there is CoA, the next reaction is going to be?

Answer 9

a huge to do something big…

Question 10

Reaction 4 Regulation

Answer 10

Negative Regulation: down regulated by ATP and product inhibition through NADH and Succinyl CoA

(High energy and product inhibition)

Question 11

What powers the synthesis of GTP?

Answer 11

the release of CoA

Question 12

Reaction 6 Regulation

Answer 12

Negative: FADH₂ / FAD

Question 13

Flavin ring in Succinate Dehydrogenase

Answer 13

is covalently attached

is imbedded in the inner mitochondrial membrane

is also part of the electron transport chain

Question 14

Reaction 8 Regulation

Answer 14

Negative: high NADH / NAD⁺ ratio

Question 15

Pyruvate to Acetyl CoA Regulation

Answer 15

High levels of ATP, acetyl CoA, and NADH = inhibition

Low energy and high conc of substrate will activate the complex (ADP and Pyruvate)

Question 16

What is another way Citrate is used for?

Answer 16

to make fatter acids and sterols

Question 17

What is another way α-Ketoglutarate used for?

Answer 17

to make Glutamate, other amino acids, and purines

Question 18

What is another way Succinyl CoA is used for?

Answer 18

to make Porphyrins, heme, and chlorphyll

Question 19

What is another way Oxaloacetate is used for?

Answer 19

to make Asparate, other amino acids, purines, and pyrimidines

Question 20

Quantifying Electron Transfer Potential

Answer 20

ΔG^o’ = - nFΔE’₀

n = number of electrons

F = farraday’s constant (96.48 kJ/molV)

ΔE’₀ = reduction potential

Question 21

The more negative E is..

Answer 21

the greater the tendency to donate electrons

Question 22

Chemiosmotic Potential

Answer 22

causes protons to flow back into the mitochondrial matrix that turns the turbine-like molecular motor which helps to synthesize ATP

Question 23

What are the rotating components in the ATP Synthase?

Answer 23

c ring, gamma, and the epsilon

Question 24

What are the stationary components of ATP Synthase?

Answer 24

Stator: a, b₂, delta

Hexameric Ring: alpha₃ and beta₃

Question 25

UCP-1 Regulation

Answer 25

in the body's respond to cold, fatty acids will be broken down that upregulates UCP-1

Question 26

What is 2,4-Dinitrophenol (DNP)?

Answer 26

a small compound in the production of TNT takes protons directly from the intermembrane space to the matrix bypassing ATP synthase Symptoms: high temp and lack of energy

Question 27

What poison blocks Complex I?

Answer 27

Rotenone - insecticide Amytal - barbituate

Question 28

What poison blocks Complex III?

Answer 28

Antimycin A - antibiotic

Question 29

What poison blocks Complex IV?

Answer 29

CN^- H₂S - sewer gas CO

Question 30

What poison blocks ATP Synthase?

Answer 30

Oligomycin

Question 31

What happens when the poisons block the complexes?

Answer 31

Oxygen consumption by the mitochonrion will go down

Question 32

What happens when the poison blocks ATP Synthase?

Answer 32

Oxygen consumption remains the same for a while until the concentration of protons will be so great that the complexes will no longer be able to move protons against the gradient

Question 33

For NADH and FADH₂ that enters the ETC, how many moles of ATP is produced?

Answer 33

1 NADH ≈ 2.5 mol ATP 1 FADH₂ ≈ 1.5 mol ATP

Question 34

What is the net molecules of ATP from Glycolysis?

Answer 34

2 ATP per molecule of glucose

Question 35

What is the net molecule of ATP from TCA cycle?

Answer 35

2 ATP per molecule of glucose

Question 36

Net Yield per molecule of Glucose?

Answer 36

Glycerol 3-P: 30 ATP Malate-Asparate: 32 ATP

Question 37

Ends of Glycogen are...

Answer 37

non-reducing

Question 38

What are the primary storage sites for Glycogen?

Answer 38

skeletal muscles (2% by wt) and liver (10% by wt) stored as granules in the cytoplasm

Question 39

What does Glycogen Phosphorylase do to glycogen?

Answer 39

cleaves glucose through add of inorganic phosphate phosphorylytic not hydrolytic reaction

Question 40

Pyrifoxal Phosphate

Answer 40

cofactor of Glycogen Phosphorylase and a B vitamin derivative acts as an acid-base catalyst

Question 41

What are the two functions of the Debranching enzymes?

Answer 41

tranferase (transfers the remaining 3 glucose cell units to the end of a straight chain) alpha-1,6-glucosidase (hydrolizes glucose from the branch point)

Question 42

What is the use of hexokinase in glycogen degredation?

Answer 42

to phosphorylate the freed glucose from the debranching enzyme so it stays in the cell and not leave through diffusion

Question 43

Glycogen phosphorylase cannot attack glucose cell residues that are any closer than...

Answer 43

4 residues away from an alpha 1,6 linkage branch point

Question 44

Glycogenin

Answer 44

a dimeric protein with alpha-1,4 linked oligosaccharides used as a primer to initiate synthesis of new glycogen molecule

Question 45

Glycogen Phosphorylase Regulation

Answer 45

has a tense and relaxed state where tense state is when the active site is partially blocked Phosphorylase a is when enzymes are phosphorylated Phosphorylase b is when enzymes are not phophorylated

Question 46

Phosphorylase a favors what state?

Answer 46

relaxed state and therefore more active

Question 47

Phosphorylase b is most often in what state?

Answer 47

tense state

Question 48

What is activated by epinephrine in the liver?

Answer 48

beta and alpha adrenergic receptors

Question 49

In muscles, high levels of AMP and low energy can cause..

Answer 49

AMP to bind to phosphorylase b's nucleotide binding site and causes it to favor the relaxed state

Question 50

In liver, high levels of glucose can cause...

Answer 50

glucose to bind to phosphorylase a's regulatory site favoring the tense state