01b: PDH, TCA Cycle, Urea Cycle Flashcards

1
Q

Overall PDH rxn: what goes in?

A

Pyruvate, NAD, CoA

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2
Q

Overall PDH rxn: what comes out?

A

Acetyl-CoA, CO2, NADH

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3
Q

PDH: (oxidation/reduction) must occur to produce acetyl-CoA. Otherwise, (carboxylation/decarboxylation) will produce a(n) (X).

A

Oxidation (thus, NAD reduction);
Decarboxylation;
X = acetyladehyde

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4
Q

Dehydrogenation is essentially (oxidation/reduction)

A

Oxidation

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5
Q

List the three components of PDH and their cofactors.

A
  1. PDH (ft. TPP)
  2. Dihydrolipoyl transacetylase (ft. Lipoic acid)
  3. Dihydrolipoyl dehydrogenase (ft. FAD)
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6
Q

Vit B1 is (X), B2 is (Y). Which cofactor is each important for?

A
X = thiamine (TPP)
Y = riboflavin (FAD)
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7
Q

Lipoic acid is cofactor for (X) of PDH complex. It attaches to (Y) residue of (X).

A
X = Dihydrolipoyl transacetylase;
Y = lysine
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8
Q

E3 of PDH complex is important for regenerating (lipoic/dihydrolipoic) acid from (lipoic/dihydrolipoic) acid. Star the reduced form of the compound and state whether this reaction is an oxidation or reduction.

A

Lipoic;
Dihydrolipoic*

(Thus, this is an oxidation reaction)

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9
Q

E3 has to (oxidize/reduce) (X) to regenerate (lipoic/dihydrolipoic) acid.

A

Reduce;
X = FAD
Lipoic

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10
Q

(X) component of PDH (oxidizes/reduces) (FAD/FADH2) via (oxidation/reduction) of (NAD/NADH).

A
X = E3 (dihydrolipoyl dehydrogenase);
Oxidizes FADH2 (back to FAD);
Reduction of NAD
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11
Q

T/F: Acetyl-CoA cannot be converted back to glucose.

A

True (hence importance of PDH regulation)

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12
Q

High values for which ratios inhibit PDH?

A
  1. Acetyl-CoA:CoA

2. NADH:NAD

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13
Q

High values for which ratios activate PDH kinase, thus (activating/inhibiting) PDH?

A

Inhibiting;

  1. Acetyl-CoA:CoA
  2. NADH:NAD
  3. ATP/ADP
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14
Q

PDH Phosphatase is activated by (X), which then are indirect (stimulators/inhibitors) for PDH.

A

Stimulators;

X = Insulin, Pyruvate, Ca

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15
Q

How would you expect PDH deficiency to impact lactate levels? Pyruvate?

A

Both elevated

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16
Q

PDH deficiency is commonly inherited/transmitted in (X) manner. It may result in death of newborn due to severe (Y)

A
X = X-linked
Y = lactic acidosis
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17
Q

The fundamental issue in PDH deficiency is one of (synthesis/degradation/transport).

A

Transport of E1a into mitochondria

18
Q

TCA Cycle (uses/produces) (X) molecules of CO2 per cycle.

A

Produces;

X = 2

19
Q

TCA Cycle produces (X) NADH and (Y) FADH2 and (Z) ATP.

A

X = 3
Y = 1
No ATP, but 1 GTP

20
Q

Production of (X) in TCA Cycle is example of substrate level phosphorylation.

A

X = GTP

21
Q

(X) component of TCA Cycle can branch off and become Phosphoenolpyruvate, which can enter (Y) reaction.

A
X = oxaloacetate;
Y = gluconeogenesis
22
Q

FA synthesis can occur when (X) component of TCA Cycle becomes (Y) compound.

A
X = citrate (exits to cytoplasm);
Y = acetyl-coa (by releasing oxaloacetate FYI)
23
Q

(X) enzyme of TCA Cycle is similar to PDH in structure/cofactors, but differs in which regulation mechanism?

A

X = alpha-ketoglutarate dehydrogenase;

Not regulated by phosphorylation

24
Q

List the enzymes in TCA cycle that carry out reduction of NAD.

A
  1. Isocitrate dehydrogenase
  2. Alpha-ketoglutarate dehydrogenase
  3. Malate dehydrogenase
25
Q

Succinyl-CoA inhibits (X) enzyme of TCA Cycle.

A

X = Alpha-ketoglutarate dehydrogenase

26
Q

Arsenic poisoning is a reaction with (X), which (stimulates/inhibits) (Y) key enzymes.

A

X = lipoic acid
Inhibits;
Y = PDH and Alpha-ketoglutarate dehydrogenase

27
Q

Isocitrate dehydrogenase enzymes differ in their (oxidation/reduction) of (X).

A

Reduction;

X = NAD or NADP

28
Q

Mutations in (X) isozymes of isocitrate dehydrogenase result in (loss/gain) of function.

A

X = IDH1 or IDH2

Gain (oncogenic mutations)

29
Q

Two major systems for degrading proteins are:

A
  1. Lysosomes

2. Ubiquitin-proteosome

30
Q

The toxic byproduct of AA metabolism is (X). (Y) organ takes care of this by converting it to (Z).

A
X = Free ammonia
Y = liver
Z = non-toxic urea
31
Q

List the enzymes of the urea cycle in order of action. Star the ones in the cytosol. Where are the others?

A
  1. Carbamoyl-P Synthetase
  2. Ornithine transcarbamoylase
  3. Argininosuccinate synthetase*
  4. Argininosuccinase*
  5. Arginase*

Mitochondrial matrix

32
Q

In urea cycle, (X) is transported out of mito in exchange for (Y) coming in.

A
X = citrulline
Y = ornithine
33
Q

The importance for compartmentation of (X) enzymes in urea cycle is that (Y) is also an intermediate for (Z) pathway.

A
X = Carbamoyl-P synthetase and ornithine transcarbamoylase
Y = carbamoyl-P
Z = pyrimidine biosynthesis (in cytoplasm)
34
Q

The two forms of (X) enzyme are important control points for urea cycle and pyrimidine biosynthesis. Which reaction/enzyme is compartmentalized in mito?

A

X = carbamoyl-P synthetase (1 and 2)

Carbamoyl-P synthetase 1 (for urea cycle)

35
Q

A total of (X) ATP are (produced/used) by one round of urea cycle. How many ADP/AMP are (used/produced)

A

X = 3

2 ADP, 1 AMP produced

36
Q

Big picture: what are the components that go into urea cycle?

A

CO2, NH4, 3 ATP, Asp, 2 H2O

37
Q

Big picture: what are the products of the urea cycle?

A

Urea, 2 ADP, 2 Pi, AMP, PPi, fumarate

38
Q

(Asp/fumarate) is needed for the urea cycle. Then, (X) enzyme produces (asp/fumarate) when (Y) is produced.

A

Asp;
X = argininosuccinase
Fumarate
Y = arginine

39
Q

TCA Cycle enzymes are important for urea cycle in conversion/recycling of (X) to (Y).

A
X = fumarate
Y = aspartate
40
Q

Excess nitrogen from the metabolism of amino acids in muscle is largely transferred to the liver in the form of:

A

Alanine