TCA Cycle

Question 1

Acetyl CoA pushed through the TCA cycle, how much of the following molecules are produced:

Answer 1

3 NADH (2.5)
1 FADH2 (1.5)
1 GTP
2 CO2

Question 2

How much ATP is produced per Acetyl CoA pushed in the TCA cycle?

Answer 2

10 ATP equivalents

Question 3

What reaction does citrate synthase catalyze?

Answer 3

OAA + Acetyl CoA–> Citrate

Question 4

The presence of what molecule inhibits citrate synthase?

Answer 4

citrate (-)

Question 5

What reaction does isocitrate dehydrogenase catalyze?

Answer 5

Isocitrate + NAD+ –> alpha-ketoglutarate + CO2 + NADH

Question 6

What molecules inhibit isocitrate dehydrogenase?

Answer 6

ATP (-)

NADH (-)

Question 7

The presence of what molecule activates isocitrate dehydrogenase?

Answer 7

ADP (+)

Ca2+ (+) muscle

Question 8

What enzyme catalyzes the formation of succinyl CoA from alpha- ketoglutarate?

Answer 8

alpha-ketoglutarate dehydrogenase

Question 9

formation of succinyl CoA also releases what molecules?

Answer 9

NADH
CO2
Step 4

Question 10

What molecules inhibit the enzyme

Answer 10

succinyl CoA
NADH(-)
ATP (-)
Ca2+ (+)

Question 11

formation of what molecule in the TCA cycle results in GTP liberation

Answer 11

Succinate
via succinyl-CoA synthetase
STep 5

Question 12

formation of what molecule in the TCA cycle results in FADH2 liberation

Answer 12

Fumarate
via succinate dehydrogenase
Step 6

Question 13

What reaction does malate dehydrogenase catalyze?

Answer 13

malate + NAD+ –> OAA + NADH

Step 8

Question 14

Is the reaction that malate dehydrogenase catalyzes reversible

Answer 14

Yes important in gluconeogenesis

Question 15

Pyruvate Dehydrogenase Complex Rxn

Answer 15

Pyruvate –> Acetyl CoA + CO2

produces NADH

Question 16

Pyruvate Dehydrogenase complex uses cofactors

Answer 16

Thiamine
Lipoate
FAD 
NAD+
Coenzyme A

Question 17

Pyruvate Dehydrogenase Complex has 3 catalytic subunits

Answer 17

E1- coenzyme TPP
E2- coenzyme LIpoate
E3- coezyme FAD

Question 18

E1 subunit of PDC rxn

Answer 18

pyruvate is decarboxylated and attached to TPP

Question 19

E2 subunit of PDC rxn

Answer 19

hydroxyethyl gorup is oxidized and transferred to Lipoate

acetyl gorup is transferred to CoA

Question 20

E3 subunit of PDC rxn

Answer 20

sulfhydryl lipoate is deoxidized using FAD and NAD+

to regenerate E2

Question 21

vitamin for Thiamine Pyrophosphate (TPP)

Answer 21

thiamine (B1)

Question 22

vitamin for lipoate/lipoamide

Answer 22

fatty acid - Octanoic Acid

Question 23

vitamin for Flavin Adenin Dinucleotide (FAD)

Answer 23

riboflavin

Question 24

vitamin for Nicotinamide Adenine Dinucleotide (NAD+)

Answer 24

Niacin

Question 25

Vitamin for Coenzyme A (CoA)

Answer 25

Panthothenate

Question 26

Regulation of PDC

Answer 26

PDC kinase - inactivates PDC | PDC phosphatase - activates PDC

Question 27

PDC kinase regulation

Answer 27

NADH (+) Acetyl CoA(+) ADP (-) pyruvate (-)

Question 28

PDC phosphatase regulation

Answer 28

Ca2+ (+)

Question 29

PDC deficiency

Answer 29

pyruvate is reduced to lactic acid lactic acidemia mental retardation- brain requires glucose for energy

Question 30

TCA occurs in

Answer 30

mitochondria

Question 31

Acetyl CoA is generated from

Answer 31

``` glucose fatty acids amino acids ketone bodies acetate ```

Question 32

Acetyl CoA is oxidized to

Answer 32

CO2 | generates reducing equivalents and GTP

Question 33

TCA cycle is initiated by

Answer 33

Acetyl CoA | OAA

Question 34

TCA cycle generates _ ATP from fuel oxidation

Answer 34

2/3

Question 35

TCA intermediates are critical precursors for biosynthetic pathways

Answer 35

``` Citrate- FA synthesis alpha KG- AA synthesis, neurotransmitter Succinyl CoA- heme synthesis Malate- gluconeogenesis OAA- AA synthesis ```

Question 36

Anaplerotic reactions replenish intermediates of TCA

Answer 36

``` AA --> pyruvate --> OAA Carb, FA, AA --> Acetyl CoA--> Citrate AA--> Glutamate --> alpa -KG Val, Ile, Thr, Met--> propinoyl CoA --> Succinyl CoA AA- fumurate Aspartate--> OAA ```

Question 37

Pyruvate carboxylase

Answer 37

major anapldrotic enzyme Biotin- coenzyme that transfers the CO2 to Pyruvate to make OAA Acetyl CoA (+) liver, brain, adipocytes

Question 38

Fumarase deficiency

Answer 38

Fumarase --X--> Malate neurological disorders, encephalomyopathy evident at birth elevated elevated fumarate, succinate, alpha-KG, citrate, malate in Urine

Question 39

alpha-KG deficiency

Answer 39

oxoglutaric aciduria | infantile lactic acidosis , retardation, sudden death, myocardiopathy, hepatic disorders

Question 40

Thiamine def

Answer 40

dietary or chronic alcoholism | inhibits alpha-KG & PDC complex