Citric Acid Cycle

Question 1

Citric acid cycle produces reduced coenzymes

Answer 1

-NADH
- FADH2
- one ATP directly.

Question 2

(1-8) Reactions in citric acid cyle

Answer 2

1: Condensation
2: Isomerization
3: Oxidative decarboxylation
4: Oxidative decarboxylation
5: hydrolysis
6: dehydration
7: hydration
8: dehydrogenation

Question 3

Product in reaction 1

Answer 3

Citrate

Question 4

Product in reaction 2

Answer 4

Isocitrate

Question 5

Product in reaction 3

Answer 5

a-Ketoglutarate

Question 6

Product in reaction 4

Answer 6

Succinyl CoA, NADH

Question 7

Product in reaction 5

Answer 7

Succinate, GTP, CoA

Question 8

Product in reaction 6

Answer 8

Fumarate

Question 9

Product in reaction 7

Answer 9

Malate

Question 10

Product in reaction 8

Answer 10

Oxaloacetate

Question 11

Isomerizes to isocitrate.

Answer 11

Citrate

Question 12

Has a tertiary —OH group converted to a secondary—OH in isocitrate that can be oxidized.

Answer 12

Citrate

Question 13

Undergoes decarboxylation (carbon removed as CO2)

Answer 13

Isocitrate

Question 14

▪ Undergoes decarboxylation to form succinyl CoA.
▪ Produces a 4-carbon compound that bonds to CoA.
▪ Provides H+ and 2e−
to reduce NAD+ to NADH.

Answer 14

(alpha)a-Ketoglutarate

Question 15

Undergoes breaking of the thioester bond

Answer 15

Succinyl CoA

Question 16

Provides energy to add phosphate to GDP and form GTP, a highenergy compound.

Answer 16

Succinyl CoA

Question 17

▪ Undergoes dehydrogenation.
▪ Loses two H and forms a double bond.
▪ Provides 2H to reduce FAD to FADH2.

Answer 17

Succinate

Question 18

▪ Undergoes hydration.
▪ Adds water to the double bond.
▪ Is converted to malate

Answer 18

Fumarate

Question 19

▪ Undergoes dehydrogenation.
▪ Forms oxaloacetate with a C=O double bond.
▪ Provides 2H that reduce NAD+ to NADH + H+

Answer 19

Malate

Question 20

Products formed in one turn of the citric acid cycle

Answer 20

• 2 CO2
• 3 NADH
• 1 FADH2
• 1 GTP

Question 21

enzyme in reaction 1

Answer 21

Citrate synthase

Question 22

enzyme in reaction 2

Answer 22

Aconitase

Question 23

enzyme in reaction 3

Answer 23

Isocitrate dehydrogenase

Question 24

enzyme in reaction 4

Answer 24

a-ketoglutarate dehydrogenase

Question 25

enzyme in reaction 5

Answer 25

Succinyl-CoA synthetase

Question 26

enzyme in reaction 6

Answer 26

Succinic dehydrogenase

Question 27

enzyme in reaction 7

Answer 27

Fumarase

Question 28

enzyme in reaction 8

Answer 28

Malate dehydrogenase

Question 29

The reaction rate for citrict acid cycle: Increases when low levels of ____ or ____ activate ______ ______.

Answer 29

- ATP or NAD+ - isocitrate dehydrogenase.

Question 30

Decreases when high levels of ___ __ ___ inhibit ____ _____ (first step in cycle).

Answer 30

- ATP or NADH - citrate synthetase