TCA cycle

Question 1

How many reactions does the TCA cycle have

Answer 1

8

Question 2

Give an overview of the TCA cycle

Answer 2

2 carbon unit (from acetyl coenzyme a) condenses with a four-carbon unit

resulting 6 carbon unit is decarboxylated twice - yields co2

4 oxidation reactions yields NADH + H+ and FADH2

1 GTP is formed - substrate-level phosphorylation

the 4 carbon unit is recreated

Question 3

where is pyruvate actively transported into

Answer 3

the mitochondrial matrix, where it is oxidised and the citric acid cycle occurs

Question 4

what is pyruvate oxidized into

Answer 4

acetate, with the formation of NADH and the release of CO2; acetate is combined with coenzyme A, yielding acetyl co enzyme a

Question 5

what is the first step of the TCA cycle

Answer 5

the 2-carbon acetyl group and 4-carbon oxaloacetate combine forming 6-carbon citrate

Question 6

what is the second step of the TCA cycle

Answer 6

citrate is rearranged to form its isomer isocitrate

Question 7

what is the third step of the TCA cycle

Answer 7

isocitrate is oxidized to alpha-ketoglutarate, yielding NADH and CO2

Question 8

what is the fourth step of the TCA cycle

Answer 8

alpha-ketoglutarate is oxidized to succinyl CoA with the formation of NADH and CO2; this step is almost identical to pyruvate oxidation

Question 9

what is the fifth step of the TCA cycle

Answer 9

Succinyl CoA releases coenzyme A, becoming succinate; the energy thus released converts GDP to GTP which in turn converts ADP to ATP

Question 10

what is the sixth step of the TCA cycle

Answer 10

succinate is oxidized to fumarate, with the formation of FADH2

Question 11

what is the seventh step of the TCA cycle

Answer 11

fumarate and water react, forming malate

Question 12

what is the eighth step of the TCA cycle

Answer 12

malate is oxidized to oxaloacetate, with the formation of NADH, Oxaloacetate can now react with acetyl CoA to reenter the cycle

Question 13

what are the 9 substances in the TCA cycle

Answer 13

Acetyl Coenzyme A
Citrate
Isocitrate
alpha-ketoglutarate
succinyl CoA
succinate
fumarate
malate
oxaloacetate

Question 14

Citrate synthase

Answer 14

Acetyl CoA + Oxaloacetate -> Citrate + CoA

Question 15

Aconitase

Answer 15

Citrate–> Isocitrate

Question 16

Isocitrate dehydrogenase

Answer 16

Isocitrate + NAD+ —> a-ketoglutarate + NADH +CO2

Question 17

a-ketoglutarate dehydrogenase

Answer 17

a-ketoglutarate + NAD+ +CoA —> succinyl CoA + NAD H +CO2

Question 18

succinyl thiokinase (doesn’t follow the rule, odd one out)

Answer 18

Succinyl CoA + GDP + Pi —> Succinate CoA + NAD H +CO2

Question 19

succinate dehydrogenase

Answer 19

succinate + FAD —> fumarate + FADH2

Question 20

fumarase

Answer 20

fumarate + H2O —> Malate

Question 21

malate dehydrogenase

Answer 21

malate + NAD+ —> oxaloacetate + NADH

Question 22

what is the only enzyme of the TCA cycle that isn’t located in the mitochondrial matrix

Answer 22

succinate dehydrogenase
is integrated in the inner mitochondrial membrane
part of the complex II of the electron transport chain

Question 23

in what form are two carbon atoms released from the TCA cycle

Answer 23

CO2, and the TCA cycle gains two carbons in the form of acetyl coenzyme A

Question 24

how are electrons transferred in the TCA cycle

Answer 24

3 pairs of electrons to NAD+ to form NADH + H+, and the transfer of 1 pair of electrons to reduce FAD to FADH2

Question 25

how does the cycle get energy

Answer 25

high ATP, NADH and acetyl CoA