Metabolic Pathways and ATP Production II

Question 1

Pyruvate dehydrogenase complex overall reaction?

Answer 1

Pyruvate + HS-CoA + NAD+ –> NADH + Acetyl CoA + CO2

Question 2

What ancestry does acetyl CoA have, DNA or RNA?

Answer 2

RNA

Question 3

How does the TCA cycle start?

Answer 3

The 2C from acetyl CoA condenses with the 4C of oxaloacetate, to give 6C citrate. Enzyme: citrate synthase

Question 4

Second step of the TCA cycle? Reactant: citrate

Answer 4

Isomerisation of citrate to isocitrate. Enzyme: aconitase

Question 5

How many reactions in the TCA cycle?

Answer 5

8

Question 6

Third step of the TCA cycle? Reactant: isocitrate

Answer 6

Isocitrate oxidised to alpha ketoglutarate. This step forms a CO2 and NADH. Enzyme: isocitrate dehydrogenase

Question 7

Fourth step of the TCA cycle? Reactant: alpha ketoglutarate

Answer 7

Alpha ketoglutarate –> succinyl-CoA. This step produces NADH and CO2. Enzyme: alpha-ketoglutarate dehydrogenase complex

Question 8

Fifth step of the TCA cycle? Reactant: succinyl-CoA

Answer 8

Succinyl-CoA has the CoA displaced to succinate. This phosphorylates a GTP. Enzyme: succinyl-CoA synthetase

Question 9

Sixth step of the TCA cycle? Reactant: succinate

Answer 9

Succinate oxidised to fumarate. FADH2 is generated.

Question 10

Seventh step of the TCA cycle? Reactant: fumarate

Answer 10

Fumarate is hydrolysed to malate. Enzyme: fumarase

Question 11

Eighth step of the TCA cycle? Reactant: malate

Answer 11

Malate dehydrogenated to reform oxaloacetate. NADH is generated. Enzyme: malate dehydrogenase

Question 12

What two uses does GTP have?

Answer 12

As a signalling molecule or can donate a phosphate group to ADP to form ATP

Question 13

How many NADH does one turn produce?

Answer 13

3

Question 14

How many GTP and ATP does one turn produce?

Answer 14

1 and 0

Question 15

How many FADH2 does one turn produce?

Answer 15

1

Question 16

How many CO2 does one turn produce?

Answer 16

2

Question 17

How many types of products does one turn produce?

Answer 17

4

Question 18

Which steps of the cycle produce NADH?

Answer 18

3, 4 and 8

Question 19

Which steps of the cycle produce FADH2?

Answer 19

6

Question 20

Which steps of the cycle produce CO2?

Answer 20

3 and 4

Question 21

Which steps of the cycle produce GTP?

Answer 21

5

Question 22

What does one turn of the TCA cycle produce overall?

Answer 22

3 NADH, 1 FADH2, 2 CO2 and 1 GTP

Question 23

Which Krebs cycle protein is not found in the mitochondrial matrix space?

Answer 23

Succinate dehydrogenase, it is an integral membrane protein

Question 24

How many molecules of ATP is produced per glucose?

Answer 24

38

Question 25

How many molecules can the degradation of the 20 amino acids give arise to?

Answer 25

7 (pyruvate, acetyl CoA, acetoacetyl CoA, alpha ketoglutarate, succinylcholine CoA, fumarate, oxaloacetate

Question 26

How is an amino acid degraded?

Answer 26

Amino acid group is removed and excreted as urea, and the carbon skeleton is funnelled into the production of glucose or the Krebs cycle

Question 27

What type of reaction does protein metabolism involve?

Answer 27

Transamination

Question 28

What is a transamination reaction?

Answer 28

The transfer of an amine group from an amino acid to a keto acid forming a new pair of amino and keto acid

Question 29

Where do transamination reactions occur?

Answer 29

In hepatic tissue

Question 30

What is hepatic tissue?

Answer 30

Tissue of the liver

Question 31

What does the transamination of alanine and alpha ketoglutarate produce?

Answer 31

Pyruvate and glutamate

Question 32

What two methods are available for NADH from glycolysis to be transported into the mitochondrial matrix?

Answer 32

Glycerol phosphate shuttle and malate aspartate shuttle

Question 33

Where does the glycerol phosphate shuttle take place?

Answer 33

Skeletal muscle and brain

Question 34

Where does the malate aspartate shuttle take place?

Answer 34

Liver, kidney, heart

Question 35

Explain the glycerol phosphate shuttle

Answer 35

NADH transfers its electrons to dihdroxyacetone phosphate (with the enzyme cytosolic glycerol-3-phosphate dehydrogenase) to form glycerol 3 phosphate. Glycerol 3 phosphate then passes it to a membrane bound FAD with a membrane bound form of the same enzyme. The electrons are then passed to coenzyme Q of the ETC

Question 36

What is the net reaction of the malate aspartate shuttle?

Answer 36

NADHcyto + NAD+mito --> NAD+cyto + NADHmito

Question 37

Explain the malate aspartate shuttle

Answer 37

A hydride ion is transferred from cytoplasmic NADH to oxaloacetate to reduce it to malate (catalysed by cytosolic malate dehydrogenase MDH). Malate is transported into the mitochondria where it is reoxidised by NAD+ to give oxaloacetate and NADH (catalysed by mitochondrial MDH). Oxaloacetate is then converted into aspartate and glutamate is used to make alphaketoglutarate via a transamination reaction.

Question 38

What two uses does NADPH have?

Answer 38

Synthesis of DNA and cholesterol

Question 39

Whats the difference between NADH and NADPH?

Answer 39

A phosphate group attached to position 2 of the ribose ring