MBC: Cell metabolism: 3 fates of pyruvate

Question 1

3 fates of pyruvate?

Answer 1

alcohol fermentation
lactate fermentation
acetyl CoA production (Link reaction)

Question 2

Alcohol fermentation reactions, enzymes involved, type of reaction?

Overall reaction?

Answer 2

i) pyruvate+ H+ –> ethanal +CO2

pyruvate decarboxylase enzyme

decarboxylation reaction

ii) ethanal + H+ –> ethanol

NADH oxidised to NAD+

alcohol dehydrogenase enzyme

reduction reaction

overall:
Glucose+ 2Pi+ 2ADP+ 2H+ –> 2ethanol+ 2CO2 +2 ATP + 2H2O

Question 3

Lactate fermentation reactions, enzymes involved, type of reaction?

When would this reaction take place?

Overall reaction?

Answer 3

pyruvate + 2H+ –> lactate
NADH–> NAD+

lactate dehydrogenase

reduction reaction

occurs when oxygen limiting factor

overall:
glucose+2Pi+ 2 ADP–> 2Lactate+ 2ATP+ 2H2O

Question 4

regeneration of NAD+ occurs in both of these pathways, why is it important?

Answer 4

allows continuation of glycolysis under oxygen deprivation

Question 5

Creatine phosphate function? Reaction? enzymes involved?

Answer 5

creatine phosphate +H+–> creatine+ ATP

Creatine Kinase enzyme

creatine acts as a buffer to provide phosphate for the phosphorylation of ADP to ATP

Question 6

Acetyl CoA production reactions, enzymes involved?

Answer 6

pyruvate+ HS-CoA+ NAD+ –> Acetyle CoA +CO2+ NADH
NAD–> NADH

pyruvate dehydrogenase enzyme complex

Question 7

importance of thiamine? Consequences of thiamine deficiency?

Answer 7

Thiamine is a cofactor of pyruvate dehydrogenase complex (PDH)

Deficiency of thiamine causes Beri-Beri