Question

In the Cori cycle, when glucose is degraded by glycolysis to lactate in muscle, the lactate is excreted into the blood and returns to the liver. In the liver, lactate is converted back into glucose by gluconeogenesis. For each given enzyme, identify whether it is involved in the glycolysis pathyway, gluconeogenesis pathway, both pathways, or neither pathway.

Answer 1

Answer: Cori cycle  consumes more energy,it expended 4ATPs, therefore with poor efficiency.

1 Glyceraldehyde 3-phosphate dehydrogenase.

it is an enzyme which  functions in Glycolysis only, to breakdown the 6th. step of of subtrate phosphorylation of glucose.

2. glucose-6-phosphotase.

This is the enzyme that works in gluconeogenesis only to intiaate its  first step. it hydrolyse glucose-6-phosphate , to generate glucose and phosphate.

Alcohol dehydrogenase

This enzyme does not play any role with both pathways.Rather it catalysis the oxidation of primary and secondary alcohols to aldehyde and ketones. The reaction involves reduction with NADH+

phosphoenopyruvate carboxykinase

functions in the gluconeogensis pathways  for conversion of oxaloacatate to phosphoenopyruvate and CO2.

Phosphofructokinase-1

function as regulatory enzyme of glycolysis to convert  fructose-6-phosphate  and ATP hydrolysis to glucose 1, 6, bisphosphate and ADP respectively.

Phosphoglycerate mutase.

An enzyme involved in glycolytic pathway, it catalysed the 8th step of glycolysis.

Hexokinase- an enzyme of glycolytic pathway invloved in phosphorylation of glucose, to intiate the process of glycolysis.

Pyruvate dehydrogenase

This is an enzyme that converts pyruvate to acetyl Co-A.

therefore it plays no role in the two pathways, because glycolytic pathway ends with pyruvate production.

Explanation: