Question

Scientists can use mutants to study metabolic pathways. These organisms have a mutation in a gene encoding a metabolic pathway enzyme that results in the activation of that enzyme. Saccharomyces cerevisiae (a yeast species) mutants are available that grow on pyruvate or ethanol, but not sugars or glycerol. Which of the following glycolytic enzymes is most likely affected?

1. triose phosphate isomerase

2. aldolase -phophoglucose isomerase (phosphohexose isomerase or glucose-6-phosphate isomerase)

3. hexokinase

4. pyruvate kinase

PLEASE HELP! I NEED TO KNOW THE ANSWER AND WHY? THERE WILL BE MORE QUESTIONS WITH DIFFERENT MUTANTS TO SOLVE. THANK YOU!!!

Answer 1

The correct answer is option 2. "aldolase -phophoglucose isomerase (phosphohexose isomerase or glucose-6-phosphate isomerase)".

Step-by-step explanation:

Phophoglucose isomerase, also known as Glucose-6-phosphate isomerase (GPI), is an enzyme that catalyzes the reversible conversion of glucose 6-phosphate into fructose 6-phosphate (aldose to ketose). This enzyme is essential in the glycolysis, because this enzyme catalyzes the first step of the metabolism of glucose. If mutants of Saccharomyces cerevisiae can grow on pyruvate or ethanol, but not sugars or glycerol it is likely that this enzyme is affected. This is explained because GPI has a role on metabolism of sugars or glycerol but not on the metabolism of pyruvate or ethanol.