Question

A mutation in yeast makes it unable to do electron transport. How will this mutation affect these yeast cells? Select all answer options below that are correct. Note--more than one answer option might be correct.

A. The mutant yeast cells will be unable to grow anaerobically.

B. The mutant yeast cells will be unable to grow with fatty acids as carbon source

C. The mutant yeast cells will not be able to survive in the presence of oxygen.

D. The mutant yeast cells will be able to grow with glucose as carbon source.

E. The mutant yeast cells will not be able to regenerate NAD+ so will die.

Answer 1

fatty acids are oxidized via beta-oxidation and acetyl CoA, NADH, FADH2 are produced, acetyl CoA is oxidized via the TCA cycle, and one ATP, one FADH2, and three NADH are produced.

NADH and FADH2 are oxidized via electron transport chain and using the energy of electrons in these reduced coenzymes, H+ from the matrix is pumped to the intermembrane space and an H+ gradient is generated, ATP synthase in the mitochondrial inner membrane space uses the energy of H+ gradient to make ATP from ADP and Pi.

In these mutant cells electron transport chain cannot occur so not much ATP can be produced from the fatty acids, so these mutants cannot grow with fatty acids as the carbon source.

Glucose molecules are oxidized via glycolysis, pyruvate oxidation, and TCA cycle, if the electron transport chain cannot occur, pyruvate produced by glycolysis cannot be oxidized, so pyruvate is converted to ethanol and carbon dioxide via alcohol fermentation, during this process NADH oxidized to NAD+, so that glycolysis can proceed and produce ATP from glucose.

This mutant yeast carries ou fermentation in the presence and absence of oxygen.

B. The mutant yeast cells will be unable to grow with fatty acids as a carbon source

D. The mutant yeast cells will be able to grow with glucose as carbon source.