Question

QUESTION 42 If citric acid builds up in a respiring cell, what effect does this have on respiration? Is this a positive or negative form of feedback regulation? Explain specifically how citric acid regulates the pathways (think about the enzymes involved). Why is this regulation of respiration advantageous for the cell? TTTT Paragraph v Arial 3 (120) %DOQ Τ'T,

Answer 1

Citric acid or citrate is the first product of Krebs cycle also regulates the glycolysis process and hence affects the cellular respiration which involves glycolysis ----> Krebs cycle ----> electron transport chain. The production of citrate leads to it build up and results in the slow down of glycolysis process.

It is a type of feedback inhibited or negative regulation as it inhibits the enzyme phosphofructo kinase (PFK) which is required for the phosphorylation of fructose-6- phosphate to fructose biphosphate.

Glucose AMP ATP, Citrate ✓ Fructose-6. phosphate PHOSPHOFRUCTO- KINASE (PFK) Fructose-1,6 bisphosphate Pyruvate >= regulator activates enzyme Horegulator in hibits enzyme

Negative feedback or feedback inhibition actually controls the biochemical process and stops the process when the product (citric acid) is enough and hence maintains a homeostasis in the cell.