Test: Glycolysis - UPSC MCQ

The main role of carbohydrates in metabolism is to serve as a major source of energy for living cells. They are broken down to release energy, which is essential for various metabolic processes.

The three principal monosaccharides resulting from digestion are glucose, fructose, and galactose, which are crucial for energy production.

Glycolysis is a sequence of 10 enzyme-catalyzed reactions that convert glucose into pyruvate while producing ATP, making it a fundamental metabolic pathway.

Glycolysis occurs in the cytosol, where the enzymes necessary for the pathway are located, facilitating the breakdown of glucose.

Under anaerobic conditions, the end product of glycolysis is lactate, formed when pyruvate is reduced to regenerate NAD⁺.

Hexokinase catalyzes the phosphorylation of glucose to form glucose 6-phosphate, a key regulatory step in glycolysis.

Phosphofructokinase catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, and this step is crucial as it is a major regulatory point in glycolysis.

NAD⁺ acts as an electron acceptor in glycolysis, getting reduced to NADH during the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.

Substrate-level phosphorylation in glycolysis allows for the direct generation of ATP from ADP using high-energy intermediates, independent of oxygen.

Pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate, generating ATP in the process, making it a key step in glycolysis.

Under aerobic conditions, a total of 8 ATP can be generated from one molecule of glucose during glycolysis, including those produced from NADH that enters the electron transport chain.

In anaerobic glycolysis, pyruvate is converted into lactate to regenerate NAD⁺, allowing glycolysis to continue in the absence of oxygen.

ATP acts as an allosteric inhibitor of phosphofructokinase, signaling that the cell has sufficient energy and reducing the enzyme's activity.

Aerobic glycolysis yields more ATP compared to anaerobic glycolysis because it allows for the complete oxidation of glucose through the Krebs cycle and oxidative phosphorylation.

The committed step in glycolysis refers to the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate, which commits the substrate to continue through the glycolytic pathway.