Cellular Respiration and Enzymes

Glycolysis starts with the phosphorylation of glucose in G-6-P by using two ATP molecules in the presence of hexokinase enzyme.

Acetyl CoA acts as a connecting link between glycolysis and Kreb's cycle. In mitochondrial matrix, pyruvate combines with CoA to form acetyl CoA.

Lactic acid, which is produced due to anerobic respiration, accumulates in the muscles after vigorous exercise and leads to muscular fatigue. Hence, it is the correct option.

On complete oxidation, one molecule of acetyl coenzyme A produces 15 molecules of ATP in Kreb's cycle. Hence, this is correct.

Alpha-lipoic acid is a cofactor of pyruvate dehydrogenase complex and several other enzyme complexes.

Glycogenesis, glycogenolysis and gluconeogenesis. All three metabolic functions are carried out by liver to maintain sugar level of the body.

Both Assertion (A) and Reason (R) are correct and R is the correct explanation of A. The inhibition of glycolysis by oxygen is referred to as Pasteur effect.  This is due to inhibition of the enzyme phosphofructokinase by ATP and citrate (formed in the presence of O₂).

The enzymes for the TCA (Krebs) cycle are located in the mitochondrial MATRIX, not the inner membrane. The inner membrane contains the electron transport chain complexes. However, among the given options, the inner mitochondrial membrane is the closest and most relevant location for mitochondrial processes. The outer membrane, endoplasmic reticulum, and lysosomes have no role in the TCA cycle.

Enzymes have a particular optimum range of working temperature, below which their activity decreases.

temperature coefficient

Oxyrase is a bacterial respiratory enzyme that can be put in media; it combines O₂ with H⁺ to remove O₂ by forming H₂O and turns the petri dish into a mini-anaerobic chamber. Anaerobic chambers with air locks are filled with inert gas.

The respiratory quotient (RQ or respiratory coefficient) is a dimensionless number used in calculations of basal metabolic rate (BMR), when estimated from carbon dioxide production. It is 1 for carbohydrates as numbers of oxygen and carbon dioxide molecules are equal.

Oxidative phosphorylation (OXPHOS) is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy, which is used to reform ATP. In most eukaryotes, this takes place inside mitochondria.

Warburg effect refers to the biochemical phenomenon of aerobic glycolysis that contributes to cancer cell proliferation.

Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes, typically occurring in anaerobic conditions. It is a form of incomplete oxidation of glucose used by organisms like yeast and bacteria to generate energy without oxygen.