Question

Pyruvic acid is formed at the end of
A. Calvin cycle
B. Glycolysis
C. Krebs cycle
D. Pentose phosphate pathway

Answer 1

The pyruvic acid is a 2-oxo monocarboxylic acid and is a propionic acid derivative of 2-ketoacid. It is a pyruvate-conjugate acid. It supplies energy to the cells through a process known as the citric acid cycle.

Complete answer: The metabolic pathway which converts glucose into pyruvate (pyruvic acid) and a hydrogen ion, is glycolysis. For the high-energy molecules ATP (adenosine triphosphate) and NADH, the free energy released in this process is used to form the (reduced nicotinamide adenine dinucleotide). Glycolysis is a series of ten reactions that are catalyzed by enzymes. Many monosaccharides, such as fructose and galactose, can be converted into one of these intermediates. The end product of glycolysis is pyruvic acid. The glycolysis process begins with one glucose molecule and ends with two pyruvate molecules (pyruvic acid). Glycolysis begins with one glucose molecule and ends with two molecules of pyruvate (pyruvic acid), a total of four molecules of ATP, and two NADH molecules. In the initial half of the pathway, two ATP molecules were used to prepare the six-carbon ring for cleavage, so the cell has a net advantage of using two ATP molecules and 2 NADH molecules. If the cell is unable to further catabolize the pyruvate molecules, only two ATP molecules from one glucose molecule will be harvested.
So, option B is the correct answer.

Note: If pyruvate kinase, the enzyme that catalyzes the formation of pyruvate, is not available in appropriate amounts, the last step in glycolysis does not occur. The entire glycolysis pathway will continue to proceed in this situation, but in the second half, only two ATP molecules will be formed. So, for glycolysis, pyruvate kinase is a rate-limiting enzyme.