Question

Why Krebs cycle is also known as citric acid cycle.
A. Due to first stable product as citric acid
B. First stable product citric acid contain two carboxyl group
C. First stable product citric acid contain three carboxyl group
D. Citric acid is devoid of any -COOH group

Answer 1

Hint: Krebs cycle is a cycle of chemical reactions which are the major source of energy in the living organisms. The citric acid cycle or the Krebs cycle is a part of cellular respiration, which is the process where our body harvests energy from the food we eat.

Complete answer:
In biochemistry, Kreb’s cycle which is also known as the tricarboxylic acid cycle or the citric acid cycle, is one of the most important reaction sequences. Krebs cycle is a series of chemical reactions carried out in the living cell. In higher animals it is essential for oxidative metabolism of the glucose and other simple sugars including humans. The breakdown of glucose to water and carbon dioxide is a complex set of chemical interconversions referred to as carbohydrate catabolism, and of three major stages in the process, occurring between oxidative phosphorylation and glycolysis the Krebs cycle is the second.
Kreb’s cycle was named in recognition of the German chemist Hans Krebs. His research into cellular utilization of the glucose contributed to the modern understanding of this aspect of metabolism. Citric acid with three carboxyl groups is the first product generated by the sequence of conversions; hence it is named as citric acid cycle. The reactions are seen to comprise a cycle in as much as citric acid is both the final reactant and the first product, being regenerated at the conclusion of one complete set of the chemical rearrangements. Since citric acid contains three carboxyl groups (COOH), Citric acid is also called tricarboxylic acid. Therefore, the Krebs cycle is sometimes called the tricarboxylic acid cycle or TCA cycle.

Hence, the correct answer is option (C).

Note: In certain microorganisms, like bacterium Escherichia coli, in higher plants, and in the algae, the citric acid cycle is modified to a form called as the glyoxylate cycle, so named because of the prominent intermediate, glyoxylic acid.