Question

In glycolysis, the end product is
a. Protein is converted into glucose
b. Glucose is converted into glycogen
c. Starch is converted into glucose
d. Glucose is converted into pyruvic acid

Answer 1

Hint: All organisms have a mechanism involving enzymes that helps in glucose oxidation without using oxygen. This process of breakdown of glucose is known as glycolysis. In plants, the glucose which is used is either from the sucrose produced during photosynthesis, or from the stored carbohydrate. For anaerobic organisms, glycolysis is the only process used as respiration. Glycolysis occurs in the cytoplasm of the cell.

Complete answer:
Glycolysis is composed of two words, ‘Glycos’ means glucose and ‘Lysis’ means breakdown. So, glycolysis means breakdown of glucose. The process of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, hence it is also known as the EMP pathway.
In the process of glycolysis, one molecule of glucose undergoes oxidation (partial) and produces two molecules of pyruvic acid.

The starch converts into glucose and fructose by the enzyme invertase, before entering in the cycle. The first step is phosphorylation of glucose/fructose to form glucose-6-phosphate with the help of enzyme hexokinase. Then isomers of glucose-6-phosphate, which is fructose-6-phosphate, is formed by the enzyme isomerase. Fructose-6-phosphate is then converted into fructose 1, 6-bisphosphate, and the enzyme phosphofructokinase is used in this step.

Fructose1, 6-bisphosphate then splits into two molecules, dihydroxyacetone phosphate and 3-phosphoglyceraldehyde (PGAL). This PGAL is then converted into 1, 3-diphosphoglycerate (BPGA), and then BPGA is converted into 3-phosphoglyceric acid (PGA). PGA is converted into phosphoenolpyruvate (PEP). In the last step, PEP is converted into pyruvic acid.

Hence, the correct answer is option (D).

Note: The end product of glycolysis is pyruvic acid, along with synthesis of high energy molecules of ATP and NADH. The pyruvic acid synthesised in the glycolysis cycle is then utilised in the citric acid cycle, where it combines with Acetyl Co-A to produce energy.