Question

discuss the function, location, components and energy changes of the Glycolytic pathway?

Answer 1

The glycolytic pathway is an important metabolic process which converts the 6-carbon glucose into 3-carbon pyruvate and H+ and along this it produces energy in form of ATP and NADH. The main function of the glycolytic pathway is it helps in starting the process of cellular metabolism and hence it converts glucose into pyruvate which further enters into Kreb cycle. This is an anaerobic process as it does not require oxygen. The first half of glycolysis is energy requiring process in which ATP is required and second half is energy producing process. The glycolytic cycle is the cycle or process which takes place within the cytosol of cells inside all living organisms.

Components and energy requirement of cycle:-

i) The first step is when the glucose is converted into glucose-6-phosphate in presence of hexokinase enzyme and this requires a molecule of ATP.

ii) The second step is conversion of glucose-6-phosphate into fructose- 6-phosphate in presence of phosphohexose isomerase.

iii) The third step is conversion of fructose- 6-phosphate into fructose 1,6-bisphosphate in presence of phosphofructokinase-1 and this requires one molecule of ATP.

iv) The fructose 1,6-bisphosphate is converted into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate in presence of the enzyme aldolase and during this process, 6 carbon sugar is cleaved, and it forms two 3-carbon molecules.

v) In the 5th step, the enzyme isomerase helps in transforming the dihydroxyacetone-phosphate into glyceraldehyde-3-phosphate which is its isomeric form. In this first 5 steps, there is net two ATP molecules used.

vi) In the 6th step, glyceraldehyde -3 – phosphate is oxidized, and it produces 1,3-biphosphoglycerate in presence of glyceraldehyde-3-phosphate dehydrogenase and two molecules of NADH is produced. The product is formed by phosphorylation where a second phosphate is added to it.

vii) The 1,3-biphosphoglycerate donates a phosphate group to ADP and forms a molecule of ATP in presence of phosphoglycerate kinase. In this as 1,3-biphosphoglycerate is oxidized to carbonyl group, it forms 3-phosphoglycerate.

viii) In the 8th step, the 3-phosphoglycerate forms 2-phosphoglycerate in presence of mutase.

ix) In the 9th step, the 2-phosphoglycerate is converted to phosphoenolpyruvate through dehydration reaction. This tends to increase the potential energy by forming double bond.

x) The last step of glycolysis is when pyruvate kinase and PEP is converted pyruvate and it produces 2 molecules of ATP.

At the end of glycolytic pathway, it tends to produce two molecule of pyruvate along with 2 ATP molecules.