What is False regarding HMP shunt and explain in detail?
Ans. is 'c' i.e., ATP is produced HMP shunt does not produce ATP. HMP shunt HMP shunt is a multicyclic process in which 3 molecules of glucose-6-phosphate give rise to 3 molecules of CO2 and 3 molecules of 5-carbon sugars (ribulose-5-phosphate). The latter are rearranged to generate 2 molecules of glucose-6-phosphate (through fructose-6-phosphate) and l molecule glyceraldehyde-3-phosphate. HMP shunt does not generate ATP. 3 Glucose-6-phosphate + 6 NADP - 2 glucose-6-phosphate + 1 glyceraldehyde-3-phosphate + 6 NADPH 3CO2 The reaction of HMP shunt are divided into two phases : - i) Phase I (Oxidative irreversible phase) : - During this phase, 3 molecules of glucose-6-phosphate are oxidized with generation of 6 molecules of NADPH, and three molecules of pentose phosphate (ribulose?5-phosphate), with liberation of three molecules of CO2. Metabolites produced during this phase are 6- phosphoglucanolactone, 6-phosphogluconate and ribulose-5-phosphate. ii) Phase II (Non-oxidative reversible phase) : - During this phase, pentose phosphate is conveed to intermediates of glycolysis, i.e., glucose-6-phosphate and glyceraldehyde-3-phosphate. Intermediary metabolites of this phase are xylulose-5-phosphate, ribose-5-phosphate, sedoheptulose-7-phosphate, erythrose-4- phosphate and fructose-6-phosphate. HMP shunt occurs in the cytosol. It is highly active in liver, adipose tissue, adrenal coex, lens, cornea, lactating (but not the nonlactating) mammary gland, Gonads (testis, ovary) and erythrocytes. Activity of this pathway is minimal in muscle and brain, where almost all of the glucose is degraded by glycolysis.