Regulation
Step-by-step explanation:
a) Glycolysis: Glycolysis is an oxidative pathway to fulfill the energy demand of cell
- Includes 10 sequential steps which can be divided into two separate phase:
- Preparatory phase: Glucose is phosphorylated in 6th and 1st carbon and then cleaved in 3-C sugar, 2 ATP consumed in this phase
- Pay off phase: is the one in which 3C sugar is sequentially oxidized to yield ATP, NADH and pyruvate
- All irreversible steps of glycolysis are regulatory steps and catalysed by hexokinase, phosphofructokinase-1(PFK-1) and pyruvate kinase
- Hexokinase catalyses conversion of glucose to glucose 6 phosphate, ATP act as an activator
- PFK-1 catalyses conversion of Fructose 6 phosphate to fructose 1,6 bisphosphate
- Pyruvate kinase catalyses conversion of phosphoenol pyruvate to pyruvate, here ATP is generated
Gluconeogenesis: It is the process which synthesizes glucose from non carbohydrate material, fulfills the glucose requirement of cell
- At cellular level gluconeogenesis starts from matrix of mitochondria and completed in cytoplasm
- Regulatory enzymes of gluconeogenesis include pyruvate carboxylase and Fructose 1,6 bis-phosphatase
- Pyruvate carboxylase catalyses conversion of pyruvate to oxaloacetate
- Fructose 1,6 bis-phosphatase catalyses conversion of fructose 1,6 bisphosphate to fructose 6 phosphate
b) When cellular concentration of ATP increases then it means energy level is high in cell so glycolysis is suppressed and gluconeogensis is favored
c) When cellular concentration of ATP decreases then it means energy level is low in cell which favors glycolysis and suppress gluconeogenesis
d) High blood sugar releases insulin which favors glycolysis by increasing fructose 2,6 bisphosphate level and inhibits gluconeogenesis
e) Low blood sugar releases glucagon which inhibits glycolysis and stimulate breakdown of glycogen in liver cells and favors gluconeogenesis