Glycogenesis And Gluconeogenesis

Glycogenesis And Gluconeogenesis

Glycogenesis.
Answer.

Glycogenesis/Glycogen Synthesis Definition

Glycogenesis is the formation of glycogen from glucose

Glycogenesis/Glycogen Sites

• Glycogenesis takes place in the liver and skeletal muscles
• Storage capacity of glycogen in a normal adult man (70 kg) is
  • Liver – 70 to 110 grams
  • Skeletal muscles- 240 to 250 grams

Reactions Of Glycogenesis

• Glucose is phosphorylated to glucose 6 phosphate by the enzyme glucokinase
• Glucose 6 phosphate is converted to glucose 1 phosphate by the enzyme phosphoglucomutase
• Glucose 1 phosphate then reacts with UTP (uridine triphosphate) to form UDP glucose (uridine diphosphate glucose) under the influence of the enzyme UDPG pyrophosphorylase
• C1 of the glucose of UDP glucose forms a glycosidic bond with the C4 of glucose of glycogen primer
• The enzyme required is glycogen synthase and UDP is liberated in the reaction
• A pre-existing glycogen primer must be present to initiate the reaction
• In this way an existing glycogen chain can be repeatedly extended by one glucose unit at a time.
• When the chain has lengthened to a minimum of 11 glucose units, branching enzyme transfers 6 glucose units, thus establishing a branch point in the molecule
• The branches grow by further additions and further branching
• 2 ATP’s are required for glycogenesis.