Module 1: Carbohydrates II

Question 1

Where is glycogen primarily stored? How much is stored?

Answer 1

• Liver and muscle
• Due to more muscle mass, the quantity of glycogen in muscle (250gm) is about 3 times higher than that in the liver (75gm)

Question 2

Functions of liver glycogen

Answer 2

• Liver glycogen functions to store and export glucose to maintain blood glucose level between meals
• After 12-18 hrs of fasting, liver glycogen is almost totally depleted

Question 3

Functions of muscle glycogen

Answer 3

Serves as a fuel reserve for the supply of ATP during muscle contraction

Question 4

Although muscle glycogen doesn’t yield ____ _______ (as muscle lacks ____-_-_____), _____ formed by glycolysis in muscle can undergo transamination to _____, which is exported from muscle and used for ____________ in liver

Answer 4

• Free glucose
• Glucose-6-phosphatase
• Pyruvate
• Alanine
• Gluconeogenesis

Question 5

What enzymes are involved in glycogenesis? Are they active/inactive, and what happens to glucose?

Answer 5

• Glycogen synthase b (inactive) -> Glucose is phosphorylated
• Glycogen synthase a (active) -> Glucose is De-phosphorylated

Question 6

Enzymes involved in glycogenolysis

Answer 6

• Phosphorylase a regulation -> ACTIVE Pi**, Ca2+*, Catecholamine
• Phosphorylase b regulation -> INACTIVE 5’-AMP

Question 7

What is Carbo-loading?

Answer 7

Increases muscle glycogen content more than mixed or protein + fats diets with the same amount of calories

Question 8

How they determine that Carbo-loading was an efficient way to increase glycogen stores?

Answer 8

Relationship between initial glycogen content in the quadriceps muscle in nine subjects who had been on different diets, and maximal work time when working at a given load demanding 75% maximal aerobic power

Question 9

Amphibolic Pathway

Answer 9

A metabolic pathway that functions in both

anabolism and catabolism

Question 10

Cost of gluconeogenesis from an energy input/output perspective

Answer 10

-2 moles of pyruvate to 2 moles of 1,3-bisphosphoglycerate consumes 6 moles of ATP

Question 11

Cost of glycolysis from an energy input/output perspective

Answer 11

• 2 moles of pyruvate only yields 2 moles of ATP
• This is why ketogenic diets work so well to lose weight
• The process of gluconeogenesis very costly from an energy standpoint

Question 12

What is an anaplerotic reaction?

Answer 12

Reactions that can replenish the intermediates lost during biosynthesis