Question

Glycogen and Fatty Acids are used to store energy. Describe and contrast the physiological states that would result in breakdown vs. those that would favor synthesis of these energy stores (include what is going on in different organs). Glycogen can be synthesized from, or broken down to Glucose 1P. Similarly, Fatty acids can be synthesized from, or broken down to Acetyl CoA. Explain why, in each case, both the breakdown and synthesis pathways are energetically favorable. You do not need to write the whole pathway, just succinctly summarize key features that change the overall energetics of biosynthetic vs. the breakdown pathways to make both directions favorable.

Answer 1

Glycogen synthase (UDP-glucose-glycogen glucosyltransferase') is an enzyme involved in converting glucose to glycogen. It takes short polymers of glucose and converts them into long polymers. It is a glycosyltransferase enzyme that catalyses the reaction of UDP-glucose and (1,4-αD-glucosyl)n to yield UDP and (1,4-α-D-glucosyl)n+1. In other words, this enzyme converts excess glucose residues one by one into a polymeric chain for storage as glycogen. Its presence in the bloodstream is highest in the 30 to 60 minutes following intense exercise. It is a key enzyme in glycogenesis.

Fatty acids, stored as triglycerides in an organism, are an important source of energy because they are both reduced and anhydrous. The energy yield from a gram of fatty acids is approximately 9 kcal (37 kJ), compared to 4 kcal (17 kJ) for carbohydrates. ... Carbohydrates, on the other hand, are more highly hydrated