1. A.) When consuming a carbohydrate-rich, mixed meal, explain why/how hepatic glycogen synthesis increases and glycogenolysis decreases in response to the meal. In your response, you should discuss substrate availability, hormones involved, and activation/inactivation of key enzymes by allosteric and co-valent modification, depending on the pathway. B.) High fructose corn syrup, which is composed of 55% fructose and 45% glucose, was consumed in the meal. Explain whether the glucose and fructose found in HFCS would occupy the same or different spots on the auto-oxidation hierarchy within the hepatocytes (liver cells) and provide justification for your reasoning. A. B.

2.) The liver pyruvate dehydrogenase (PDH) complex activity is low in response to a 12-h fast while the person is still sleeping in the morning, a phenomenon that severely affects hepatic carbohydrate use as a fuel. In no more than 100 words, thoroughly explain why/how the characteristics of the post- absorptive, sedentary state affect hepatic PDH complex activity and hepatic use of carbohydrate as a fuel. 3.) Muscle contraction requires ATP and Ca++. In no more than 75 words, explain how neural stimulation of muscle contraction and the increased energy demand during intense exercise ensure that adequate ATP is synthesized via glycogen and glycolytic metabolism within the first minute of muscle contraction, prior to the increase in cAMP via epinephrine stimulation of the muscle. Note: Your answer should not include any discussion of epinephrine and its role in stimulating cAMP formation but should include key enzymes involved as well as how their activity is modified.