Problem 1
What are the two primary molecules that link anabolic and catabolic reactions?
Problem 2
Name some of the key metabolic intermediates that are seen in more than one pathway.
Problem 3
Many components of the glycolytic pathway and the citric acid cycle are direct exit or entry points to metabolic pathways of other substances. Indicate another pathway available to the following compounds: (a) Fructose- 6 -phosphate (b) Oxaloacetate (c) Glucose- 6 -phosphate (d) Acetyl-CoA (e) Glyceraldehyde-3-phosphate (f) \(\alpha\) -Ketoglutarate (g) Dihydroxyacetone phosphate (h) Succinyl-CoA (i) 3 -Phosphoglycerate (j) Fumarate (k) Phosphoenolpyruvate (l) Citrate {m} Pyruvate
Problem 4
People who begin to lose weight often have a rapid weight loss in the first few days. Common knowledge says that this is "just" because of a loss of water from the body. Why might this be true?
Problem 5
The functioning of a particular pathway often depends not only on control enzymes in that pathway but also on control enzymes of other pathways. What happens in the following pathways under the indicated conditions? Suggest what other pathway or pathways might be influenced. (a) High ATP or NADH concentration and the citric acid cycle. (b) High ATP concentration and glycolysis. (c) High NADPH concentration and the pentose phosphate pathway. (d) High fructose- \(2,6-\) bisphosphate concentration and gluconeogenesis.
Problem 10
If you had your choice of doing research on any topic in this book, which would you choose? Why do you consider that topic to be interesting and important?
Problem 12
What do we mean when we say that there is no storage form for protein? How is this different from fats and carbohydrates?
Problem 13
What is the relationship between saturated fatty acids and LDL?
Problem 14
What is leptin, and how does it work?
Problem 20
A cat named Lucullus is so spoiled that he will eat nothing but freshly opened canned tuna. Another cat, Griselda, is given only dry cat food by her far less indulgent owner. Canned tuna is essentially all protein, whereas dry cat food can be considered \(70 \%\) carbohydrate and \(30 \%\) protein. Assuming that these animals have no other sources of food, what can you say about the differences and similarities in their catabolic activities? (The pun is intended.)
