In a laboratory experiment, two groups of rats are fed two different fatty acids as their sole source of carbon for a month. The first group gets heptanoic acid (7:0), and the second gets octanoic acid (8:0). After the experiment, a striking difference is seen. The first group has gained weight, whereas the second group is weak and has lost weight as a result of losing muscle mass. Explain the biochemical basis for this difference by answering the following questions:
a) Describe the differences in the beta oxidation pathways between the two fatty acids. Draw out structures that would prove your point. You don't need to repeat the steps in beta oxidation, just state the number of rounds.
b) What are the major end products for the breakdown of 7:0 and 8:0? Explain how the end products can lead to different metabolic pathways that may result in the physical differences in the two rat groups.
c) How much net ATP can one get out of 1 molecule of 7:0 and 8:0? Please account for the fatty acid activation step. You don't need to show the beta oxidation pathways, but please show the math and provide a brief explanation of how you have derived your answer.