1. How might a-carnitine deficiency account for triacylglycerol accumulation in
ID: 928481 • Letter: 1
Question
1. How might a-carnitine deficiency account for triacylglycerol accumulation in the muscles? Would the lipid accumulate in the cytosol or mitochondria of the cells? Why?
2. Replacement of normal dietary fat by triacylglycerols containing medium-chain (8 or 10 carbon) fatty acids has proved effective in some cases. What would this therapy be expected to work? Provide documentation.
3. In what ways are the fuel supply and hormonal signals similar in untreated diabetes mellitus and starvation? In what ways are they dissimilar?
4. Protein-Energy Malnutrition (PEM) is a common manifestation in cirrhotic patients with a reported incidence of 65-90%. One treatment technique is to add branched chain amino acids and/or their keto-analogs to the diet. Why do you think clinicians use this as a potential treatment?
5. Indicate whether you would expect the following enzymes or processes to be most active in the Fed or Starved state:
a. acetyl CoA carboxylase
b. synthesis of triacylglycerol in adipocytes
c. oxidation of acetoacetate and beta-hydroxybutyrate
d. chylomicron synthesis in the small intestine and metabolism in plasma
e. beta-oxidation in the liver
6. Discuss the net ATP generation/loss for the following situation. Starting with a-linolenic acid (18:3), elongate and desaturate to form docosahexaenoic acid (22:6). Take docosahexaenoic acid through the beta-oxidation cycle to generate energy. Look at double bonds and show how you came up with the number of ATP molecules.
Explanation / Answer
1)
Normally our body needs to transport acyl-CoA into the mitochondria to metabolize it for energy. However, acyl-CoA cannot simply diffuse through the mitochondrial membrane. Therefore, we need carnitine to bind to it as a transport mechanism. Without it, all the acyl-CoA (which originally came from triacylglycerols from your diet) will be stuck outside in the cytosol. It then accumulates since there's no place for it to go to become degraded for energy.
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