QUESTION 1 For each characteristic of fatty acid metabolism listed below, fill i

Question

QUESTION 1

For each characteristic of fatty acid metabolism listed below, fill in the blank with whether it best describes:   

A= Fatty acid degradation

B= Fatty acid synthesis

C= Neither process

Occurs mostly in the cytoplasm _______

A methylene group is converted to a keto group _______

4-step reaction cycle is condensation, reduction, dehydration, reduction ______

Generates FADH2 ______

QUESTION 2

You are studying fatty acid metabolism in a strain of mice that is being fed a diet with very low amounts of carnitine. What impact would you expect this diet to have on fatty acid metabolism (either on FA synthesis or degradation) in the mice? Why?

QUESTION 3

You are studying fatty acid metabolism in a strain of mice that is transgenic for a mutation that disrupts the citrate binding site on acetyl CoA carboxylase I. What impact would you expect this mutation to have on fatty acid metabolism (either on FA synthesis or degradation) in the mice? Why

QUESTION 4

Now you are examining the adaptive control of fatty acid metabolism in mice. For each situation below fill in the blank with what effect you would expect to see on fatty acid metabolism where:

A= increase FA synthesis

B= decrease FA synthesis

C= increase FA degradation

D= decrease FA degradation

Transgenic mice overexpress SREBP1c ________

Transgenic mice overexpress PPAR _______

Transgenic mice have mutation to prevent ligand binding to PPAR ________

QUESTION 5

For each of the situations listed below determine the effect on cholesterol synthesis and fill in the blank where: A= increase cholesterol synthesis

B= decrease cholesterol synthesis

SREBP2 is highly resistant to proteolytic cleavage _______

HMG-CoA reductase is resistant to phosphorylation _______

Patient is taking a statin ________

Explanation / Answer

Fatty acid synthesis mostly occurs in the cytoplasm of the cells. Fatty acids are formed from acetyl-CoA and NADPH by fattyacid synthases.

In fatty acid synthesis, the methyl group from acetyl co A is converted to a keto group

Fatty acid degradation that is called Beta oxidation generates FADH2

2) The fatty acids are impermeable to the inner mitochondrial membrane and requires a a specialized carnitine carrier system for its transport from from cytosol to mitochondria. The acetyl Co A is conjugated to carnitine carnitine acyltransferase and the acetyl carnitine is translocated inside. The carnitine is recylced back for binding to other acetyl CoA. Diet less in carnitine will impair this pathway and hence the fatty acids cannot be oxidised in the mitochondria due to lack of carnitine. The mice might exhibit a fatty acid accumulation.

3) The  cytosolic acetyl-CoA is carboxylated into malonyl CoA by the enzyme acetyl CoA carboxylase. This is the the first committed step in the fatty acids synthesis. If mutation disrupts the acetyl CoA binding site there will be effect in the synthesis of fattyacid.

Acetyl Co A carboxylase does not bind to citrate so no effect will be oberved unless this site is not involved in any other activity like acetyl coA binding. Citrate is metabolised by the  ATP citrate lyase into acetyl-CoA and oxaloacetate.

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