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Lecture Schedule

Biochemistry of Phospholipids and Steroids
(Membrane Lipids)

Learning Objectives and Guiding Questions

Reading assignment: Meisenberg, pp 381-397 (see also pp 220-224).

1. List the major phosphoglycerides (aka glycerophospholipids) and describe their structural features.

A. What is the name and structure of the core phospholipid from which all the others are derived?

B. Which of the phospholipids is deficient in ARDS (acute respiratory distress syndrome)? What is its common name?

C. Why are phospholipids amphipathic?

D. What is cephalin?

E. Which phospholipid has a role in intracellular signaling? (pg 588)

F. What structural feature distinguishes plasmalogens from the other phospholipids?

G. What fundamental structure is joined in a dimer to form cardiolipins?

2. Explain how the two major pathways for the synthesis of phosphoglycerides differ and how they are alike.

3. Outline the steps in the formation of phosphatidylinositol from CTP and phosphatidic acid.

A. What is phosphatidic acid?

B. What is phosphatidylinositol?

4. Outline the steps in the formation of phosphatidylcholine both from free choline and CTP and from phosphatidylserine.

A. How is choline activated?

B. What type of linkage do CDP-diglyceride and CDP-choline share in common?

C. How is phosphatidylcholine different from phosphatidylinositol?

D. Where does phosphatidyl ethanolamine occur in the synthesis pathways for phosphatidylcholine and phosphatidylserine?

5. Describe the role of phospholipases in the process of remodeling of phospholipids.

A. What type of fatty acid usually winds up on position 1? On position 2?

B. What is attached to the carbon at position 3?

6. Describe the steps in the formation of phosphatidyl choline from phosphatidyl ethanolamine.

A. What do each of these steps have in common?

B. And, what would be the name of that methyl donor?

7. Compare and contrast the structures of platelet activating factor and ethanolamine plasmalogen.

A. What type of linkage joins the acyl group to position 1?

B. What is the main difference between the acyl groups attached to position 2?

C. How is the ethanolamine added to the plasmalogen?

D. Do both of these molecules have a structural function?

8. Describe the components of the structure of sphingophospholipids and compare them to phospholipids.

A. What are some of the structural features of sphingosine?

B. What substitutes for glycerol in sphingolipids?

C. What role does ceramide play and just what is it anyway?

D. What is sphingomyelin?

9. Outline the formation of phosphatidyl inositol and cardiolipin from CDP-diglyceride.

A. What does cardiolipin have in common with Siamese twins? (pg 221)

B. Do either phosphatidyl inositol or cardiolipin contain nitrogen?

10. Describe the synthesis of sphingomyelin and gangliosides from palmitoyl CoA and serine.

A. How is sphingosine similar to a monoglyceride?

B. What condenses with sphingosine to form a ceramide?

C. How is a ceramide similar to a diglyceride?

D. What activated form of glucose is needed to condense with a ceramide to form a cerebroside?

E. How are gangliosides built from cerebrosides? (pg 222)

F. What does ceramide condense with to form sphingomyelin?

11. Describe the synthesis of gangliosides from ceramides.

A. What is the nature of the precursors that are added to the ceramides? What is a glycosphingolipid?

B. Where are they added to the ceramide?

12. Describe the synthesis of the A and B substance that determine the ABO blood groups.

A. What is H substance? How are the A and B substance related to the H substance?

B. Are there different genes for the enzymes that produce the blood types, or are they just different alleles? So, what are alleles anyway?

C. How do you get an O type? Can you get it in the heterozygous state?

D. How do you get the type A or type B phenotype? Can you get them in the heterozygous state?

E. Is an AB type heterozygous? It's nice to have an easy one now and then isn't it.

F. What percent of Caucasians have either type A or type O?

13. List some of the major diseases caused by defects in lysosomal enzymes that degrade sphingolipids.

14. Draw a cyclopentanoperhydrophenanthrene (CPPP) structure.

15. List the major classes of steroids and give an example of each.

A. How long is the side chain on cholesterol? How many total carbons does it have?

B. What modifications are made to the CPPP ring in cholesterol structure.

C. How is the side chain on cholic acid different from that of cholesterol?

D. How is deoxycholic acid different from cholic acid?

E. What makes the bile acids amphipathic and how does this affect their biological function?

16. List the major stages in the synthesis of cholesterol.

A. What is HMG-CoA and how is it related to mevalonic acid? From what precursor is it derived?

B. What is the role of activated isoprenoid units in the synthesis of cholesterol?

C. How is squalene related to these activated isoprenoid units?

D. Does squalene have the intact CPPP (cyclopentanoperhydrophenanthrene) nucleus? How many carbons in squalene?

E. How does lanosterol fit in to the process?

17. Explain the significance of the HMG-CoA reductase reaction.

A. How is the activity of HMG-CoA reductase regulated?

B. Why is HMG-CoA reductase regulated?

C. Give the site of action of cholesterol lowering drugs (e.g. the statins: lovastatin, mevastatin).

18. List the various roles of isoprene units other other than cholesterol precursors.

19. Outline the conversion of cholesterol to bile acids.

A. What are bile acids needed for?

B. What are the two major bile acids produced from cholesterol?

C. How does the quantity of bile acid production compare to other uses of cholesterol?

D. What is the rate limiting step in the conversion of cholesterol into bile acids?

E. What is a conjugated bile acid?

(Additional objectives concerning enterohepatic circulation and bile acids will be covered in the liver biochemistry objectives.)

Last revised 10/05/99

MedBiochem Home

Lecture Schedule

Biochemistry of Phospholipids and Steroids (Membrane Lipids)

Learning Objectives and Guiding Questions

Reading assignment: Meisenberg, pp 381-397 (see also pp 220-224).

1. List the major phosphoglycerides (aka glycerophospholipids) and describe their structural features.

A. What is the name and structure of the core phospholipid from which all the others are derived?

B. Which of the phospholipids is deficient in ARDS (acute respiratory distress syndrome)? What is its common name?

C. Why are phospholipids amphipathic?

D. What is cephalin?

E. Which phospholipid has a role in intracellular signaling? (pg 588)

F. What structural feature distinguishes plasmalogens from the other phospholipids?

G. What fundamental structure is joined in a dimer to form cardiolipins?

2. Explain how the two major pathways for the synthesis of phosphoglycerides differ and how they are alike.

3. Outline the steps in the formation of phosphatidylinositol from CTP and phosphatidic acid.

A. What is phosphatidic acid?

B. What is phosphatidylinositol?

4. Outline the steps in the formation of phosphatidylcholine both from free choline and CTP and from phosphatidylserine.

A. How is choline activated?

B. What type of linkage do CDP-diglyceride and CDP-choline share in common?

C. How is phosphatidylcholine different from phosphatidylinositol?

D. Where does phosphatidyl ethanolamine occur in the synthesis pathways for phosphatidylcholine and phosphatidylserine?

5. Describe the role of phospholipases in the process of remodeling of phospholipids.

A. What type of fatty acid usually winds up on position 1? On position 2?

B. What is attached to the carbon at position 3?

6. Describe the steps in the formation of phosphatidyl choline from phosphatidyl ethanolamine.

A. What do each of these steps have in common?

B. And, what would be the name of that methyl donor?

7. Compare and contrast the structures of platelet activating factor and ethanolamine plasmalogen.

A. What type of linkage joins the acyl group to position 1?

B. What is the main difference between the acyl groups attached to position 2?

C. How is the ethanolamine added to the plasmalogen?

D. Do both of these molecules have a structural function?

8. Describe the components of the structure of sphingophospholipids and compare them to phospholipids.

A. What are some of the structural features of sphingosine?

B. What substitutes for glycerol in sphingolipids?

C. What role does ceramide play and just what is it anyway?

D. What is sphingomyelin?

9. Outline the formation of phosphatidyl inositol and cardiolipin from CDP-diglyceride.

A. What does cardiolipin have in common with Siamese twins? (pg 221)

B. Do either phosphatidyl inositol or cardiolipin contain nitrogen?

10. Describe the synthesis of sphingomyelin and gangliosides from palmitoyl CoA and serine.

A. How is sphingosine similar to a monoglyceride?

B. What condenses with sphingosine to form a ceramide?

C. How is a ceramide similar to a diglyceride?

D. What activated form of glucose is needed to condense with a ceramide to form a cerebroside?

E. How are gangliosides built from cerebrosides? (pg 222)

F. What does ceramide condense with to form sphingomyelin?

11. Describe the synthesis of gangliosides from ceramides.

A. What is the nature of the precursors that are added to the ceramides? What is a glycosphingolipid?

B. Where are they added to the ceramide?

12. Describe the synthesis of the A and B substance that determine the ABO blood groups.

A. What is H substance? How are the A and B substance related to the H substance?

B. Are there different genes for the enzymes that produce the blood types, or are they just different alleles? So, what are alleles anyway?

C. How do you get an O type? Can you get it in the heterozygous state?

D. How do you get the type A or type B phenotype? Can you get them in the heterozygous state?

E. Is an AB type heterozygous? It's nice to have an easy one now and then isn't it.

F. What percent of Caucasians have either type A or type O?

13. List some of the major diseases caused by defects in lysosomal enzymes that degrade sphingolipids.

14. Draw a cyclopentanoperhydrophenanthrene (CPPP) structure.

15. List the major classes of steroids and give an example of each.

A. How long is the side chain on cholesterol? How many total carbons does it have?

B. What modifications are made to the CPPP ring in cholesterol structure.

C. How is the side chain on cholic acid different from that of cholesterol?

D. How is deoxycholic acid different from cholic acid?

E. What makes the bile acids amphipathic and how does this affect their biological function?

16. List the major stages in the synthesis of cholesterol.

A. What is HMG-CoA and how is it related to mevalonic acid? From what precursor is it derived?

B. What is the role of activated isoprenoid units in the synthesis of cholesterol?

C. How is squalene related to these activated isoprenoid units?

D. Does squalene have the intact CPPP (cyclopentanoperhydrophenanthrene) nucleus? How many carbons in squalene?

E. How does lanosterol fit in to the process?

17. Explain the significance of the HMG-CoA reductase reaction.

A. How is the activity of HMG-CoA reductase regulated?

B. Why is HMG-CoA reductase regulated?

C. Give the site of action of cholesterol lowering drugs (e.g. the statins: lovastatin, mevastatin).

18. List the various roles of isoprene units other other than cholesterol precursors.

19. Outline the conversion of cholesterol to bile acids.

A. What are bile acids needed for?

B. What are the two major bile acids produced from cholesterol?

Biochemistry of Phospholipids and Steroids
(Membrane Lipids)