Review Problems week 13 ( Lipid and sterol biosynthesis, nucleic acids)
1) Outline the pathways for the biosynthesis of diacyglycerol and phosphatidic acid.
2) How is phosphatidic acid activated for conversion in phosphatidyl inositol?
3) What is the role of phosphoinositol trisphosphate?
4) What is the most common phospholipid in biological membranes? Outline the
biosynthesis of this molecule from phosphatidic acid.
5) What is the process called by which phosphatidyl serine is synthesized?
6) What are the precursors for ketosphingosine? Draw the mechanism for this synthesis.
Make sure to show how the relevant cofactor works. Outline the subsequent steps in the
synthesis of ceramide.
7) What class of lipids provides additional diversity for membrane surfaces? What
acidic carbohydrates are found in these molecules?
8) What are the three stages of cholesterol synthesis?
9) Outline the synthesis of the first five carbon intermediate in cholesterol biosynthesis.
10) Reduction of serum cholesterol is achieved by what class of compounds? What
enzyme do these molecules inhibit? Show the transformation this enzyme catalyzes.
11) Show the steps involved in converting three five carbon units into a C-15 unit used
for steroid biosynthesis.
12) In your answer to 11, there should also be a 10 carbon intermediate. Other than
biosynthesis, what role do these 10 carbon and 15 carbon molecules play?
13) What is the name of the 30 carbon unit in steroid biosynthesis?
14) Show the reaction used to activated the 30 carbon unit for subsequent cyclization.
15) Draw the structure and name the product of cyclization of the 30 carbon unit.
16) What are the nucleoside precursors for the formation of uric acid? Show the
sequence involved. What is the consequence of uric acid buildup?
17) What is the consequence of a deficiency in adenosine deaminase?
18) Outline the regulation of nucleic acid biosynthesis. A) pyrimidine and purine
biosynthesis B) ribonucleotide reductase
19) What are the functions of the different phospholipases in the degradation of
phospholipids?
20) Mammals have two different methods for synthesizing phosphatidyl choline. What
are these? (You will have to look in your book for this one).