Cholesterol Metabolism

Question 1

1. The liver accounts for at least _____ % of synthesized cholesterol.
2. _______ ________-________ organs are also very active.
3. Where is the subcellular location?
4. Where do all the C atoms in cholesterol come from?

Question 2

1. Put the following reactants and products in the correct order:
   HMGCoA reductase, Mevalonate, HMGCoA synthase, 2 acetylCoA, HMGCoA, Thiolase, Acetoacetate
2. Which enzyme is the major control point for choleseterol synthesis?
3. What group of drugs inhibits this enzyme?
4. Where does the enzyme reside in the cell?

Question 3

1. How many steps are involved in the formation of ispopentenyl diphosphate?
2. What is the reactant for this reaction?
3. What is going on during these 4 steps?

Question 4

1. For the formation of squalene, put the following in the correct order:
   Squalene, isoprenoid, geranyl diphosphate, isoprenoid, farnesyl diphosphate, isoprenoid, farnesyl diphosphate, squalene synthase

Question 5

1. For the squalene -> lanosterol reaction, put the following in the correct order
   oxidosqualene lanosterol cyclase, squalene, lanosterol, squalene epoxidase
2. what additional reagents are required for squalene epoxidase function?
3. Lanosterol is the _______ sterol produced in the pathway to cholesterol

Question 6

1. For lanosterol -> cholesterol, describe the _____ steps that take place (C location and what is happening at each C)
2. Where does this reaction take place?

Question 7

1. What are prenylated proteins?
2. Where does this protein reside?

Answer 7

1. Membrane-associated proteins (GTP-binding) prenylated with farnesyl or gernylgeranyl residues
2. Prenylated proteins are anchored to the membrane

Question 8

1. What is dolichol formed from?
2. dolichol is required for which synthesis process?

Answer 8

1. dolichol is formed from farnesyl diphosphate plus up to 16 more isopentenyl residues
2. dolichol is required for synthesis of N-linked glycoproteins

Question 9

1. What is ubiquinone formed from?
2. What ubiquinone required for?

Answer 9

1. upiquinone is formed from farnesyl diphosphate and 3-7 isopentenyl residues
2. ubiquinone is required for the electron transport chain