Reading Guide, Pratt and Cornely Chapter 17
1. What are the structural and functional differences between chylomicrons, LDLs, and HDLs?
2. Fatty acids are the main metabolic fuel in __________ tissue in humans.
3. Fatty acids are activated in the cytosol by formation of the ______________ high energy bond
at the expense of two _____________ high energy bonds.
4. What is the role of the carnitine transporter?
5. Draw the four steps of degradation of this four carbon fatty acid to two acetylCoA.
6. Your book says that 14 ATP can be produced from each round of b-oxidation. That is true
except for the last step. How many ATP can be produced by full oxidative phosphorylation of
the four carbon fatty acid in problem 5.
7. How many net ATP could be produced from an 18 carbon fatty acid? (Remember activation.)
8. Why are additional enzymes needed for the b-oxidation of unsaturated fatty acids?
9. Odd-carbon fatty acids produce _____________ as their final product. This compound must
be converted to ____________ and then to Acetyl CoA for full oxidation.
10. Processing of odd-carbon fatty acids requires the rare vitamin ________________.
11. What is the function of the peroxisome? Why are peroxisomal defects fatal?
12. Fill in the table to contrast fatty adic degradation and synthesis:
Degradation
Synthesis
location
Attachment cofactors
Redox cofactors
energetics
13. Refer to Figure 17.11 and Figure 14.17. What is the role of the citrate transport system?
14. What is the rate-controlling step of fatty acid biosynthesis? Why does it make sense that
biotin is the cofactor involved?
15. ________________ is the donor of the 2 carbon acetyl units that are used to build fatty acids.
16. What is the thermodynamic purpose of putting a carboxylate on acetyl CoA prior to
incorporation into fatty acid?
17. Show the steps involved in reduction of the ketone in fatty acid synthesis. Which cofactor is
used? In which step(s)? Where does this cofactor come from?
18. Account for the amount of ATP equivalents required to synthesize palmitate (16 carbons.)
19.Packaging several enzyme activities into one ______________ protein like mammalian fatty
acid synthase allows the enzymes to work and be controlled in a coordinated fashion.
20. In addition to fatty acid synthase, other enzymes are necessary to _______________ and
_______________ fatty acids. We do not have enzymes to make w-3 or w-6 fatty acids—they
are termed _______________fatty acids because we must obtain them through diet.
21. Although saturated fats and trans fats are correlated to health risks, scientists do not know
__________________. Why is it difficult to know if it is better to eat butter or margarine?
22. Why does it make sense that malonyl-CoA inhibits-oxidation? Where is that process
inhibited? Why does it make sense that citrate activates ? Where is that process activated?
23. What are the structures of two metabolically important ketone bodies? Under what conditions
are ketone bodies formed? Why are they metabolically important?
24. What metabolic components are triacylglycerides made from?
25. Which nucleotide is necessary to activate diacylglycerides to form membrane components?
How are new membranes formed?
26 Cholesterol synthesis and ketogenesis start the same way chemically. How are they
distinguished?
27. Isoprenoids are made out of ___ carbon units. Cholesterol is made by linking 6 isoprene units
into a compound called _______________, which is then processed to make cholesterol.
28. Cholesterol synthesis is regulated at the enzyme _________________________, which
catalyzes the formation of ___________________. The drug class referred to as
_________________ inhibits this enzyme, lowering serum cholesterol levels.
29. What are four fates of newly synthesized cholesterol?
30. What are the roles of HDL and LDL in cholesterol transport? What is the only way to
dispose of excess cholesterol from the body? What medical problems are caused by defects in
LDL receptors?