Fatty Acids, Ketones, Eicosanoids

Question 1

How do fatty acids enter mitochondria, and how are CoA-SH, carnitine, carnitine-palmitoyl transferases I & II, and carnitine carrier proteins involved?

Question 2

For saturated fatty acids with an even number of carbons, what are the four steps of beta-oxidation? Name the enzymes (and any cofactors) in this process; what products are made?

Question 3

What are the products of saturated fatty acids with an odd number of carbons?

Question 4

What are some important biological functions of lipids?

Question 5

Where in cells do the different processes of lipid synthesis occur?

Question 6

What is required for lipid synthesis—what are the sources of carbon, electrons & energy? Compare/contrast with the process of lipid catabolism.

Question 7

How is malonyl-CoA made, and what is the source of the three carbons of the malonyl moiety?

Question 8

Where does malonyl-CoA synthesis occur?

Question 9

Describe how malonyl-CoA is involved in regulation of fatty acid (FA) metabolism—why is it better for regulating FA synthesis than acetyl-CoA?

Question 10

What is the function of FAS?

Question 11

How is palmitate (16:0) synthesized in mammalian cells?

Question 12

Describe the roles of: acetyl-CoA carboxylase (ACC); fatty acid synthase (FAS); acyl carrier protein (ACP)

Question 13

Summarize the reactions involved in palmitate synthesis

Question 14

Palmitate contains 16 carbons; why are only seven malonyl-CoA required for its synthesis?

Question 15

Where do these reactions occur, and what are possible fates of the products of these reactions?

Question 16

Describe/diagram how acetyl-CoA from mitochondria is moved to the cytosol for FA synthesis (include intermediates, enzymes involved, and return of intermediates to the mitochondrial matrix)

Question 17

Relate the cellular location of FA synthesis with pathways that serve as sources of NADPH (e.g. in liver cells)

Question 18

Describe how FA oxidation in mitochondria and FA synthesis in cytosol can be reciprocally regulated by malonyl-CoA

Question 19

Describe how citrate and palmitoyl-CoA act as regulators; how is ACC activity affected by glucagon and epinephrine?

Question 20

What are two modifications to palmitate that can form additional kinds of FA?

Question 21

In what cellular compartment are fatty acids elongated?

Question 22

Describe the activity of fatty acid desaturases

Question 23

Briefly describe the overall pathway in the liver leading from acetyl-CoA to the ketone bodies acetone, acetoacetate, and D-beta-hydroxybutyrate.

Question 24

What is a beneficial fate of ketone bodies in metabolism?

Question 25

What is one serious physiological consequence of the overproduction of ketone bodies (e.g. in diabetes or starvation)?

Question 26

a.
How are steroids made from cholesterol—is it the same pathway as FA synthesis?

Answer 27

acetate → HMG-CoA → mevalonate → isoprenes → squalenes → sterols

Question 28

Why are HMG-CoA reductase (enzyme) and mevalonate (intermediate compound) important?

Question 29

Describe one example of how an eicosanoid signaling molecule can be synthesized from a membrane phospholipid

Question 30

What is the role of phospholipase A2 (PLA2)?

Question 31

Which class of enzyme converts arachidonic acid to prostaglandins (with cyclic structure)?

Answer 32

phospholipid → arachidonic acid (FA) → signal molecule (e.g. prostaglandins, leukotrienes)

Question 33

Which class of enzyme converts arachidonic acid to leukotrienes?

Question 34

cyclooxygenases (COX I and COX II)

Question 35

lipooxygenases