Lipid metabolism

Question 1

What happens with the OH groups on glycerol?

Answer 1

They’re all esterified to (usually) all different fatty acids

Question 2

Fatty acids account for how much of biological energy?

Answer 2

95%

Question 3

What percent of fatty acids are unsaturated?

Answer 3

50%.

Question 4

What percent of TAG-FA is oleic acid?

Answer 4

46% (18:1)

Question 5

Two activators of HSTL

Answer 5

Epinephrine and ACTH.

Question 6

How is HSTL activated through epinephrine?

Answer 6

Upregulation of cAMP and PKA

Question 7

What other factors are needed for lipolysis to be active?

Answer 7

Adrenal cortical hormones and thyroid hormones

Question 8

Perilipin

Answer 8

Coats the surface of fat droplets and must be phosphorylated in order for HSTL to be translocated to the surface of the fat droplet

Question 9

Fate of released fatty acid

Answer 9

Binds to albumin and is transported to the liver for beta-oxidation

Question 10

Fate of released glycerol

Answer 10

Transported to the liver/kidney, phosphorylation by glycerol kinase, and takes part in gluconeogenesis

Question 11

Allosteric inhibitor of acetyl coA carboxylase

Answer 11

Fatty acyl CoA

Question 12

Describe the process of overcoming the rate-limiting step in beta-oxidation

Answer 12

Increased fatty acid concentration increases the overall amount of substrates for beta-ox, which helps drive that. It also decreases the amount of malonyl CoA, the only physiological inhibitor of carnitine palmitoyl transferase-1, which is the rate-limiting step in beta-oxidation.

Question 13

Increased beta-oxidation increases the concentration of what type of molecule?

Answer 13

Ketone bodies

Question 14

What happens with glycolysis in cells that are undergoing beta-oxidation?

Answer 14

Glycolysis will decrease because of ATP’s allosteric inhibition on PFK-1

Question 15

During beta-oxidation, for what can the ATP be used in part?

Answer 15

Gluconeogenesis

Question 16

Good users of fatty acids

Answer 16

Liver
Skeletal muscle
Heart
Kidney cortex

Question 17

Tissues that do not or cannot use fatty acids as a fuel source

Answer 17

Brain
Red blood cells
Adrenal medulla
Nervous system
Lens

Question 18

Stoichiometry of beta-oxidation

Answer 18

1 Palmitoyl-CoA + 7 FAD + 7 NAD+ + 7CoA + 7H2O ->

8 Acetyl CoA + 7 FADH2 + 7 NADH + 7H+

Question 19

Overall, how many ATP does beta-oxidation produce?

Answer 19

106 ATP

Question 20

Fatty acids are degraded by . . .

Answer 20

Sequential removal of 1 acetyl CoA at a time (produces one NADH + H and 1 FADH2 per round)

Question 21

Carnitine

Answer 21

Transports fatty acids into the mitochondria to be oxidized

Question 22

Primary carnitine disorder

Answer 22

Malformation/absence of the carnitine transporter

Question 23

Secondary carnitine disorder

Answer 23

Defect in CPT-1 or CPT-2

Question 24

LCAD, MCAD, and SCAD

Answer 24

Long, medium, and short-chain acylCoA dehydrogenases (there are separate enzymes for different length acyl CoAs)

Question 25

MCAD deficiency

Answer 25

May be linked to SIDS

Question 26

What are the ketone bodies found in humans?

Answer 26

Acetoacetate, beta-hydroxybutyrate, and acetone

Question 27

How is acetone formed?

Answer 27

Spontaneously in a decarboxylation reaction; no enzyme is involved

Question 28

Rate-limiting enzyme in ketone body formation

Answer 28

HMG-CoA synthase (found ONLY in the liver)

Question 29

What enzyme allows ketone bodies to be utilized?

Answer 29

Acetoacetate:succinyl CoA transferase (NOT found in the liver)

Question 30

How is ketone body formation regulated?

Answer 30

By the regulation of beta-oxidation