Deck 16: Lipid Metabolism

Question 1

Ketone bodies can be used as an alternative fuel source by the liver.

Answer 1

False

Question 2

Propionyl-CoA, the end product of β-oxidation of odd-chain fatty acids can enter the citric acid cycle after being converted to ________.

Answer 2

succinyl CoA

Question 3

Clathrin is a self-associating protein, which is able to form cage-like structures, which facilitate receptor-mediated endocytosis.

Answer 3

True

Question 4

Long-chain fatty acyl-CoAs are transported across the mitochondrial inner membrane using the carrier ________.

Question 5

The shuttle system for transfer of acetyl-CoA generated in the mitochondrial matrix to the cytosol includes:

A) citrate from the citric acid cycle.
B) citrate lyase in the cytosol.
C) the production of NADPH by malic enzyme.
D) ATP hydrolysis.
E) all of the above.

Question 6

Free fatty acids are released from the adipocyte after mobilization of fat stores by:

A) hormone sensitive lipase.
B) monoacylglycerol lipase.
C) adipose triglyceride lipase.
D) lipoprotein lipase.
E) A, B, and C.

Question 7

The reduced cofactor used in fatty acid synthesis is ________.

Question 8

Which of the following statements is FALSE?

A) Chylomicrons are lipoproteins that transport dietary fat from intestine to peripheral tissues.
B) VLDL transports triacylglycerol synthesized in the liver to peripheral tissues.
C) Some fatty acids become complexed with serum albumin for transport in the blood to peripheral cells.
D) LDL is the main form in which cholesterol is transported to tissues.
E) The cholesterol ester content of HDL is generally less than that of chylomicrons.

Question 9

________ is taken up by cells using receptor-mediated endocytosis, which involves the recognition of the B-100 apolipoprotein component of LDL.

Question 10

All of the fatty acid synthase reactions are carried out on substrates attached to acyl carrier protein via a ________ linkage.

Question 11

The overall net synthesis of palmitate starting from acetyl CoA requires:

A) 8 acetyl-CoA, 8 ATP and 16 NADPH and 16H+.
B) 8 acetyl-CoA, 7 ATP and 14 NADPH and 14 H+.
C) 8 acetyl-CoA, 7 ATP and 14 NADPH and 7 H+.
D) 8 acetyl-CoA, 7 ATP and 16 NADPH and 8 H+.
E) 8 acetyl-CoA, 8 ATP and 14 NADPH and 7 H+.

Question 12

________ are formed (primarily in the liver) when acetyl CoA accumulates beyond its capacity to be oxidized or used for fatty acid synthesis.

Question 13

Which of the following statements about β-oxidation of fatty acids is CORRECT?

A) Both dehydrogenation reactions produce a C=C double bond.
B) Both dehydrogenation reactions use FAD as the electron acceptor.
C) Thiolytic cleavage releases acetyl-CoA and a free fatty acid in the final step of the cycle.
D) Fatty acids of any length are oxidized by exactly the same enzymes.
E) All fatty acids must be activated to acyl-CoAs before entering the pathway.

Question 14

The liver is the central organ in animals for processing lipoproteins whether they are derived from the diet or from biosynthetic pathways.

Question 15

Mono- and poly-unsaturated fatty acids are produced in the endoplasmic reticulum by desaturase enzymes.

Question 16

Excess cholesterol is metabolically degraded in the liver.

Question 17

While a number of hormones can stimulate lipolysis, the primary hormonal effects in adipose tissue are mediated by ________ in response to stress and by ________ during fasting.

Question 18

β-oxidation of unsaturated fatty acids yields the same amount of energy as saturated fatty acids with the same number of carbons.

Question 19

Elongation of fatty acids from palmitate occurs only in the mitochondrion.

Question 20

The first committed step in fatty acid synthesis is the formation of ________ in a reaction catalyzed by acetyl CoA carboxylase.

Question 21

HMG-CoA reductase, the major control point of cholesterol biosynthesis is regulated by transcriptional and post-transcriptional mechanisms mediated by Insig proteins bound in the endoplasmic reticulum membrane.

Question 22

Insulin stimulates fatty acid synthesis by which of the following mechanisms?

A) Stimulation of a glucose transport across the plasma membrane
B) Dephosphorylation of acetyl-CoA carboxylase
C) Stimulation of dephosphorylation of pyruvate dehydrogenase
D) Activation of citrate lyase
E) All of the above

Question 23

The prostaglandins, leukotrienes and thromboxanes belong to a family of local acting signaling molecules, all of which are derived from ________ acid.

Question 24

Which of the following compounds is NOT derived from cholesterol?

A) Glycocholate
B) 1,25-dihydroxycholecalciferol
C) α-tocopherol
D) Aldosterone
E) Cortisol