Deck 9: Lipid Biosynthesis

Question 1

At what position in fatty acids can mammals introduce double bonds?

A)D1
B)D3
C)D6
D)D9

Answer 1

D

Question 2

Which of the following is NOT a characteristic of arachidonic acid?

A)It contains 5 cis double bonds.
B)It is a precursor of leukotrienes and most prostaglandins.
C)It is an omega-6 fatty acid.
D)It can be synthesized from linoleic acid in mammals.

Answer 2

A

Question 3

Which enzyme catalyzes the formation of malonyl-CoA,the committed step in fatty acid biosynthesis?

A)fatty acid synthase
B)pyruvate carboxylase
C)propionate carboxylase
D)acetyl-CoA carboxylase

Answer 3

D

Question 4

What is/are the main source(s)of NADPH for fatty acid biosynthesis?

A)TCA cycle
B)oxidative phosphorylation
C)malic enzyme and the pentose phosphate pathway
D)glycolysis

Question 5

What type of linkage occurs between ACP and the intermediates in fatty acid biosynthesis?

A)ester
B)thioester
C)amide
D)ether

Question 6

Which of these enzymes is NOT involved in fatty acid synthesis?

A)b-ketoacyl-ACP synthase
B)b-ketoacyl reductase
C)b-hydroxyacyl dehydratase
D)thiolase

Question 7

Which group is similar to the "business end" of CoA in acyl carrier protein?

A)biotin
B)phosphoadenosine
C)pyridoxal phosphate
D)phosphopantetheine

Question 8

Which product is formed in E.coli when b-hydroxydecanoyl-ACP is dehydrated by b-hydroxydecanoyl thioester dehydrase,and subsequently elongated further?

A)acetoacetyl-ACP
B)palmitoleoyl-ACP
C)butyryl-ACP
D)crotonyl-ACP

Question 9

Which of these statements regarding phosphorylation of acetyl-CoA carboxylase is correct?

A)Phosphorylation causes activation only in the presence of palmitoyl-CoA.
B)Phosphorylation is a result of insulin binding to its receptor.
C)High [citrate] inhibits the phosphorylated form.
D)Phosphorylation causes separation of the polymeric form of the enzyme to inactive protomers.

Question 10

Which modification of the regulatory sites on acetyl-CoA carboxylase decreases the affinity for citrate,and increases the affinity for fatty acyl-CoAs?

A)hydroxylation
B)myristoylation
C)phosphorylation
D)glycosylation

Question 11

Which of the following is NOT a characteristic of acetyl-CoA carboxylase?

A)competitive inhibition by palmitoyl-CoA
B)biotin carboxylase and transcarboxylase subunits
C)biotin carboxyl carrier protein subunits
D)citrate shifting the enzyme toward the active polymer

Question 12

Which of the following is NOT a feature of fatty acid elongation?

A)addition of acetyl-CoAs
B)uses both NADH and NADPH
C)requires ATP and biotin
D)uses CoA rather than ACP

Question 13

Which compound is derived from acetyl-CoA in the mitochondria and then transported out to the cytosol?

A)butyrate
B)pyruvate
C)citrate
D)malonate

Question 14

What are the coenzymes of acetyl-CoA carboxylase?

A)biotin and ATP
B)pyridoxal phosphate and TPP
C)NADH and FAD
D)TPP and folic acid

Question 15

Which of the following does NOT regulate acetyl-CoA carboxylase in animals?

A)allosteric stimulation by citrate
B)phosphorylation by protein kinase A
C)allosteric inhibition by palmitoyl-CoA
D)allosteric stimulation by ATP

Question 16

Which enzymes transform reducing equivalents derived from glycolysis in the form of NADH into NADPH?

A)malate dehydrogenase and malic enzyme
B)succinate dehydrogenase and malic enzyme
C)glyceraldehyde-3-phosphate dehydrogenase and malate dehydrogenase
D)succinate dehydrogenase and malate dehydrogenase

Question 17

Which of the following is NOT a characteristic of stearoyl-CoA desaturase?

A)requires NADH and O₂
B)produces a trans double bond
C)involves cytochrome b5 reductase
D)involves cytochrome b5

Question 18

Which enzyme catalyzes the following reaction?
Citrate + ATP + CoA à acetyl-CoA + OAA + ADP + Pᵢ

A)malate dehydrogenase
B)citrate synthase
C)pyruvate carboxylase
D)ATP-citrate lyase

Question 19

Which of the following is NOT a feature of fatty acid synthase?

A)It occurs in cytosol.
B)All the enzymes are on separate polypeptides.
C)It has acyl carrier protein-linked intermediates.
D)It uses NADPH for oxidoreductase reactions.

Question 20

Which enzyme catalyzes the formation of acetoacetyl-ACP?

A)b-ketoacyl-ACP synthase (KSase)
B)acetyl-CoA carboxylase
C)acetyl transacylase
D)b-ketoacyl reductase

Question 21

Which of the following is NOT a characteristic of eicosanoids?

A)They are derived from steric acid.
B)They exert their effects at very low concentrations.
C)They usually act very near their site of synthesis.
D)They include prostaglandins,thromboxanes,and leukotrienes.

Question 22

Which of these lipids does NOT have a sphingosine backbone?

A)ganglioside GM1
B)sphingomyelin
C)phosphatidylinositol
D)cerebroside

Question 23

Which hormone promotes the activation of acetyl-CoA carboxylase?

A)insulin
B)arachidonic acid
C)testosterone
D)estradiol

Question 24

Which of the following compounds is correctly paired with its effect upon fatty acid synthesis?

A)palmitoyl CoA: activates
B)glucagon: activates
C)insulin: inhibits
D)citrate: activates

Question 25

What is the primary site,but not the only site,of cholesterol synthesis?

A)intestine
B)muscle
C)liver
D)adipose tissue

Question 26

What important mechanism can initiate arachidonate release and eicosanoid synthesis?

A)insulin release
B)glucagon release
C)tissue injury
D)platelet formation

Question 27

What enzymatic step is NOT involved in the synthesis of mevalonate from acetyl-CoA?

A)formation of 3-hydroxy-3-methylglutaryl-CoA
B)b-ketothiolase-catalyzed condensation
C)formation of acetyl-CoA
D)HMG-COA reductase activity

Question 28

Which component is NOT a part of plasmalogen biosynthesis?

A)CDP-ethanolamine
B)fatty acyl-CoA
C)long-chain alcohol
D)glycerol

Question 29

Which enzyme is NOT used to catalyze reactions in the synthesis of phosphatidic acid from glycerol and dihydroxyacetone?

A)glycerol kinase
B)glyceraldehyde-3-phosphate dehydrogenase
C)acyldihydroxyacetone-P reductase
D)glycerol-3-phosphate acyltransferase

Question 30

Which of the following is NOT a characteristic of COX-2 inhibitors?

A)can non-selectively block inflammation mediated by both isoforms of COX
B)are NSAIDs
C)have less potential for stomach lesions than aspirin
D)have less renal toxicity than COX-1 inhibitors

Question 31

Which of the following does NOT affect the regulation of fatty acid synthesis in humans?

A)malonyl-CoA binding to carnitine acyltransferase and inhibiting available substrate for ?-oxidation
B)acyl-CoAs as inhibitors of acetyl-CoA carboxylase
C)insulin receptor binding maintaining acetyl-CoA carboxylase in the inactive form
D)glucagon promoting phosphorylation and inactivation of acetyl-CoA carboxylase

Question 32

Which compound in eukaryotes can phosphatidic acid be directly converted into?

A)triacylglycerols
B)acylglycerols
C)monoacylglycerols
D)diacylglycerols

Question 33

In which position is sphinganine acylated?

A)1-OH
B)3-OH
C)2-NH₂
D)3-NH₂

Question 34

Which compound is NOT synthesized from CDP-diacylglycerol precursors?

A)phosphatidylethanolamine
B)phosphatidylglycerol
C)cardiolipin
D)phosphatidylinositol

Question 35

Which of the following is NOT a feature of aspirin?

A)It inhibits the activity of prostaglandin endoperoxide synthase (COX).
B)It stimulates ring opening in prostaglandin synthesis.
C)It acetylates the serine in the active site of the cyclooxygenase (COX).
D)It is classed as a non-steroidal anti-inflammatory drug (NSAID).

Question 36

What are the carbons of sphinganine derived from?

A)palmitate and glycerol
B)arachidonate and glycine
C)fatty alcohol and dihydroxyacetone phosphate (DHAP)
D)palmitate and serine

Question 37

Which of these enzymes catalyzes the committed step in cholesterol biosynthesis?

A)HMG-CoA synthase
B)mevalonate kinase
C)HMG-CoA reductase
D)squalene monooxygenase

Question 38

Which mechanism does NOT regulate HMG-CoA reductase activity?

A)Low [cholesterol] increases mRNA for HMG-CoA reductase.
B)High [cholesterol] increases half-life for HMG-CoA reductase.
C)High [cholesterol] results in lower mRNA for HMG-CoA reductase.
D)Phosphorylation by cAMP cascade inactivates HMG-CoA reductase.

Question 39

Which compound displays dramatic ability to dilate blood vessels and to cause aggregation of platelets?

A)cholesterol
B)platelet-activating factor
C)estradiol
D)arachidonic acid

Question 40

Which enzyme releases arachidonates from 20-carbon fatty acids?

A)phospholipase A1
B)phospholipase A2
C)phospholipase C
D)phospholipase D

Question 41

Which of these hormones is an intermediate on the biosynthetic pathway from cholesterol to both male and female hormones?

A)aldosterone
B)testosterone
C)estradiol
D)progesterone

Question 42

Which lipoprotein has the highest density?

A)chylomicrons
B)HDL
C)LDL
D)VLDL

Question 43

Which of the following is NOT a characteristic of bile salts?

A)They are made by the liver and utilized in the intestine.
B)They insert well into membranes because they are strictly non-polar.
C)They are conjugates of bile acids with glycine and taurine.
D)They are highly effective as detergents.

Question 44

Which of the following is NOT a characteristic of desmolase?

A)It produces cholic acid.
B)It is found in mitochondria of adrenal glands.
C)It has 2 hydroxylase activities.
D)It utilizes cytochrome P-450.

Question 45

What is the series of drugs known as "statins" used for?

A)to inhibit fatty acid synthesis in diet drugs
B)to inhibit squalene monooxygenase
C)to inhibit HMG-CoA reductase
D)to lower cholesterol levels

Question 46

Which of the following is NOT a characteristic of HDL?

A)High HDL correlates with high risk of cardiovascular disease.
B)HDL has a life span of 5-6 days.
C)Returns cholesterol and cholesterol esters to liver.
D)Accumulates cholesterol esters via LCAT action.

Question 47

Which of the following is NOT a characteristic of mixed-function oxidases?

A)They usually involve cytochrome P-450.
B)They often catalyze hydroxylation reactions on ring systems,such as sterols.
C)They use both NADPH and O₂.
D)One of their products is CO₂.

Question 48

Which compound is NOT an intermediate between mevalonate and squalene?

A)geranyl pyrophosphate
B)isopentenyl pyrophosphate
C)pyridoxal phosphate
D)farnesyl pyrophosphate

Question 49

Which lipoprotein particle is generated by the action of lipoprotein lipase on VLDL particles?

A)HDL
B)cholesterol esters;LDL
C)chylomicron
D)triacylglycerol

Question 50

Which of the following is correctly paired with its precursor?

A)cholesterol palmitic acid
B)arachidonic acid prostaglandins
C)testosterone progesterone
D)aldosterone cholic acid

Question 51

Which hormone has been implicated in male baldness,prostate hyperplasia,and prostate cancer?

A)cortisol
B)stanozolol
C)dihydrotestosterone
D)cholesterol

Question 52

Which of the following is NOT a characteristic of squalene?

A)It requires an insoluble protein activator.
B)It is bound to the endoplasmic reticulum (ER).
C)It uses FAD and NADPH.
D)It requires O₂.

Question 53

Which of the following is NOT a property of progesterone?

A)It is produced from pregnenolone in ER.
B)It is synthesized in the adrenal cortex activated by ACTH.
C)It prepares the uterus for attachment of a fertilized ovum.
D)It is secreted from corpus luteum early in the menstrual cycle.

Question 54

Which of these lipoproteins is NOT correctly defined?

A)chylomicron: transporter of dietary lipids to the liver
B)HDL: scavenger of extrahepatic cholesterol
C)LDL: transporter of cholesterol to extrahepatic tissue
D)VLDL: transporter of triacylglycerols from the liver

Question 55

Which receptors are absent or dysfunctional in the genetic disorder of familial hypercholesterolemia?

A)adrenergic receptors
B)insulin receptors
C)HDL receptors
D)LDL receptors

Question 56

Which components constitute the core of lipoproteins?

A)proteins and triacylglycerols
B)triacylglycerols and cholesterol esters
C)phospholipids and cholesterol esters
D)cholesterol esters and proteins

Question 57

Which of the following is NOT an action of cortisol?

A)stimulation of gluconeogenesis and glycogen synthesis in liver
B)inhibition of protein synthesis and stimulation of protein degradation in muscle
C)promotion of allergic and inflammatory responses
D)exertion of an immunosuppressive effect and inhibition of wound healing

Question 58

What is the major circulatory complex for cholesterol and cholesterol esters ("bad cholesterol")?

A)chylomicron
B)HDL
C)LDL
D)VLDL

Question 59

Which lipids are "packaged" in the intestine for transport in the blood stream?

A)chylomicrons
B)HDLs
C)LDLs
D)VLDLs