QUIZ #4 LIPID STRUCTURES AND METABOLISM

  1. Which of the following is an essential fatty acid?

a. Linoleic

b. Oleic

c. Propionic

d. Lauric

e. Arachidic

  1. What happens to the numbering of an unsaturated fatty acid when its length is increased by elongation?

a. The "delta" number of each carbon increases

b. The "omega" number of each carbon increases

c. Both 1) and 2) are correct

d. Neither 1) nor 2) are correct

  1. If a 20:0 fatty acid is desaturated, elongated and desaturated again, the resulting fatty acid would be:

a. 22:2 delta 11,14

b. 22:2 omega11

c. 22:2 delta8,11

d. Both 1) and 2) are correct

e. Both 2) and 3) are correct

  1. What is the basic unit of cholesterol and ßcarotene?

a. Isoprene units

b. Fatty acids

c. Glycerol

d. Methylmalonyl~CoA

  1. Which of the following saturated acids has the highest melting point?

a. Formic acid

b. Butyric acid

c. Palmitic Acid

d. Arachidic acid

  1. In humans, which fatty acid is a DIRECT precursor for prostaglandin synthesis?

a. 18:2 omega9

b. 22:6 omega3

c. 20:4 omega6

d. 18:2 omega6

e. 18:3 omega6

  1. Which of the following is true about cardiolipin?

a. It is found in the inner membrane of mitochondria

b. It consists of 4 fatty acids, 2 phosphates and 2 glycerols

c. Is most similar to the sphingolipids called gangliosides

d. Can only be found in cardiac tissue

e. All of the above are true

  1. Which enzyme is inhibited by cortisol?

a. Prostaglandin synthase

b. Prostaglandin reductase

c. 5Lipoxygenase

d. Phospholipase A2

e. Phospholipase C

  1. All of the following consist of isoprene units EXCEPT:

a. Vit E

b. CoQ

c. PAF

d. Vit K

e. Dolichols

  1. A fatty acid that is 18:2 is:

a. Linoleic

b. Oleic

c. Palmitic

d. Arachidic

e. Arachidonic

  1. Which of the following is FALSE concerning the insertion of double bonds in a fatty acid by a desaturase enzyme?

a. Will not desaturate "deeper" than C9 from the COOH end

b. Can form either cis or trans double bonds

c. Second double bond cannot form distal to (from the delta end) to an existing double bond

d. A second double bond is added with a methylene interruption

  1. Which statement regarding lipids is TRUE?

a. Plasmalogens are examples of sphingolipids

b. Phosphatidyl serine can be converted in one step to phosphatidyl choline

c. Phosphatidyl choline is the most abundant membrane phospholipid

d. Phospholipids are randomly associated with the inner and outer layers of membranes

e. Phospholipids are easily "flipflopped" across membranes

  1. Which of the following enzymes is NOT present in adipocytes?

a. Phosphofructokinase

b. Phosphoglycerate kinase

c. Pyruvate kinase

d. Glycerol kinase

e. Hormone sensitive lipase

  1. Which of the following is NOT associated with ßoxidation of fatty acids?

a. Uses NAD and FAD

b. Occurs in the mitochondrion of the cell

c. Uses invididual enzymes rather than an enzyme complex

d. Acyl~Carrier Protein is the carrier of the acyl~ group

  1. Which of the following is NOT true of ßoxidation : fatty acid synthesis?

a. Mitochondrial : Cytosolic

b. acetyl~CoA: malonyl~CoA

c. Hydration : Dehydration

d. Free Enzymes : Enzyme Complex

e. NADPH : FADH2

  1. HMG~CoA redutase is inhibited by:

a. Cholesterol

b. Glucagon

c. Both

d. Neither

  1. Identify the forms of the nucleotides used in ßoxidation and fatty acid synthesis, respectively.

a. FAD; NADH

b. NADP; NADPH

c. NADPH; FAD

d. FAD; NADPH

e. NAD; NADH

110.You have two 6carbon compounds; one is glucose and the other is caproic acid (6:0). If both are complexely oxidized to CO2 and H2O, what is the ratio of their potential maximum ATPs generated?

a. Glucose yields 38 ATP where as caproic acid yields 28 ATP

b. Glucose yields 28 ATP where as caproic acid yields 38 ATP

c. Glucose yields 36 ATP where as caproic acid yields 38 ATP

d. Glucose yields 38 ATP where as caproic acid yields 44 ATP

e. Glucose yields 38 ATP where as caproic acid yields 46 ATP

  1. Which of the following stimulates HDL synthesis?

a. Lecithin

b. A sedentary lifestyle

c. LCAT and ACAT

d. Moderate alcohol intake

e. Leptin

  1. Which of the following allosterically activates acetyl~CoA carboxylase?

a. Citrate

b. ATP

c. AMP

d. Glucagon

e. Palmityl~CoA

  1. What is the key regulatory enzyme for fatty acid synthesis?

a. Malate Dehdyrogenase

b. Malic Enzyme

c. Citrate Cleavage Enzyme

d. Acetyl~CoA carboxylase

e. Pyruvate Carboxylase

  1. Fatty acid synthesis occurs:

a. In the cytosol

b. On a large enzyme complex

c. Under wellfed conditions

d. Under the positive influence of insulin

e. All of the above are correct

  1. Which of the following statements regarding the regulation of serum cholesterol is FALSE?

a. Ingestion of cholestyramine resin increases cholesterol excretion

b. Cholesterol is degraded to CO2 and H2O

c. HMG~CoA reductase is a membrane bound enzyme

d. Most of our cholesterol is converted into bile salts and acids

e. The carbons in cholesterol can be traced to carbohydrates

  1. Which of the following conversions between phospholipid groups does NOT take place?

a. PE > PC

b. PC > PE

c. PS > PE

d. PA > PC

e. PC > Sph

  1. Lecithin plays an important role in the transfer of cholesterol between:

a. Chylomicrons and VLDLs

b. VLDLs and IDLs

c. IDLs and LDLs

d. LDLs and HDL3s

e. LDLs and peripheral tissues

  1. The mobilization of triacylglycerol bound fatty acids from adipose tissue and their subsequent oxidation by muscle mitochondria require all of the following EXCEPT:

a. serum albumin

b. carnitine

c. acetyl~CoA carboxylase

d. hormone sensitive lipase

e. fatty acyl~CoA synthetase

  1. Apoprotein CII acts to:

a. stimulate lipoprotein lipase

b. activate LCAT

c. facilitate LDL uptake

d. inhibit hormone sensitive lipase

e. convert LDL's into HDL's

  1. What is the function of ApoCII?

a. Activation of the LCAT enzyme

b. Attaches LDL to its receptor

c. Mediates the delivery of cholesterol to peripheral tissues

d. Activation of lipoprotein lipase

e. Inhibition of hormone sensitive lipase

  1. Which of the following enzymes is NOT used in fatty acid synthesis beginning with citrate?

a. kinase

b. reductase

c. dehydratase

d. thiolase

e. lyase

  1. The addition of radioactively labeled 14CO2 to a cell that is actively synthesizing fatty acids will appear in the final fatty acid product.

a. True

b. False

  1. If acetyl~CoA is 14C radioactively labeled in both of its carbons and it is add to a cell that is actively synthesizing fatty acids, the radioactivity will appear ______in the final product.

a. in every carbon

b. in every other carbon

c. only in the two carbons at the omega end

d. in every carbon EXCEPT the two at the omega end

e. only in the two carbons at the delta end

  1. In which form are most lipids transferred out of the intestinal mucosal cells into the lymphatic system?

a. Free fatty acids

b. 2Monoacylglycerols

c. Chylomicrons

d. Micelles

e. Free triglycerides

  1. Which of the following statements is (are) TRUE?

a. HMG~CoA > mevalonate is the regulatory step in cholesterol biosynthesis

b. Synthesis of cholesterol begins with the condensation of two acetyl~CoA's in the cytosol

c. Glucagon ultimately leads to decreased HMG~CoA reductase activity

d. Cytosolic NADH is a cosubstrate for HMG~CoA reductase

a. a), b) and c) are true

b. a) and c) are true

c. b) and d) are true

d. d) only is true

e. all (ad) are true

  1. Which leucotriene is responsible for smooth muscle contraction during anaphylactic shock?

a. LTA4

b. LTB4

c. LTC4

d. LTD4

e. LTE4

  1. What is the function of ApoB100?

a. activate lipoprotein lipase

b. transport HDL3 out of the liver

c. activates LCAT

d. facilitates the uptake of LDL by peripheral tissues

e. none of the above are correct