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26 Cards in this Set
- Front
- Back
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Linoleate and alpha-linoleate are "essential fatty acids" because...
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mammals cannot introduce more than one double bond in fatty acid chains.
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which of the following is TURE about fatty acid synthase of vertebrates?
A- It generates NADPH B- It has a flexible phosphopantetheine arm C- It is a complex of seven polypeptides D- Its principal product is stearate. |
B
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the fatty acid synthase of vertebrates is a single large ________ that contains all seven enzymatic activities needed to synthesize and cleave the fatty acid. The portion of this large polypeptide that has an acyl carrier protein (ACP)-like activity contains a 4-phosphopantetheine prosthetic grop that serves as a ________ arm, tethering and growing fatty acyl chain to the surface of the fatty acid synthase complex and carrying the reaction intermediates from one enzyme active site to the next.
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polypeptide
flexible |
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In animal cells, where does fatty acid synthesis occur?
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in the cytosol.
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what is the rate-limitng step in fatty acid synthesis?
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the formation of malonyl-CoA.
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the conversion of acetyl-CoA to malonyl-CoA, which is catalyzed by ________ _________, is the rate-limiting step in the biosynthesis of fatty acids. the irreversible formation of malonyl-CoA commits acetyl-CoA for use in fatty acid biosynthesis, while malonyl-COA itself shuts down ______, thus preventing a _____ cycle in which fatty acid synthesis and beta-oxidation occur simultaneously.
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acetyl-CoA carboxylase
Beta-oxidation futile |
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How does aspirin reduce inflammation?
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It inhibits the formation of prostaglandins.
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Asprin irreversibly inactivates the cyclooxygenase activity of cyclooxygnease by acetylating a ____ residue and blocking the enzyme's active site, thus inhibiting the conversion of __________ to prostaglandins and thromboxanes
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ser
Arachidonate |
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squalene, the 30 carbon precursor of cholesterol, is composed of...
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six isoprene units.
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All sterols are...
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alcohols
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what lipoprotein participates in reverse cholesterol transport?
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HDL
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ordinarily, cholesterol is transported from the liver (via ____ and then _____ to extrahepatic tissues. In reverse cholesterol transport, depleted _____ transports cholesterol from extrahepatic tissues to the liver
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VLDL, LDL
HDL |
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which of the following is TRUE about glycerophospholipids?
A- They have a hydrophobic head group B- They have a head group joined by a phosphodiester linkage C- They are used as fuel D- They are derived from tiacylglycerols |
B
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Which of the following occurs when cholesterol enters cells?
A- cholesterol is released from LDL particles when the particles become internalized by lysosomes B- LDL receptors on the cell surface recognize cholesterol in LDL particles C- The internalized LDL receptor is degraded to amino acids that can be recycled into new proteins D- The apoB-100 protein in LDL particles does NOT get internalized |
A
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The binding of cholesterol-containing LDL particles to an LDL receptor on the cell surface initiates endocytosis, which brings ______ and its _____ into the cell within an endosome
the ndosome eventually fuses with a lysosome, which contains enzymes that hydrolyze the cholesteryl esters, releasing cholesterol and fatty acids into the cytosol. |
LDL
receptor |
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What is the function of eicosanoids?
A- they serve as pigments B- They are hormones C- they are signaling molecules D- they are membrane lipids |
C
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which of the following occurs during the first cycle of fatty acid chain synthesis?
A- The malonyl group from malonyl-CoA is transferred to the acyl carrier protein (ACP) B- The malonyl group is transferred to the acetyl group C- Malonyl-CoA is decarboxylated as it is transferred to the acyl carrier protein (ACP) D- The acetoacetyl-ACP formed in the condensation step is transferred from the acyl carrier protein (ACP) to beta-ketoacyl synthase (KS) |
A
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Malonyl CoA-ACP transferase of the fatty acid synthase complex trasnfers the ______ group from malonyl-CoA to the unoccupied phosphopantetheine -SH group of ____. Once ACP is charged with the malonyl group, condensation of the activated acetyl and malonyl grops takes place, resulting in the formation of _______________
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malonyl
ACP acetoacetyl-ACP |
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In animals, what is the source of acetyl-CoA used in fatty acid synthesis?
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citrate
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fatty acyl-CoA desaturase, which introduces a double bond in a saturated fatty acid is what type of enzyme?
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mixed-function oxidase
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fatty acyl-CoA desaturase is a type of oxidase known as a mixed-function oxidase. It is an oxidase because it catalyzes _______ in whcih molecular oxygen is the electron acceptor, but oxygen atoms do NOT appear in the oxidized product. Furthermore, it is a mixed-function oxidase because it oxidizes two different substrats, the ______ _____ and ________, simultaneously.
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oxidations
fatty acid NADPH |
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Which of the following is TRUE about triacylglycerols?
A- They are derived from phosphatidic acid B- They are stored predominantly in the liver C- The vast majority of fatty acids released from triacylglycerols are used as fuel D- they are soluble in blood |
A
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Triacylglycerols, which consist of three fatty acids linked to glycerol, are derived from phosphatidic acid which consists of two fatty acids linked to _______ ______. The phosphate group from phosphatidic acid is hydrolyzed to form 1,2-diacylglycerol.
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glycerol 3-phosphate
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Which of the following lipids or lipid-derived molecules has a glycerol backbone?
A- sphyingomyelin B- cerebroside C- estrogen D- plasmalogen |
D
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which of the following is TRUE about the regulation of triacylglycerol metabolism/
A- Glucagon promotes the synthesis of triacylglycerols B- People with severe diabets mellitus fail to synthesize fatty acids from carbs C- stimulation of glyceroneogenesis in the liver leads to a decrease in the synthesis of triacylglycerols D- Insulin promotes the mobilization of fatty acids. |
B
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Chylomicrons
A- are synthesized in the small intestine B- principally carry cholesterol C- are apolipoproteins D- are the smallest of the lipid carriers |
A
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