NUT 455 TEST 3
Most Americans consume approximately half of their total dietary lipid as triacylglycerols, and the other half as cholesterol; very little is taken in as phospholipids.
F Dietary fat is mostly TAG (>90%); cholesterol together with phospholipids represent ~5%.
Once a micelle, containing lipids and lipid-soluble compounds, enters the enterocyte, it is referred to as a chylomicron.
F Explanation: A micelle delivers the FAs, etc. to the enterocyte, where they are taken up, reesterified to TAG by the enterocyte, and repackaged into a new lipoprotein called the CM.
Bile is the GI enzyme that hydrolyzes dietary triacylglycerol into free fatty acids and glycerol.
F Explanation: Bile is not an enzyme; a lipase enzyme, especially pancreatic lipase, does this.
Fatty acids are converted into glucose by gluconeogenesis and used for energy during starvation.
F Explanation: FAs cannot be used to increase net glucose. During starvation, FAs are broken down to acetyl-CoA and ketones to be used to produce energy.
Ketogenesis is the synthesis of ketone bodies from fatty acids for energy under conditions of excess glucose, such as in the fed state.
F Explanation: Ketogenesis occurs when CHO levels are low.
Adipocytes' primary function is to store fat as triacylglycerol; thus, they do not require glycolysis and the TCA cycle for energy needs.
F Explanation: Adipocytes are like all cells in that they require energy, and thus need glycolysis and the TCA cycle to produce ATP.
The conversion of linoleic acid (18:2) to arachidonic acid (20:4) involves the addition of 2 carbons to the methyl end and 2 double bonds at the n-3 and n-6 positions of the omega end.
F Explanation: The addition of 2 carbons is at the carboxylic acid end and double bonds are placed no closer to the methyl carbon than the 9th carbon from the carboxylic acid end.
Essential fatty acids are classified as such because we cannot synthesize them from other fatty acids and they are required for the synthesis of prostaglandins, thromboxanes, and leukotrienes
T
HMG-CoA reductase is a key enzyme in the synthesis of cholesterol from acetyl-CoA.
T
One of the primary functions of a phospholipid is possible because of its structure, which allows it to be both hydrophobic and hydrophilic.
T
The key organ in clearing (i.e., breaking down) lipoproteins is the liver.
T
Unlike long-chain fatty acids, short-chain fatty acids from the diet leave the enterocyte via the portal vein and go directly to the liver.
T
Carbamoyl aspartate can only be used for _____ synthesis. a. pyrimidine b. purine c. urea d. creatine
a
Cholesterol serves as a precursor for all of the following EXCEPT _____. a. phospholipids b. estrogens and androgens c. bile acids d. vitamin D
a
During starvation, or when following a very-low-carbohydrate diet, the consumption of alcohol may cause hypoglycemia. Which of the following is NOT a contributing factor? a. Alcohol breakdown depletes NADPH. b. Alcohol breakdown favors the reduction of DHAP to glycerol-3-phosphate. c. Alcohol breakdown diminishes formation of alpha-ketoglutarate. d. Alcohol breakdown creates a high NADH:NAD ratio.
a
Lp(a) is a genetic variant of _____; its presence _____ a genetic predisposition to heart disease. a. LDL, increases b. HDL, decreases c. LDL, decreases d. HDL, increases
a
Proinflammatory cytokines such as tumor necrosis factor are atherogenic because they a. attract blood monocytes into the intima. b. oxidize membrane fatty acids. c. absorb cholesterol readily to become foam cells. d. delay clotting of platelets, which narrows the lumen, restricting blood flow.
a
The HDL accomplishes its function in reverse cholesterol transport in two ways. Choose the phrase that does NOT describe one of these. a. increased apoC-2 activity to reduce its triacylglycerol content b. increased activity of LCAT on vascular endothelial cells c. increased activity of transferring cholesterol to other lipoproteins d. using its apoE component to bind to LDL receptors
a
What are some products of the reaction catalyzed by pancreatic lipase? a. 2-monoacylglycerols, free fatty acids b. free fatty acids, glycerol, cholesterol c. 2-monoacylglycerols, free fatty acids, phospholipids d. free fatty acids, glycerol, cholesteryl esters
a
What is the carrier molecule needed for mitochondrial membrane transport of long-chain fatty acids and their CoA derivatives? a. carnitine b. creatine c. creatinine d. cysteine
a
What is the most important unsaturated fatty acid serving as a precursor for eicosanoid synthesis? a. arachidonic acid b. palmitoleic acid c. oleic acid d. erucic acid
a
What is the primary mechanism for regulation of amino acids in excess of need for synthesis of protein, providing about 50% of the liver energy needs after a meal? a. oxidation b. decarboxylation c. phosphorylation d. hydrogenation
a
Which apolipoprotein is key to the delivery of triacylglycerol to tissues? a. apo-C2 b. apoA-1 c. apoE d. apoB-100
a
Which enzyme will act on corn oil in the small intestine? a. pancreatic lipase b. lecithin cholesterol acyl transferase c. cholesterol esterase d. lipoprotein lipase
a
Which group of 20-carbon fatty acid derivatives can exhibit either pro-arrhythmic or anti-arrhythmic physiological actions in the body? a. prostaglandins b. thromboxanes c. leukotrienes d. sterols
a
Which hormone is considered to be an antagonist of lipolysis? a. insulin b. epinephrine c. glucagon d. thyroxine
a
Which of the following is a nitrogen-containing, non-protein compound that performs an important function in the body? a. glutathione b. methionine c. pepsin d. actin
a
Why might someone who is drunk have high blood lactate levels? a. High levels of NADH produced by ADH shift the direction of the lactate dehydrogenase reaction. b. High levels of NADH produced by the MEOS stimulate lactate dehydrogenase activity. c. Consuming calorie-yielding compounds and not providing enough oxygen to cells increases anaerobic respiration. d. Reducing equivalents inhibit the synthesis of lactic acid and increase the synthesis of acetaldehyde.
a
Zwitterions are amino acids that have no net electrical charge because a. their side chains are not charged. b. they migrate to a neutral place in an electrical field. c. they are essential/indispensable. d. they have an amino group in their side chain.
a
he fatty acid structure below is an omega-_____ fatty acid called _____. CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH a. 3, linolenic b. 6, linoleic c. 6, eicosapentaenoic d. 9, oleic
a
A high rate of ethanol ingestion causes an _____. a. increase in gluconeogenesis b. increase in fatty acid synthesis c. increase in protein breakdown d. increase in glycogen synthesis
b
Carbon-carbon double bonds in the trans form a. result in a kinking of the fatty acid into a U-shape. b. extend the fatty acid into a linear shape. c. are required to create saturated fatty acids. d. are the hallmark of essential fatty acids.
b
Choose the correct sequential order for participants in lipid digestion. a. colipase, pancreatic lipase, bile, micelles b. bile, colipase, pancreatic lipase, micelles c. bile, enterokinase, colipase, micelles d. micelles, bile, pancreatic lipase, colipase
b
Glycerophosphatides serve which of the following functions? a. source of stored energy b. constituent of cell and organelle membranes c. precursor for long-chain n-3 fatty acids d. constituent of myelin sheaths
b
How does orlistat reduce absorption of dietary fat? a. by replacing dietary fat with a synthetic, indigestible substitute b. by inhibiting the activity of pancreatic lipase c. by binding free fatty acids and causing their excretion d. by inhibiting HMG-CoA reductase
b
If you were deficient in vitamins B6 and B12 and had high blood levels of homocysteine, what dietary substance could remove some of the homocysteine by donating a methyl group to form methionine? a. biotin b. betaine c. serine d. creatine
b
In general, most amino acids are absorbed from the a. stomach. b. duodenum and jejunum. c. ileum. d. colon.
b
In response to excess dietary carbohydrate and chylomicron remnants, the liver synthesizes _____ to transport triacylglycerol. a. chylomicrons b. VLDLs c. LDLs d. HDLs
b
In the small intestine, which enzyme hydrolytically activates a pancreatic zymogen so that lipid digestion can occur? a. pepsin b. trypsin c. colipase d. maltase
b
In what form is most body fat stored? a. fatty acids b. triacylglycerols c. cholesterol d. phospholipids
b
Name the genetic disease associated with the lack of the liver enzyme necessary to convert phenylalanine to tyrosine. a. maple syrup urine disease b. phenylketonuria c. homocystinuria d. lactase deficiency
b
Reverse cholesterol transport that removes cholesterol from peripheral cells and returns it to the liver is carried out by _____. a. LDL b. HDL c. VLDL d. lipoprotein lipase
b
Thromboxane A2 is a hormone-like substance made from: a. stearic acid. b. arachidonic acid. c. palmitic acid. d. myristic acid.
b
Undigested lipid in the stomach creates satiety because it a. speeds the rate of emptying of the stomach. b. delays the rate of emptying of stomach contents. c. enhances gastric motility. d. suppresses GIP and secretin.
b
What antithrombotic n-3 fatty acid is found in fish oil? a. alpha-linolenic b. eicosapentaenoic c. arachidonic d. stearic
b
What dietary fatty acid family exerts anti-thrombotic properties? a. n-6 b. n-3 c. n-9 e. saturated
b
When fatty acids are completely oxidized the end products are: a. fatty acid and glycerol. b. carbon dioxide, energy, and water. c. urea and acetate. d. carbon, hydrogen, and phosphate
b
Which amino acids are metabolized mostly in skeletal muscles? a. those with side chains containing aromatic rings b. those with side chains that are branched c. those with side chains containing basic groups d. those with side chains containing sulfur atoms
b
Which of the following lipoproteins are normally NOT present in blood in the fasting state? a. VLDL b. chylomicrons c. LDL d. HDL
b
Which regulatory peptides in the pancreatic phase of digestion activate the release of brush-border enzymes such as enteropeptidase? a. trypsinogen and trypsin b. cholecystokinin and secretin c. carboxypeptidase A and B d. elastin and chymotrypsin
b
Which three amino acids cannot undergo transamination to an appreciable extent, making provision of their alpha-keto acids ineffective in lowering blood nitrogen concentrations in kidney disease patients? a. leucine, isoleucine, valine b. lysine, threonine, histidine c. valine, tryptophan, phenylalanine d. methionine, cysteine, phenylalanine
b
These neutral lipids are transported from the liver to the adipose tissues by lipoproteins called 39._____, whose signal apolipoprotein is 40._____. a. LDLs b. VLDLs c. chylomicrons a. B-100 b. B-48 c. A-1
b, a
A diet rich in simple sugars increases the hepatic formation of de novo fatty acids and the neutral lipids called 31._____ from glucose. a. cholesterol b. phospholipids c. triacylglycerols
c
A function of hydrochloric acid in gastric juice during protein digestion is a. to neutralize the acidity of the stomach. b. to inactivate pepsinogen by suppressing pepsin formation. c. to denature the quaternary, tertiary, and secondary structures of protein. d. to cleave peptide bonds.
c
All of the following are functions of apolipoproteins EXCEPT: a. stimulating enzymatic reactions that regulate the metabolic functions of lipoproteins. b. stabilizing circulating lipoproteins in the blood. c. decreasing the density of the lipoprotein. d. conferring specificity for recognition by receptors on cells.
c
Choose the best description of the action of bile. a. Bile hydrolyzes ester bonds of the triacylglycerols. b. Bile anchors into dietary lipid so that pancreatic lipase can act. c. Bile emulsifies dietary lipid to increase its surface area. d. Bile digests the ester bond of the dietary cholesteryl ester
c
Choose the correct order of enzyme activities in protein digestion. a. tripeptidases, carboxypeptidasea, pepsin, free amino acids b. trypsin, pepsin, collagenase, dipeptidases c. pepsin, trypsin, carboxypeptidases, dipeptidases d. trypsinogen, enteropeptisdase, dipeptidase, chymoptrypsin
c
Choose the list of molecules that would be found in a micelle. a. vitamin A (retinol), glycerol, 2-monoacylglycerols, linolenic acid b. glycerol, butyric acid, cholesterol, 2-monoacylglycerols c. linolenic acid, 2-monoacylglycerols, cholesterol, vitamin D d. fructose, glucose, glycerol, vitamin A
c
Gastric lipase is important for the suckling infant for all of the following reasons EXCEPT: a. It can readily penetrate milk fat globules without bile salt stabilization. b. It hydrolyzes short-chain fatty acids from the sn-3 position. c. It requires an alkaline environment for optimal activity. d. It is highly stable in an acid environment.
c
Phospatidylinositol is a membrane phospholipid that can _____. a. anchor surface proteins to the plasma membrane b. create 2 second messengers in cell signaling c. both a and b d. none of the above
c
Polymolecular aggregates called micelles are small enough to _____. a. enter the enterocytes b. stabilize circulating lipoproteins in the blood c. enter the intramicrovillus spaces to interact with the brush border d. confer specificity for recognition by receptors on cells
c
Sphingomyelins are important phospholipids found in the _____. a. pacemaker of the heart b. kidney tubules c. myelin sheath of nerves d. human blood groups A, B and O
c
The key to the cell's internalization of LDL is the interaction between the receptors and _____. a. cholesterol acyltransferase b. HMG-CoA reductase c. apolipoprotein B-100 d. apolipoprotein C-100
c
The structure below is a _____. a. triacylglycerol b. cholesteryl ester c. phospholipid d. glycolipid
c
Trans unsaturated fatty acids are now considered more atherogenic than saturated fatty acids because they a. are unnatural and only formed during fat processing. b. cause excess blood clotting. c. elevate serum LDL while decreasing HDL. d. were found to cause sudden cardiac arrest in women.
c
Using, 2 high-energy bonds, arginosuccinate synthetase joins aspartate and citrulline to produce arginosuccinate in the cytosol. This is the rate-limiting step in _____ synthesis. a. pyrimadine b. purine c. urea d. creatine
c
What are two major components implicated in the mechanism of atherogenesis? a. growth factors and HDL b. enterocytes and endothelial cells c. inflammation and serum lipids d. primarily VLDL and IDL
c
What is formed when fatty acids are oxidized in the mitochondria (i.e., what is the end product of beta-oxidation)? a. glycerol b. pyruvate c. acetyl-CoA d. triacylglycerol
c
What is the most common lipid characterized by a four-ring core structure found in animals? a. prostaglandins b. leukotrienes c. cholesterol d. glycolipids
c
What is the normal product of the fatty acid synthase system? a. triacylglycerol b. myristate c. palmitate d. butyrate
c
What organ provides the major site for lipoprotein formation from exogenously derived lipids? a. pancreas b. adipose tissue c. intestine d. liver
c
What organ serves as the primary site of amino acid metabolism? a. kidney b. muscles c. liver d. neuropeptides
c
When the diet is lacking in the amino acids lysine and threonine a. proteins will be made without one amino acid. b. the body will synthesize them. c. protein synthesis will be limited. d. another amino acid will be substituted so that synthesis is uninterrupted.
c
Which fatty acid is considered essential and must be supplied by the diet? a. arachidonic acid b. omega-9 fatty acid c. linoleic acid d. oleic acid
c
Which of the following amino acids is ketogenic? a. glycine b. alanine c. leucine d. aspartate
c
Which of the following amino acids represent the branched-chain amino acids found in systemic circulation? a. glycine, alanine, threonine b. phenylalanine, tyrosine, tryptophan c. valine, leucine, isoleucine d. arginine, lysine, histidine
c
Which of the following is NOT a neurotransmitter? a. acetylcholine b. serotonin c. insulin d. epinephrine
c
Which of the following lipoproteins is the major carrier of cholesterol to tissues for use in construction of membranes or steroid hormones? a. VLDL b. HDL c. LDL d. chylomicrons
c
Which of these enzymes is the primary system for oxidizing alcohol after 1 drink? a. catalase b. microsomal ethanol oxidizing enzyme c. alcohol dehydrogenase d. aldehyde carboxylase
c
Abnormal LDL receptors fail to remove cholesterol from the bloodstream, resulting in _____. a. suppression of acyl-CoA cholesteryl acyl transferase (ACAT) b. suppression of hydroxymethylglutaryl-CoA (HMG-CoA) reductase c. hypertriglyceridemia d. familial hypercholesterolemia
d
All of the following are required for fat digestion EXCEPT _____. a. pancreatic lipase b. colipase c. bile d. lysolecithin
d
Arterial fatty steaks are formed primarily due to a. platelet aggregation at the endothelium. b. smooth muscle proliferation. c. toxicity of oxidized LDL to endothelial cells. d. accumulation of foam cells filled with cholesterol.
d
During protein digestion, peptides are broken into free amino acids mainly a. in the mouth. b. in the stomach. c. at the brush border. d. within the enterocyte.
d
Ketogenesis would be the HIGHEST: a. after a high-CHO meal. b. after a high-protein meal. c. after a high-fat meal. d. during prolonged starvation
d
Ketones are produced from: a. cholesterol. b. hormones. c. amino groups. d. acetyl-CoA.
d
Purine degradation results in the formation of xanthine and creation of _____ by xanthine oxidase. a. polyamines b. gout c. citric acid d. uric acid
d
Serotonin is made from which amino acid? a. tyrosine b. niacin c. threonine d. tryptophan
d
The fatty acid chains found in foods and body tissues range from _____ carbon atoms in length. a. 1 to 3 b. 2 to 6 c. 3 to 12 d. 4 to 24
d
The process by which bile salts are absorbed in the ileum and return to the liver is called _____ of the bile salts. a. micelle induction b. resecretion c. conjugation d. enterohepatic circulation
d
The product(s) of pepsin's action is/are _____. a. disaccharides b. amylose c. short-chain fatty acids d. hydrolyzed proteins
d
Three important enzymes remove ammonia from body cells. One is carbamoyl phosphate synthestase I. The other two are: a. branched-chain alpha-keto acid dehydrogenase and phenylalanine hydroxylase. b. alanine aminotransferase and aspartate aminotransferase. c. glutaminase and threonine dehydratase. d. glutamate dehydrogenase and glutamine synthetase.
d
Thromboxanes that activate blood platelets are _____. When EPA is used to synthesize the thromboxane, it is _____. a. vasodilators, a vasoconstrictor b. pro-aggregatory, less pro-aggregatory c. anti-inflammatory, pro-inflammatory d. pro-aggregatory, anti-aggregatory
d
Triacylglycerols with saturated fatty acids of longer chain length tend to be _____ at room temperature. a. liquid oils b. emulsified c. non-esterified fats d. solid fats
d
Urea synthesis occurs partly in the mitochondria and partly in the cytosol of the _____. a. glomeruli b. tubules c. enterocytes d. hepatocytes
d
What is considered the toxic level of blood ethanol? a. less than 10 mg/dL b. 11 to 24 mg/dL c. 25 to 45 mg/dL d. 50 to 80 mg/dL
d
When the amino group has been removed from an amino acid, the carbon skeleton or α-keto acid may be used in many different ways. Which of the following is NOT a possible fate for the carbon skeleton? a. conversion to glucose b. oxidation for energy c. production of ketone bodies d. synthesis of creatine
d
Which drug therapy is associated with reduced cholesterol synthesis in the liver? a. insulin b. niacin c. gene therapy d. HMG-CoA reductase inhibitors
d
Which level of organization determines the final form of a protein molecule consisting of several polypeptide chains? a. primary b. secondary c. tertiary d. quaternary
d
Which of the choices listed below is NOT a reaction of the hepatocyte to an excess amount of free cholesterol? a. increase ACAT activity to store cholesterol b. decrease HMG-CoA reductase activity c. down-regulate the apoB-100/E receptors d. decrease LPL activity
d
what is the carrier for medium-chain fatty acids in portal circulation? a. triacylglycerides b. cholesterol c. chylomicrons d. albumin
d
