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(Bio)Chemistry Section 1. Which pair of enzymes listed below is unique to gluconeogenesis? a. pyruvate kinase & pyruvate carboxylase b. phosphoenolpyruvate carboxykinase & pyruvate carboxylase c. fructose bisphosphatase & phosphofructokinase d. pyruvate dehydrogenase & glucose-6-phosphatase GLYCOLYSIS Glucose Glucose 6-P Glucokinase /hexokinase GLUCONEOGENESIS Glucose 6-P glucose Glucose-6 phosphatase F-6-P F-1,6-BP Phosphofructokinase F-1,6-BP F-6-P PEP Pyruvate Pyruvate kinase Pyruvate oxaloacetate Pyruvate carboxylase Fructose-1,6-bisphosphatase Oxaloacetate PEP PEP carboxykinase 2. Which two polysaccharides contain the same type of bonds? a. cellulose and amylose b. amylopectin and glycogen c. glycogen and cellulose d. amylose and amylopectin Polysaccharides Carb monomers Starch hydrolyzed Polymer of D-glucose --amylose --amylopectin branches ~12 res. GlycogenD-glucose branches ~8 res Cellulose D-glucose: found in plants β1-4 Inulin bonds α-amylase α1-4 α1-4 & α1-6 α1-4 & α1-6 into glucose, maltose, isomaltose α-amylase cellulase D-fructose: found in roots and tubers of lotus, artichokes and dandilions Dietary Fibers Mixture of polysaccharides and non-carbohydrates 3. Which glycolytic enzyme catalyzes a substrate level phosphorylation? a. glucokinase b. phosphofructokinase c. phosphoglycerate kinase d. hexokinase Enzyme Reaction catalyzed Pathway Molecule generated Phosphoglycerate kinase 1,3-BPG to 3PG Glycolysis ATP Pyruvate kinase PEP to pyruvate Glycolysis ATP Succinyl-CoA synthetase Succinyl-CoA to succinate Kreb’s cycle GTP ATP synthase ADP to ATP ETC ATP Creatine (phospho)kinase Phosphocreatine to Skeletal creatine muscle and brain ATP 4. An example of food that is an excellent source of soluble fiber is a. wheat bran cereal b. brown rice c. whole wheat bread d. oatmeal 5. Which polysaccharide has the highest proportion of α-1,4-glycosidic linkages? a. starch b. amylopectin c. glycogen d. amylose 6. Which sugar is has a C-2 carbonyl carbon? a. fructose b. galactose c. glucose d. mannose GLUCOSE 6 carbon carbohydrates (hexoses) FRUCTOSE Aldoses D-glucose D-galactose D-mannose Ketose D-fructose 7. Which molecule is not essential for the complete degradation of glycogen in muscle and liver? a. inorganic phosphate b. glycogen phosphorylase c. glycogenin d. glycogen debranching enzyme Key enzymes: 1. Glycogen phosphorylase Breaks α14 bonds of glucose in glycogen to form G—1—P 2. Glucan transferase When a glycogen branch has been reduced to 4 residues, it removes 3 and adds to an existing glycogen polymer branch in α14 linkage 3. Debranching enzyme Removes final α16 of last glucose residue from stump to release glucose Glycogenesis Key enzymes: 1. Phosphoglucomutase Isomerizes G—6—P to G—1—P 2. Glycogen synthase Attaches glucose unit (from UDP-Glucose) to an existing primer in α14 3. Branching enzyme a) Removes ~6 glucose chain from growing glycogen polymer b) attaches to a nearby glycogen in α16 Glycogenin: needed for synthesis of glycogen primer (‘glycogenesis’) 8. Which glucose transporter is saturated or close to saturation only after a carbohydrate rich meal? a. GLUT-1 b. GLUT-2 c. GLUT-3 d. GLUT-4 GLUT-1: Passive-facilitative Brain, kidney, placenta, colon, RBCs GLUT-2: Passive-facilitative Liver, pancreatic β cells, kidney Intestineblood (all mono-) GLUT-3: Passive-facilitative Brain, kidney, placenta GLUT-4: ACTIVE Heart, skeletal ms., adipose Insulin-stimulated transporter for active uptake of glucose GLUT-5: Passive-facilitative Intestine For uptake of pentoses For hexoses when [high] 9. Which of the following is NOT considered a reducing sugar? a. glucose b. fructose c. sucrose d. lactose Monosaccharides have free aldehyde and ketone groups 10. What are carbohydrates that consist of long disaccharide repeats and are important components of connective tissue called? a. peptidoglycan b. proteoglycans c. glycogen d. glycosaminoglycans Glycosaminoglycans: polymers of carbohydrate derivatives, especially amino sugars and uronic acids (ex: hyaluronic acid, chondroitin sulfate and heparin sulfate) Peptidoglycan: small peptides with attached GAGs generally structural components of cell walls Proteoglycan: proteins with attached GAGs Glycogen: storage form of glucose in animals 11. Conversion of glucose into carbon dioxide and passage of its electrons to molecular oxygen represents the complete _____ of the sugar a. oxidation b. reduction c. phosphorylation d. destruction Think: “oxidative phosphorylation” (ETC) “β-oxidation” (fats) 12. The action of what enzyme during glycolysis directly produces one molecule of NADH per molecule of substrate a. hexokinase D b. phosphofructokinase-1 c. glyceraldehyde-3-phosphate dehydrogenase d. alpha-ketoglutarate dehydrogenase ATP ADP 13. An abundance of what substance will inhibit some of the enzymes of the citric acid cycle? a. adenosine diphosphate b. acetyl-coenzyme A c. NADH d. glucose Isocitrate ENZYME Citrate Synthase ACTIVATOR INHIBITOR High NAD/NADH High ADP/ATP High ATP/ ADP α-ketoglutarate dehydrogenase CoASH, pyruvate, high ADP/ATP Succinate thiokinase /dehydrogenase Mg2+ Fatty acids, ketone bodies High NADH/NAD Oxaloacetate Isocitrate Dehydrogenase High ATP/ ADP high NADH/NAD 14. What is the major source of energy fuel in the average human diet? a. carbohydrates b. ethanol c. fats d. proteins 55% of kcal 30% of kcal 15% of kcal 15. Starch is the most common digestible polysaccharide in plants and exists mainly as amylose and amylopectin. These polymers are composed of which basic residue? a. D-fructose b. D-galactose c. D-glucose d. D-ribose … and in α1-4 and α1-6 linkages 16. Which of the following forms of dietary fiber is insoluble a. cellulose b. gum c. mucilages d. pectin Dietary Fibers: intrinsic and intact in natural foods. Mixture of un-digestible polysaccharides and noncarbohydrate compounds Cellulose Hemicellulose Pectin Lignin Mucilage Glycoprotein Phytic acid Waxes β14 glucose units Linear D-xylose w/ side chains Soluble polymer of galacuronic acid Methoxy-phenol polymers Sugar acid polymer and galactan mix Extensin is the major form Inositol hexaphosphate, chelating Esters of fatty acids and alcohols 17. The hydrolysis of lactose by lactase produces equimolar amounts of which to monosaccharides? a. fructose and glucose b. fructose and galactose c. galactose and glucose d. glucose and glucose Sugar monomers Maltose Dimer of D-glucose (“glucan”) α1-4 Isomaltose Dimer of D-glucose Sucrose D-glucose & D-fructose Lactose D-glucose & D-galactose bonds hydrolyzed maltase α1-4 α1-2 isomaltase sucrase (invertase) β1-4 lactase Cellobiose Dimer of D-glucose β1-4 cellulase (bacteria) Trehalose Dimer of D-glucose α1-1 trehalase (microbe) 18. Which of the following describes glycogenin? a. it is a protein of muscular glycogen b. it has no enzymatic activity c. it is attached to the nonreductive end of glycogen d. it has an amylo-(1,4-1,6)-transglycosylase activity Used in Glycogenesis Primer to which first glucose residue is attached Has transglycosylase activity But only 1-4 (not 1-6… that’s the branching enzyme) 19. Which of the following describes glycogen? a. it is a heteropolysaccharide b. it is a polymer of alpha-1,4 linked residues with alpha 1-6 branches every 24-30 residues c. it has many more monosaccharide units than starch d. it is a form of stored energy in cytoplasmic vesicles Polysaccharides Carb monomers Starch hydrolyzed Polymer of D-glucose --amylose --amylopectin branches ~12 res. GlycogenD-glucose branches ~8 res Cellulose D-glucose: found in plants β1-4 Inulin bonds α-amylase α1-4 α1-4 & α1-6 α1-4 & α1-6 into glucose, maltose, isomaltose α-amylase cellulase D-fructose: found in roots and tubers of lotus, artichokes and dandilions Dietary Fibers Mixture of polysaccharides and non-carbohydrates 20. Which is true of UDP-glucose a. it is a substrate of UDP-glucose phosphorylase b. it contains one sugar with five carbons and one sugar with six carbons c. it is a substrate of the degradation of glycogen d. it is an allosteric activator of glycogenbranching enzyme UDP-glucose Uridine-5’-diphosphate-glucose Nucleotide Base + ribose + phosphate 5-carbon 6-carbon Glycogen synthase attaches glucose unit (from UDPGlucose) to an existing primer in α14 1. Glycogenesis: biosynthesis of glycogen Key enzymes: 1. Phosphoglucomutase Isomerizes G—6—P to G—1—P 2. Glycogen synthase Attaches glucose unit (from UDP-Glucose) to an existing primer in α14 a) Removes ~6 glucose chain from growing glycogen polymer b) attaches to a nearby glycogen in α16 3. Branching enzyme 21. Which is true of glycogen phosphorylase? a. it is active in its b form (phosphorylase b) b. it is phosphorylated by phosphoprotein phosphatase c. when not phosphorylated, it is activated in the presence of glucose-6-phosphate in the liver d. when phosphorylated, it is inactive in the presence of glucose Phosphorylates Dephosphorylates Glycogen synthase Glycogen phosphorylase Adrenaline / Epinephrine Insulin + — — + Phosphorylates INACTIVE Phosphorylates ACTIVE Dephosphorylates ACTIVE Dephosphorylates INACTIVE 22. Which of the following enzymes represents the step where the second high-energy phosphate is invested in glycolysis? a. pyruvate kinase b. 3-phosphoglycerate dehydrogenase c. phosphofrutokinase d. pyruvate dehydrogenase e. hexokinase hexokinase phosphofructokinase ATP ADP Glyceraldehyde 3-P dehydrogenase Pyruvate kinase Pyruvate dehydrogenase 23. The digestion of starch begins in what location a. in the duodenum with pancreatic amylase b. in the mouth with salivary amylase c. in the jejunum with maltase d. in the colon with absorption of water 24. In the formation of a proteoglycan, which trisaccharide is used to attach the carbohydrates to the protein? a. xylose-galactose-galactose b. rhamnose-galactitol-galactitol c. arabinose-glucose-glucose d. trehalose-fructose-fructose Rhamnose = plant, bacteria Arabinose = plant Trehalose = microbe 25. Which of the following GLUT transporters brings in fructose? a. GLUT-2 b. GLUT-3 c. GLUT-4 d. GLUT-5 GLUT-1: Passive-facilitative Brain, kidney, placenta, colon, RBCs GLUT-2: Passive-facilitative For rapid uptake Liver, pancreatic β cells, kidney Intestineblood (all mono-) GLUT-3: Passive-facilitative Brain, kidney, placenta GLUT-4: ACTIVE Heart, skeletal ms., adipose Insulin-stimulated transporter for active uptake of glucose GLUT-5: Passive-facilitative Intestine For uptake of pentoses For hexoses when [high] 1. Which of the following lipids is NOT found in eukaryotic membranes? a. phosphatidyl inositol b. triglycerides c. cholesterol d. gangliosides Major components of cell membranes 1. Phospholipids (e.g. phosphatidyl inositol) 2. Glycosphingolipids (e.g. cerebrosides and gangliosides) 3. Cholesterol 2. Which of the following is true of Tay-Sachs disease? a. it is provoked by a sphingomyelinase deficiency b. it is transmitted by the mother c. it promotes a specific ganglioside accumulation, mainly in the brain and spleen d. it is an autosomal dominant disease Multiple sclerosis: Lack of phosphoglycerols and sphingolipids in white matter Cholesteryl esters found in white matter CSF has elevated levels of phospholipids Deficiency of GABA Niemann-Pick disease: Deficiency of sphingomyelinase Signs: enlarged liver and spleen, MR, fatal early in life Tay-Sach’s disease: Defect of hexoseaminidase build up of gangliosides Signs: MR, blindness, muscular weakness 3. Which is TRUE of cholesterol a. it is present in prokaryotic membranes b. it has a hydroxyl on its number 3 carbon c. in the serum, it is eliminated by the kidneys d. it is transported in blood by albumin a. it is present in prokaryotic membranes present only in animals b. it has a hydroxyl on its number 3 carbon c. in the serum, it is eliminated by the kidneys Eliminated as bile acids d. it is transported in blood by albumin Lipoprotein (e.g. LDL, HDL) 4. Which of the following is TRUE of chylomicrons a. they are always present in the lymphatic After a meal circulation intestines b. they are synthesized by the liver c. they are enriched in esterified cholesterol triglycerides and free fatty acid d. in the serum, they carry apolipoproteins A, B-48, CII and E 5. Which is TRUE of nascent high-density lipoprotein (HDL) a. it contains lecithin-cholesterol acyl transferase b. it principally functions as storage for C&E apolipoproteins A and E Protein & phospholipid c. it is rich in triglycerides & intestines d. it is synthesized only by the liver 6. If blood plasma levels are extremely high in arachidonic acid, which type of supplement listed would be useful in increasing eicosapentaenoic acid (EPA) and Omega 3s docosahexanoic acid (DHA) levels? a. glucosamine and chondroitin b. B complex with B6, B12 and folate c. cold water fish oil supplement d. ADEK, the fat soluble vitamins 7. Which of the following is the carrier for fatty acids into the inner mitochondria a. CoA b. FAD c. carnitine d. fatty acetyl-CoA Transport of Acyl-CoA into mitochondria using carnitine as a carrier CPT I CPT II 8. Odd chain fatty acid degradation leads to the production of acetyl-CoA and what other compound? a. propionyl-CoA b. malonyl-CoA c. acetoacetyl-CoA d. beta-hydroxybutyrate Acyl-CoA + CoASH + FAD + NAD + H2O Acetyl-CoA + Acyl-CoA + FADH2 + NADH The FADH2 + NADH are further oxidized in the electron transport chain for ATP formation Note: If EVEN # of carbons in fatty acid If ODD # of carbons in fatty acid Acetyl-CoA Propionyl-CoA 9. Which of the following unsaturated fatty acids is one that can be synthesized by the liver a. linoleic acid b. linolenic acid c. oleic acid d. arachidonic acid BAD QUESTION LA and ALA are essential fatty acids AA is ‘conditionally’ essential, meaning that if you don’t get LA or ALA in your diet, you don’t make AA 10. What is the end product of beta oxidation of fatty acids, which feeds into the TCA cycle? a. pyruvate b. oxaloacetate c. alpha-ketoglutarate d. acetyl-CoA End product of glycolysis Intermediates of the Kreb’s cycle 11. Which lipids are NOT charged at physiologic pH a. glycerophospholipids b. cholesteryl esters c. sphingomyelins d. fatty acids Phosphate (PO4-) Phosphate (PO4-) Acid (COOH/COO-) 12. Which molecule is NOT derived from cholesterol? a. vitamin D b. cortisol c. leukotriene A4 d. taurocholate Eicosanoid Stuff made from cholesterol 1. Vitamin D 2. Bile acids 3. Steroids Adrenocorticoids: Glucocorticoids, mineralocorticoids Sex hormones: estrogens, testosterone, progesterone 13. Which condition accelerates the mobilization of fat from adipocytes? a. activation of lipoprotein lipase b. activation of phospholipase A2 c. activation of hormone-sensitive lipase d. activation of acetyl-CoA carboxylase lipoprotein lipase: cleaves lipoproteins (VLDL, chylomicrons) releases triglycerides for tissues phospholipase A2: cleaves phospholipids (and sphinogmyelins) releases fatty acids for eicosanoid synthesis hormone-sensitive lipase: cleaves stored fats (adipocytes) releases fatty acids for gluconeogenesis acetyl-CoA carboxylase: converts acetyl-CoA to malonyl-CoA for fatty acid synthesis 14. Which fatty acid process / cell location is a correct match? a. fatty acid activation / cytosol b. fatty acid oxidation / endoplasmic reticulum c. fatty acid desaturation / nucleus d. fatty acid synthesis / mitochondria Mitochondria ER Cytosol 15. Which condition stimulates the highest rate in the synthesis of ketone bodies? a. feasting b. physical activity c. overnight sleep d. starvation Some get made during normal fasting Glucose stores are consumed More fats get consumed for energy Excess incomplete lipid metabolism results in ketone body production 16. Which of the following foods contain no cholesterol? a. roast beef b. bacon c. ice cream d. baked potato Not an animal product 17. What disease is caused by a genetic defect in the enzyme sphingomyelinase leading to the accumulation of sphingomyelin in the brain, liver, and spleen? a. Niemann-Pick disease b. sudden infant death syndrome (SIDS) c. Tay-Sachs disease d. maple syrup urine disease Niemann-Pick disease: Deficiency of sphingomyelinase Tay-Sach’s disease: Defect of hexoseaminidase build up of gangliosides Signs: enlarged liver and spleen, MR, fatal early in life Signs: MR, blindness, muscular weakness Maple syrup urine disease: Defect in metabolism of branch-chain amino acids Signs: take a wild guess 18. Which of the following is an example of an omega-3 polyunsaturated fatty acid? a. eicosapentaenoic acid, 20:5 (Δ5,8,11,14,17) b. arachidonic acid, 20:4 (Δ5,8,11,14) c. linoleic acid, 18:2 (Δ9,12) d. docosahexanoic acid, 22:4 (Δ7,10,13,16) 19. In the transportation of fatty acids into the mitochondria, fatty acyl-CoA needs a carrier to cross the inner membrane of the mitochondria. What is the name of this carrier? a. creatine b. lipoate c. acetyl-CoA d. carnitine 20. What is the name of the enzyme present in the capillaries of muscle and adipose tissue that is activated by apolipoprotein CII to hydrolyze triacylglycerols to fatty acids and glycerol? a. pancreatic lipase b. lipoprotein lipase c. hormone sensitive lipase d. lingual lipase 21. Which is the best source of oleic acid? a. corn oil b. olive oil c. safflower oil d. soybean oil Exceptions: plant oils with little PUFA Coconut oil High in medium-chain fatty acids C10-C14 Olive oil High in oleic acid, a C18 MUFA C18:1,9 22. Which of the following dietary lipids has the most influence on raising total blood cholesterol levels? Only in conjunction with high kcal a. cholesterol b. saturated fatty acids c. polyunsaturated fatty acids LOWER blood d. monounsaturated fatty acids cholesterol levels 23. Which is the preferred polyunsaturated fatty acid source for the production of the series 3 prostaglandins? a. borage oil b. corn oil c. linseed oil d. salmon oil Omega 6 synthesize series 1 PGs ALA EPA series 3 PGs… but “sluggish” C20:3;8,11,14 (DGLA) ω-6 PG1 LT3 1 3 C20:4;5,8,11,14 (AA) PG2 LT4 PGI2 TX2 2 4 2 2 PG3 LT5 PGI3 TX3 3 5 3 3 ω-6 C20:5,5,8,11,14,17 (EPA) ω-3 24. A high omega-6:omega 1 fatty acid ratio in the diet favors the synthesis of which eicosanoid via the Δ5-desaturase enzyme a. 1-series prostaglandins b. 2-series prostaglandins c. 3-series prostaglandins d. 5-series leukotrienes Associated with normal ω-6 levels via arachidonic acid..see last slide Associated with ω-3 pathways Associated with ω-3 pathways 25. Hydrogenation of polyunsaturated fatty acids produces which of the following products that are particularly artherogenic? a. α-linolenic acids b. cis-fatty acids c. gamma-linolenic acids d. trans-fatty acids Trans versus cis format Sources of trans-fatty acids —Partially hydrogenated margarine, shortening, commercial frying fat, high-fat baked goods, salty snacks 26. Triglycerides consist of three fatty acids attached to a backbone made of which of the following? a. glyceraldehyde b. glycerol c. sphingosine d. glycogen 27. Triglycerides contain more energy per gram than carbohydrates because of what reason? a. they are denser b. they are in a more oxidized form c. they are in a more reduced form d. they are more hydrophobic Energy is released by oxidative processes: β-oxidation, oxidative phosphorylation, glycolysis, Kreb’s 28. Which of the following is a lipid that functions as a chemical messenger at or near the site of its production and is directly derived from arachidonic acid? a. steroid hormone b. prostaglandin c. peptide hormone d. second messenger From cholesterol… act far away Not lipids May be lipids, but not AA 29. Each round of beta oxidation of fatty acids produces one molecule each of which of the following? a. FADH2, NADH, and acetyl-CoA b. FADH2, NADPH, and acetyl-CoA c. FAD, NAD+, and acetyl-CoA d. FAD, NADP+, and acetyl-CoA Acyl-CoA + CoASH + FAD + NAD + H2O Acetyl-CoA + Acyl-CoA + FADH2 + NADH The FADH2 + NADH are further oxidized in the electron transport chain for ATP formation Note: If EVEN # of carbons in fatty acid If ODD # of carbons in fatty acid Acetyl-CoA Propionyl-CoA 30. The reaction catalyzed by which enzyme (the target of statin drugs) is the ratelimiting step in cholesterol synthesis? a. desmolase b. hydroxymethylglutaryl-CoA reductase c. squalene epoxidase d. cyclase Key Regulatory Enzyme: HMG-CoA reductase Decreased activity 1. Fasting 2. Cholesterol 3. Dietary cholesterol 4. Statin (analog drugs of mevalonate) 5. Glucagon and glucocorticoids Increased activity 1. Insulin and Thyroid hormone 1. Which of the following amino acids can be used to produce pyruvate? a. isoleucine b. arginine c. methionine d. serine 2. Which of the following amino acids is the precursor to dopamine? a. tyrosine b. phenylalanine c. lysine d. tryptophan Catechol Catecholamine No longer an amino acid 3. The amino acid alanine can give rise to what compound by transamination? a. phosphoenolpyruvate Glycolysis / gluconeogenesis b. pyruvate c. oxaloacetate Kreb’s cycle intermediates d. fumarate Fate of pyruvate Glucose Pyruvate in liver Post-glycolysis Pre-Kreb’s Acetyl-CoA L-alanine Lactate 4. Which of the following amino acids is the one normally found in globular proteins? a. glutamine b. serine c. tyrosine d. valine amine hydroxyl hydroxyl Polar vs. Non-polar: Non-polar side chains usually get buried in the interior of protein Globular proteins are largely non-polar 5. Which is true of 2,3-bisphosphoglycerate (BPG)? a. it is formed from an intermediate of the pentose phosphate pathway b. its concentration is four times that of hemoglobin c. it weakly attaches to hemoglobin F d. it is not present in the fetus glycolysis equimolar BPG binds deoxyhemoglobin and stabilizes it 6. Which is true of the O2-saturation curve of hemoglobin A? a. it is displaced toward the right in the presence of an increased hydrogen ion (H+) concentration b. it is not influenced by 2,3bisphosphoglycerate (BPG) c. it is a simple hyperbolic curve d. it is influenced by nitrogen (N2) T-form is favored: thus shifting curve Always influenced sigmodal Huh? B. Hemoglobin –continued 4 subunits held by non-covalent bonds 4° structure 2° and 3° structures are also flexible… therefore a variety of factors affect the conformation of Hb LOW: pCO2, [H+], [Cl-], [2,3-bisphosphoglycerate] HIGH: pO2 Opposite R-form binds O2, T-form cannot Cooperative Allosterism: Binding of first O2 takes the longest time… the rest get progressively faster. This is because binding O2 changes conformation of other subunits, facilitating further O2 binding 7. Which amino acid is utilized in the synthesis of serotonin? a. histidine b. phenylalanine c. tryptophan d. tyrosine Histidine histamine Phenylalanine tyrosine catecholamines dopamine norepinephrine epinephrine Tryptophan serotonin 8. Purines are oxidized to the liver to yield which product? a. acetic acid b. oxalic acid c. glutamic acid d. uric acid Purines Hypoxanthine Xanthine Uric acid Gout E1: G6Pase (von Gierke’s) E2: PRPP Synthetase E8: DNase E6: RNase E4: Ribonucleotide reductase E5: HGPTase (Lesch-Nyhan) E7: Xanthine Oxidase (hypouricemia) E4 9. Legumes are an incomplete source of protein because they lack which essential amino acid? a. lysine b. methionine c. threonine d. tryptophan Soybean Nuts Peanut Other Legume - + - + - + - Blank: adequate + + - + High -Low + Gelatin Green leafy veggies Sesame Sunflower seed Grain Cereal - Meat Eggs Dairy - Met Ile Leu Lys Phe Thr Trp Val + + + + + + + - - + EAA 10. alpha helices and beta pleated sheets represent aspects of what structure in proteins? a. primary b. secondary c. tertiary d. quaternary Peptide bond Random coil, beta bending too 3D structure related to function: catalytic site Multiple subunits 11. Which of the following is an exclusively ketogenic amino acid? a. valine b. glycine c. aspartate d. lysine Two purely ketogenic amino acids to remember: Leucine and Lysine 12. Which of the following is a peptide hormone? a. thyroxine b. cortisol c. glutathione d. glucagon Amino Acid derivative Steroid Tripeptide: antioxidant 13. What are the isoflavones in soy protein called? a. genisterin, daidzein, and glycitein Hormones b. estrogen and testosterone Cruciferous veggies c. indoles and isothiocyanates Enzymes d. chymotrypsin and trypsin 14. Which of the following is associated with the presence of edema in kwashiorkor? a. inadequate intake of water b. high plasma albumin levels c. low plasma albumin levels d. excessive intake of dietary protein Kwashiorkor: inadequate protein with adequate kcal. Therefore, decreased protein synthesis (albumin) Therefore, fluid accumulates in third space (edema, ascites) Consequence: Kwashiorkor: “Disease of the first child” Protein-Energy Malnutrition (PEM) Due to chronic protein deficiency Signs/Sx: Weakness, edema, loss of hair, skin lesions, diarrhea, fatty liver, recurrent infections (MCC death is infection). Marasmus: Total deficiency of all ergogenic macronutrients (C, P, F) No edema. Leads to total loss of body mass 15. What is the name of the uncoupler protein present in brown fat mitochondria? a. glycogenin b. thermogenin c. lipogenin d. chymotrypsinogen Brown fat: burned to keep warm (infants and bears!) Instead of using fat for ATP production, the ETC is uncoupled and the energy is released as heat 16. Which amino acid is NOT aromatic? a. tyrosine b. phenylalanine c. histidine d. tryptophan Ring structure, but double bonds are not conjugated These are the only three aromatic amino acids 17. Which of these molecules is the smallest? a. insulin b. glucagon c. glutathione d. myoglobin 51 amino acid protein 29 amino acid protein tripeptide Multiple polypeptide chains: quaternary 18. Which protein is mostly triple-helical and practically insoluble in water? a. elastin b. collagen c. myoglobin d. trypsin Soluble in water Collagen Most abundant protein in the body Mature tropocollagen composed of 3 α-chain subunits 3 subunits held together by H-bonds Different tissues have different amino acid compositions Ex: Type I collagen is two α-1 and one α-2 chain Glycine is the most abundant amino acid in collagen, with lots of proline and lysine 1. What condition applies to an enzymecatalyzed reaction when [S]>Km? a. velocity is half of Vmax b. velocity is directly proportional to [S] c. velocity depends on [E] and [S] d. velocity is near Vmax 2. What is the name of the inactive precursor of a protein that is regulated by proteolytic cleavage? a. phosphatase b. zymogen c. apoprotein d. peptide Enzyme that cleaves off phosphates Protein without ‘prosthetic’ group Any protein with the suffix “ogen” is a precursor that needs to be activated by proteolytic cleavage Ex: trypsinogen 3. The enzyme trypsin is classified as which of the following? a. oxidoreductase b. lyase c. hydrolase d. ligase Break bonds with addition of water IUB Systematic Classification and nomenclature International Union of Biochemistry (IUB) Enzymes are classified into 6 classes according to function: 1. Oxidoreductase Re-dox reactions: A + B=O A=O + B 2. Transferase Transfer groups between substrates 3. Hydrolase Break substrates by addition of water 4. Lyase Break substrates without water 5. Isomerase Convert isomers: AB2 B—A—B 6. Ligase Ligate with new covalent bond: C—C, O, N, S Synthetase: uses ATP/GTP as energy source Synthase: uses other energy 4. Individuals with lactose intolerance are often capable of tolerating small quantities of lactose found in which of these dairy products? a. buttermilk b. ice cream c. milk d. yogurt Made with bacteria, which use lactose for energy 5. In a catalyst reaction by an enzyme, the maximum initial velocity Vmax is which of the following? a. it is achieved when the enzyme is saturated by a substrate b. it is equal to two times the MichaelisMenton constant Km c. it is diminished in the presence of a competitive inhibitor d. it is dependent on the concentration of enzyme utilized 6. Enzymes that utilize coenzymes that are reversibly oxidized and reduced are in what class of enzymes? a. oxidoreductases b. transferases c. hydrolases d. isomerases Coenzymes like: NADH/NAD FAD/FADH2 Also, think “dehydrogenase” 1. Which of the following atoms is added to the structure of T3 and T4? a. selenium b. copper c. iodine d. magnesium T3: tri-iodo-throxine T4: tetra-iodo-thyroxine 2. Which of these enzymes causes release of arachidonic acid from membrane phospholipids? a. phospholipase A2 b. phospholipase A1 c. phospholipase C d. phospholipase D The only phospholipase we care about These guys cleave phospholipids at various locations, releasing different parts 3. Which hormone is derived from an amino acid a. insulin b. epinephrine c. retinoic acid d. calcitriol Peptide hormone: many amino acids Catecholamine: Phenylalanine Tyr Vitamer of vitamin A Vitamer of vitamin D 4. Which is NOT a normal response to insulin? a. increased glycolysis b. increased fatty acid synthesis c. decreased glycogen degradation d. decreased glucose uptake Insulin opposes Glucagon/Epinephrine Increases entry of glucose and neutral amino acids into target cells Increases protein synthesis in skeletal muscle Increases glycolysis (activates glucokinase, PFK-1) Decrease gluconeogenesis (inactivates PEPCK gene) Increases glycogenesis (activates glycogen synthase) Decreases glycogenolysis (inactivates glycogen phosphorylase) Increases lipogenesis (activates acetyl-CoA carboxylase) Decreases lipolysis (inactivates hormone-sensitive lipase) 5. Which of the following is true of Grave's disease? a. it promotes a hypothyroid state in the affected person b. it is provoked by the presence of antibody, which inhibits the TSH receptor c. it is characterized by a weak concentration of serum TSH d. it is characterized by destruction of the thyroid glands IgG antibody stimulates the thyroid Activates the TSH receptor Diffuse hypertrophy of the thyroid gland Uncontrollable production of T3 and T4 In response, the body decreases TSH 6. Which is true of triiodothyronine (T3)? a. it is a peptide hormone b. it is recognized by a membrane receptor on a target cell c. it is elevated in the serum in goiter caused by deiodase deficiency d. at high blood concentrations, it inhibits protein synthesis and produces negative nitrogen balance thyroglobulin Nuclear membrane Deiodase converts T4 to T3 Excessive protein synthesis = positive nitrogen balance 7. Leptin, which functions to decrease appetite, is synthesized in which tissue? a. liver b. adipose tissue c. muscle d. hypothalamus Orexigenic: Peptides that INCREASE appetite Released by Agouti-related peptide Neuropeptide Y Melanin Concentrating Hormone (MCH) Orexins (hypocretins) Insulin Ghrelin Brain Brain Brain Brain Pancreas Stomach Anorexigenic: Peptides that DECREASE appetite Released by Peptide YY: blocks ghrelin Glucagon-like peptide: delays stomach emptying, acts on satiety center in brain Cholecystokinin Melanocortin: binding R inhibits intake Leptin: regulates intake of kcal, C, F, but not percentages of each Does not prevent obesity Intestine Intestine Intestine Brain Adipocyte 8. Glucagon and epinephrine activate adenylyl cyclase present in the adipocyte cell membrane that initiates the intracellular second messenger cascade, which activates which enzyme? a. hormone sensitive lipase b. lipoprotein lipase Two clues: c. pancreatic lipase 1. Adipocyte 2. Glucagon/epinephrine d. lingual lipase 9. The main function of iodine is for the synthesis of which type of hormone? a. catecholamine b. glucocorticoid c. parathyroid d. thyroid Biologically active form of vitamin D 10. Which hormone stimulates calcitriol synthesis in the kidneys? a. aldosterone b. calcitonin c. parathyroid hormone d. thyroxine PTH and calcitonin have opposite effects on Vitamin D synthesis/activation 11. Which of the following hormones will stimulate gluconeogenesis? a. insulin b. glucagon c. aldosterone d. vasopressin Adrenal hormones: Cortisol glucocorticoids gluconeogenesis Aldosterone mineralocorticoids Vasopressin = ADH 12. Hormones can be members of all of the following classes of molecules EXCEPT for which one? a. peptides b. lipids c. carbohydrates d. amino acid derivatives 1. Which is the final degradation product of the purine nucleotides in humans? a. beta alanine b. xanthine c. urea d. uric acid Catabolism by Nucleases: Too much uric acid results in GOUT Purine Nucleotides NH4+ , ribose 1-P, Pi and uric acid Pyrimidine Nucleotides NH4+ , ribose 1-P, Pi, and CO2, acetate, β- ALANINE -aminoisobutyrate E1: G6Pase (von Gierk’s) E2: PRPP Synthetase E8: DNase E6: RNase E5: HGPTase (Lesch-Nyhan) E9 E7: Xanthine Oxidase (hypouricemia) E9: Adenosine Deaminase (SCID) E4 2. Which is a structural difference between DNA and RNA? a. DNA contains thymine instead of uracil b. DNA contains ribose instead of deoxyribose c. DNA contains uracil instead of thymine d. DNA contains guanine instead of cytosine 3. Which is the ring structure in pyrimidine biosynthesis that is placed onto the ribose phosphate using PRPP? a. uracil b. orotate c. cytosine d. thymine E1:Carbamoyl Phosphate Synthetase E2: Aspartate Transcarbamoylase E3: PRPP Synthetase Inhibited by CTP Stimulated by PRPP Inhibited by UTP Inhibited by all mono and diphosphate nts 4. Which of the following is a high-energy intermediate utilized in the salvage of a free nitrogenous base to elevate it to the monophosphate nucleotide level? a. 5'-phosphoribosylamine b. 5'-phosphoribosyl-1'-pyrophosphate c. methenyl-tetrahydrofolate d. formyl-tetrahydrofolate PRPP PPi Hypoxanthine Inosine Monophosphate AMP/GMP PRPP: 5-phosphoribosyl-1pyrophosphate 5. Activated ribose (PRPP) is a key intermediate for the synthesis of nucleotides and some amino acids. Which reaction represents the activation of ribose? a. ribose-1-phosphate + ATP PRPP + AMP b. ribose-2-phosphate + ATP PRPP + AMP c. ribose-3-phosphate + ATP PRPP + AMP d. ribose-5-phosphate + ATP PRPP + AMP 6. Which base is missing in DNA? a. adenine b. guanine c. uracil d. thymine 7. Among the choices below, which one does not play a role in the replication of a bacterial chromosome? a. UTP (uridine 5'-triphosphate) Replicates RNA virus genomes b. reverse transcriptase c. DNA polymerase I d. helicases 8. Regarding E. coli, the proofreading of DNA is performed by what enzyme? a. 3'-5' exonuclease activity of RNA polymerase b. 5'-3' polymerase activity of DNA polymerases I and III c. 3'-5' exonuclease activity of DNA polymerases I, II and III d. 5'-3' exonuclease activity of DNA polymerase III 9. Which sugar is involved in the synthesis of nucleic acids? a. mannose b. galactose c. ribose d. xylose … and 2’-deoxyribose for DNA 10. The synthesis of this nucleotide is derived from vitamin B2 a. DNA b. FAD c. NAD d. RNA Vitamin B2 Vitamin B3 11. What is the name of the linkage (bond) that forms the covalent backbone of DNA and RNA? a. ester linkage b. phosphodiester linkage c. hydrogen bond d. glycosidic bond 5’-phosphate 2’-deoxyribose phosphodiester bond: connects monomers together H 3’-hydroxyl 12. What is the name of the disease that is caused by an elevated concentration of uric acid in the blood and tissues that causes joints to become inflamed, painful and arthritic? Borrelia burgdorferi: fever, headache a. Lyme disease b. gout c. Parkinson's disease Lack of dopaminergic cells, tremors d. rheumatoid arthritis Not due to uric acid 1. A deficiency in which vitamin is associated with bleeding gums? a. vitamin A b. vitamin B6 c. vitamin C d. vitamin D Gingival hemorrhage bowed legs, stunted bone growth, and swollen joints. Infants fed only cow's milk are at risk of developing scurvy, since cow's milk is not an adequate source of vitamin C. periungual hemorrhage Typical rash 2. What vitamin is not an antioxidant? a. vitamin A b. vitamin C c. vitamin E d. vitamin K Antioxidants to know: 1. Vitamin E 2. Vitamin C 3. Vitamin A 4. Selenium 5. glutathione 3. Which of the following iron-containing foods contains the most absorbable form of dietary iron? a. red meat b. pasta c. milk d. spinach Factors Physiologic needs increasing absorption Pregnancy, lactation Growth Phlebotomy Menstruation, chronic bleeding Iron form (e.g. heme, Fe3+) Ascorbic acid (vitamin C) and low pH enhance absorption by favoring Fe2+ over Fe3+ Iron supplements in chelated form (ferrous gluconate, etc) are better than inorganic FeSO4 Best absorbed as heme, as found in hemoglobin and myoglobin 4. What is the RDA for vitamin C? a. 60 mg/day b. 120 mg/day c. 500 mg/day d. 1200 mg/day Not exactly true AI for newborns: 40 mg/day RDA 75 mg/day for females 90 mg/day for males UL for adults: for adults: 2 g/day A daily intake of 200-300 mg would saturate the blood (1.2-1.5 mg/dL) Excess excreted in urine 5. Which of the following is a disease marked by accumulation of copper in the liver, brain, kidneys and eye? a. Menke's disease b. hemochromatosis c. goiter d. Wilson's disease Copper deficiency Iron excess Excess or deficency of iodine 6. What is the recommended daily intake for sodium? a. 1000 mg/day b. 2400 mg/day c. 5000 mg/day d. 10,000 mg/day Not exactly true AI Adults: 3.8 grams of table salt (1 tsp) 1.5 g of Na 2.3 g Cl UL: 5.8 grams of table salt Regularly consume salt in excess of UL More than 90% of American and Canadian men More than 75% of American and 50% of Canadian women 7. The dietary precursor in mammals of coenzyme A is which of the following? a. pyridoxine b. niacin c. biotin d. pantothenic acid Anti-pernicious anemia factor Vitamin B1 FMN Vitamin B2 Pyridoxamine Riboflavin Nicotinic acid TPP CoASH Methylcobalamin Biotin Anti-pellagra factor Thiamin Vitamin Form Biologically Active Form (BAF) Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B7 Vitamin B9 Vitamin B12 Vitamin C Pantothenic acid Vitamin B1 H4-folate Vitamin B2 Niacinamide Dehydroascorbic acid 5’-deoxyadenosylcobalamin Vitamin Form FAD NADP Anti-beriberi factor Pantetheine Folacin Pyridoxal phosphate Biologically Active Form (BAF) Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B7 Vitamin B9 Vitamin B12 Vitamin C 8. Which is true of thiamine (vitamin B1) a. it is a lipid soluble vitamin b. it is necessary in humans because a deficiency can cause pellagra c. it is a coenzyme that participates in oxidative decarboxylation of alpha-keto acids d. it is made up of two nitrogen bases, two sugars and two phosphates ADEK B3 FAD 9. Tetrahydrofolate is a coenzyme that permits the transfer of what substances? a. amine groups b. CO2 (or bicarbonate) c. monocarbon groups other than CO2 d. multicarbon groups Folate and tetrahydroflate are for METHYL transfer 10. Which vitamin is NOT required for the function of the pyruvate dehydrogenase complex? a. thiamine Note: This complex may b. niacin simply be called “pyruvate dehydrogenase” c. pyridoxine d. pantothenic acid Pyruvate Acetyl CoA Keys to remember: Coenzymes are required for this sequential and coupled rxn Thiamine (vitamin B1)Thiamine PyroPhosphate i. TPP ii. Lipoate Cofactor for many aerobic reactions justifies it as a dietary supplement iii. CoASH Obviously … Gets oxidized (derivative of Vit B5) iv. FAD derived from riboflavin (vitamin B2) required for electron transfer v. NAD+ Nicotinamide adenine dinucleotide, derived from niacin (vitamin B3) 11. Niacin deficiency is associated with which disease? a. rickets b. pellagra c. xeropthalmia d. scurvy Vitamin D Vitamin A Vitamin C Don’t forget the 3 Ds: Dementia, diarrhea, dermatitis 12. The RDA for what mineral in women of child-bearing age is more than double the RDA for men? a. calcium b. magnesium c. zinc d. iron Newborn 0.27 mg/day Adult males 8 mg/day Adult females 19-50 18 mg/day Adult females 51+ 8 mg/day Pregnancy 27 mg/day 13. Phylloquinones and menaquinones are natural forms of which vitamin? a. vitamin A b. vitamin D c. vitamin E d. vitamin K cholecalciferol 14. In what organ does the enzymes alpha-1-hydroxylase hydroxylate vitamin D3 (cholecalciferol) to its fully active hormonal form? a. liver b. kidney c. pancreas d. intestines hydroxylation 25-hydroxy-cholecalciferol hydroxylation 1,25-dihydroxy-cholecalciferol 15. Which of the following foods is a good source of provitamin A carotenoids? a. pears b. roast beef c. cantaloupe d. cauliflower Think yellow or orange 16. Which vitamin / mineral pair is essential for glycolysis? a. riboflavin / calcium b. niacin / magnesium c. niacin / calcium d. riboflavin / magnesium Know your vitamins: B2 – FAD B3 - NAD Rule of thumb: Whenever ATP is involved think Mg2+ 17. The pyruvate dehydrogenase complex catalyzes the conversion of pyruvate to acetyl-CoA in mitochondria. Which vitamin is NOT needed for this reaction? a. thiamine b. pantothenate c. pyridoxine d. riboflavin Know your vitamins! B1, B2, B3 and B5 are required 18. Which condition / vitamin deficiency is NOT a correct match? a. night blindness / vitamin A b. hemolysis / vitamin D Hemolysis / vitamin E c. hemorrhage / vitamin K Rickets (osteomalcia) / vitamin D d. pellagra / niacin 1. What makes enzymes effective catalysts? a. they increase the energy released during a reaction b. they increase the activation energy required for a reaction c. the decrease the equilibrium of the reaction d. they decrease the activation energy required for a reaction TRANSITION STATE 2. What type of reversible inhibitor competes with the substrate for the active site of the enzyme? a. noncompetitive inhibitor b. competitive inhibitor c. uncompetitive inhibitor d. mixed inhibitor Competes for active site All other inhibitors bind to sites other than the active site 3. For this reaction, AB, the ΔG’˚= 5.7 kJ/mol at 25˚C. Which is the correct equilibrium? a. [B] = [A] b. Keq = 100 c. [B] > [A] d. 10[B] = [A] Not enough information was given, therefore impossible to know. (However, I seriuosly doubt this will be asked on Boards) 4. Which is a characteristic of a near-equilibrium cellular reaction? a. Keq and Q differ by several orders of magnitude b. ΔG is large and negative c. the reaction is potentially a regulatory point d. the reaction is reversible Keq: equilibrium constant at standard (in vitro) conditions Q: equilibrium constant at steady-state (in vivo) conditions Regulatory points: tightly regulated therefore nowhere near Large negative ΔG: spontaneous and fast 5. A cereal breakfast bar containing 3g fat, 2 g protein, and 30g of carbohydrates has approximately how many calories? a. 140 b. 150 c. 155 d. 290 Atwater Carbs: Protein: Fat: coefficients: 4 kcal/g 4 kcal/g 9 kcal/g (3x9) + (2x4) + (30x4) = 27 + 8 + 120 = 155 6. Which vitamin-derived nucleotide is NOT involved in energy production within the Kreb's cycle or electron transport chain? a. NADPH b. FMN c. FAD d. NAD Fatty acid, cholesterol and DNA synthesis 7. Biochemical reactions are considered to be reversible if their ΔG'˚ is which of the following? a. large and positive b. large and negative c. close to zero d. equal to delta H˚' 8. A biochemical reaction taking place in a healthy human with a large positive ΔG can proceed in the forward direction only if which of the following is TRUE? a. it is catalyzed by an enzyme b. it is coupled with a reaction with a larger negative ΔG c. the temperature is increased d. the activation energy is lowered A little bit of a trick question: (what’s missing) 9. The functional electron transport systems can be formed in vitro from purified components of the respiratory chain and vascular membranes. Assuming the presence of O2, succinate, ubiquinone (UQ), cytochrome c, and complexes III and IV, the final electron acceptor is which of the following? a. succinate b. complex III c. complex IV d. H2O According to the question, it could pass to complex IV Not an electron acceptor Complex I Complex III Complex IV Complex II 10. Which of the following is TRUE of the Kreb's cycle? a. it is implicated in the synthesis of glucose from acetyl-CoA b. it can function equally well aerobically and anaerobically c. it requires pyridoxal phosphate and lipoic acid for its activity d. it is inhibited by an elevated intracellular level of ATP, NADH and citrate ENZYME ACTIVATOR INHIBITOR Citrate Synthase High NAD/NADH High ATP/ ADP Isocitrate Dehydrogenase High ADP/ATP High ATP/ ADP high NADH/NAD α-ketoglutarate dehydrogenase CoASH, pyruvate, high ADP/ATP Fatty acids, ketone bodies High NADH/NAD Oxaloacetate Succinate thiokinase Mg2+ /dehydrogenase 11. The passage of a high-energy phosphate from one organic structure to another and facilitated by an enzyme is given what term? a. oxidative phosphorylation b. oxidase phosphorylation c. redox phosphorylation d. substrate-level phosphorylation Enzyme Reaction catalyzed Pathway Molecule generated Phosphoglycerate kinase 1,3-BPG to 3PG Glycolysis ATP Pyruvate kinase PEP to pyruvate Glycolysis ATP Succinyl-CoA synthetase Succinyl-CoA to succinate Kreb’s cycle GTP ATP synthase ADP to ATP ETC ATP Creatine (phospho)kinase Phosphocreatine to creatine Skeletal muscle ATP and brain 12. The majority of the energy conserved in the TCA cycle is by the harvesting of which of the following? a. high-energy phosphates b. high-energy esters c. high-energy thioesters d. high-energy electrons …as NADH and FADH2