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Biochemistry
| Question | Answer |
|---|---|
| 1. Fat soluble vitamins 2. Only water soluble vitamin stored in body. Where is it stored? | 1. A, D, E, K 2. B12; stored in liver |
| Deficiency results in: 1. Vitamin A 2. Vitamin B1 | 1. night blindness 2. thiamine deficiency: Beriberi and Wernicke-Korsakoff |
| Describe the two variants of beriberi? | 1. Dry beriberi: muscle wasting and neuropathy 2. Wet beriberi: neuropathy + cardiac failure (dilated cardiomyopathy) |
| 1. Diarrhea, dermatitis and dementia 2. What is the vitamin deficiency? 3. Which inherited disorder has a similar presentation? | 1. Pellegra 2. Vitamin B3 - niacin 3. Hartnup disease (↓ tryptophan absorption) |
| Which vitamin deficiency results in: 1. Wernicke-Korsakoff 2. megaloblastic anemia 3. megaloblastic anemia with neurologic symptoms | 1. Vitamin B1 (thiamine) 2. Folic acid 3. Vitamin B12 |
| Two actions of vitamin B12 | 1. conversion of homocysteine to methionine 2. conversion of methylmalonyl-CoA to Succinyl-CoA |
| Which vitamin deficiency results in: 1. Rickett's in children; osteomalacia in adults 2. Hemolytic anemia, ataxia, peripheral neuropathy 3. Easy bruising and poor wound healing | 1. Vitamin D 2. Vitamin E (similar to B12) 3. Vitamin C |
| Vitamin K deficiency 1. Prothrombin time 2. bleeding time 3. How does vitamin C deficiency differ? | 1. increased PT 2. normal bleeding time 3. normal PT, increased bleeding time |
| 1. Mechanism of Disulfuram 2. Mechanism of Fomepizole | 1. inhibits acetaldehyde dehydrogenase 2. inhibits alcohol dehydrogenase |
| 1. Malnutrition problem resulting in skin lesions, edema and fatty liver 2. What is the fatty liver due to? | 1. Kwashkior - protein malnutrition 2. ↓ apolipoprotein B100 which mediates VLDL secretion from liver |
| Malnutrition resulting in tissue and muscle wasting, loss of subcutaneous fat | Marasmus - Protein and carbohydrate malnutrition |
| Cell site of: 1. fatty acid oxidation 2. fatty acid synthesis 3. glycolysis 4. TCA cycle | 1. mitochondria 2. cytoplasm 3. cytoplasm 4. mitochondria |
| Hexokinase vs Glucokinase 1. inhibition 2. affinity to glucose 3. tissue location 4. activation | Hexokinase 1. feedback inhibition by G6P 2. high affiniy 3. most cells Glucokinase 1. no inhibition 2. low affinity 3. liver 4. insulin |
| First step in glycolysis | conversion of glucose to glucose 6 phosphate by hexokinase/glucokinase |
| Three causes of vitamin B3 deficieny | 1. Hartnup (↓ tryptophan absorption) 2. malignant carcinoid syndrome (↑ tryptophan metabolism) 3. isoniazide (↓ vitamin B6) |
| Peripheral neuropathy and dermatitis from isoniazide usage is due to: | B6 deficiency |
| 1. Where is vitamin D hydroxylated? 2. What role does PTH have in vitamin D metabolism? | 1. liver and kidney 2. PTH induces 1α-hydroxylase in kidney |
| Why does ethanol cause hypoglycemia? | 1. alcohol and acetaldehyde dehydrogenase cause ↑NADH/NAD+ ratio in liver 2. ↑NADH diverts pyruvate to lactate and OAA to malate inhibits gluconeogenesis |
| When energy (ATP) levels in a cell are adequate, what inhibits the following: 1. glycolysis 2. pyruvate dehydrogenase 3. TCA cycle | 1. ATP inhibits PFK1 and pyruvate kinase 2. acetyl CoA 3. ATP inhibits isocitrate dehydrogenase |
| 1. Why can't fat be used to gluconeogenesis? 2. Role of biotin | 1. pyruvate dehydrogenase in irreversible 2. cofactor for carboxylation enzymes (pyruvate carboxylase, acetyl coA carboxylase) |
| If ATP is high in the liver after a meal, PFK1 is inhbited. How do hepatocytes overcome this inhibition to continue producing acetyl CoA for storage? | insulin stimulated PFK2 to produce F-2,6BP which overrides the inhibition of PFK1 and causes glycolysis to proceed |
| What are the rate-determining enzymes: 1. glycolysis 2. gluconeogenesis 3. TCA cycle 4. glycogen synthesis | 1. PFK1 2. Fructose-1,6-bisphosphatase 3. isocitrate dehydrogenase 4. glycogen synthase |
| What are the rate-determining enzymes: 1. glycogenolysis 2. HMP shunt 3. De novo pyrimidine synthesis 4. De novo purine synthesis | 1. glycogen phosphorylase 2. G6P dehydrogenase 3. carbamoyl phosphate synthetase II 4. glutamine PRPP amidotransferase |
| What are the rate-determining enzymes: 1. Urea cycle 2. fatty acid synthesis 3. fatty acid oxidation 4. ketogenesis 5. cholesterol synthesis | 1. carbamoyl phosphate synthetase I 2. acetyl-CoA carboxylase 3. Carnitine acyltransferase I 4. HMG-CoA synthase 5. HMG-CoA reductase |
| Which enzymes does Vitamin B1 (thiamine) serve as cofactor for? | 1. pyruvate dehydrogenase 2. α-ketoglutarate dehydrogenase 3. transketolase 4. branched-chain AA dehydrogenase |
| Which 5 cofactors are necessary for pyruvate dehydrogenase? | "Tender Loving Case For Nancy" 1. Thiamine 2. Lipoic acid 3. CoA (B5, pantothenate) 4. FAD (B2, riboflavin) 5. NAD (B3, niacin) |
| Which enzymes are involved in pyruvate metabolism: 1. alanine → pyruvate 2. pyruvate → oxaloacetate 3. pyruvate → acetyl CoA 4. pyruvate → lactate | 1. ALT 2. pyruvate carboxylase 3. pyruvate dehydrogenase 4. lactate dehydrogenase |
| 1. What does cyanide bind in cells? 2. What does carbon monoxide bind? 3. What is the treatment for cyanide? | 1. Fe3+ of ETC complex 4 2. Fe2+ of heme groups 3. nitrites convert hemoglobin to methemoglobin (Fe3+) which bind cyanide in the blood before reaching tissues |
| What is the Cori cyce? | 1. glucose → pyruvate → lactate in skeletal muscle and RBCs 2. Lactate converted back to glucose in hepatocytes |
| Enzyme deficiency when Fructose-1-phosphate accumulates in hepatocytes | Fructose intolerance; aldolase B deficiency |
| Benign syndrome in which a defective enzyme results in fructose in the blood and urine. | Essential fructosuria; fructokinase deficiency |
| What is the overall role of glucose-6-phosphate dehydrogenase in detoxifying free radicals. | 1. G6PD produces NADPH 2. NADPH reduces glutathione 3. glutathione detoxifies free radicals and peroxides |
| Accumulation of galactose substances results in development of cataracts, hepatosplenomegaly and mental retardation. | Galactosemia; absence of galactose-1-phosphate uridyltransferase |
| Mild condition of galactose metabolism resulting in infantile cataracts. | Galactokinase deficiency |
| 1. Enzyme responsible for sorbitol accumulation in tissues? 2. Which tissues are most effected? | 1. aldose reductase 2. schwann cells, lens, retina and kidneys |
| Liver or kidney dysfunction 1. ↑ BUN 2. ↓ BUN 3. Hyperammoniemia | 1. kidney 2. liver 3. liver amino acid catabolism generates NH4+ which is converted to urea in the liver and excreted by the kidneys |
| 1. Increased phenylalanine in newborn 2. What are the two possible causes cause? | 1. phenylketonuria 2. ↓ phenylalanine hydroxylase or dihydrobiopterin → phenylalanine buildup and deficiency in tyrosine |
| 1. Dark connective tissue, black urine upon standing? 2. What is the deficient enzyme? | 1. alkaptonuria 2. homogentisic acid oxidase necessary to degrade tyrosine to fumarate |
| 2 causes of homocysteinuria | 1. cystathionine synthase 2. hemocysteine methyltransferase deficiency |
| 1. Blocked degradation of branched amino acids 2. What enzyme is deficient? | 1. maple syrupe urine disease 2. α-ketoacid dehydrogenase |
| Hereditary defect in excretion of basic amino acid results in kidney stones. | cystinuria - defective transport of cysteine, ornithine, lysine, and arginine in the PCT of kidneys |
| 1. Which enzyme mediates glycogenolysis? 2. How does insulin regulate this enzyme? | 1. glycogen phosphorylase 2. insulin stimulates protein phosphatase which inactivates glycogen phosphorylase and inactivates glycogen phosphorylase kinase |
| Severe fasting hypoglycemia, elevated liver glycogen, hepatomegaly. | Von Gierke's disease; Glucose-6-phosphatase deficiency |
| Glycogen storage disease resulting in cardiomegaly and systemic findings leading to early death | Pompe's disease; lysosomal α-1,4-glucosidase deficiency (acid maltase) |
| Glycogen storage disorder with painful muscle cramps and myoglobinuria with strenuous exercise. | McArdle's disease; skeletal muscle glycogen phosphorylase deficiency |
| Hepatosplenomegaly, glucocerebroside accumulations. | Gaucher's disease; β-glucocerebrosidase |
| Child with progressive neurodegeneration, hepatosplenomegaly, cherry red spot on macula. | Niemann-Pick disease; Sphingomyelinase deficiency |
| Child with progressive neurodegeneration, developmental delay and cherry red spot on macula. | Tay-Sachs disease; Hexosaminidase A deficiency (Warren Tay was an ophthalmologist) |
| Cellular accumulation of: 1. GM2 ganglioside 2. sphingomyelin 3. Galactocerebroside 4. Glucocerebroside | 1. Tay-Sachs disease; Hexosaminidase A deficiency 2. Niemann-Pick disease; Sphingomyelinase deficiency 3. Krabbe's disease; Galactocerebrosidase deficiency 4. Gaucher's disease; glucocerebrosidase deficiency |
| Developmental delay, gargoylism, hepatosplenomegaly. | Hurler's syndrome; α-L-iduronidase deficiency |
| 1. Delivers dietary TG's to peripheral tissues and liver. Secreted by the intestines. 2. Delivers TG's to peripheral tissues. Secreted by the liver. | 1. chylomicrons 2. VLDL |
| Major apolipoproteins 1. binds LDL receptor 2. cofactor for lipoprotein lipase 3. mediates chylomicron secretion 4. mediates VLDL secretion 5. VLDL and chylomicron remnant reuptake by liver | 1. apoB-100 2. apoC-II 3. apoB-48 4. apoB-100 5. apoE |
| Cause of the following familial dyslipidemias: 1. ↑ LDL (cholesterol) 2. ↑ chylomicrons (triglycerides, cholesterol) 3. ↑ VLDL (triglycerides) | 1. familial hypercholesterolemia - absent LDL receptor 2. hyperchylomicronemia - lipoprotein lipase deficiency or altered apo C-II 3. hypertriglyceridemia - hepatic overproduction of VLDL |
| X-linked recessive lysosomal storage disease resulting in peripheral neuropathy, angiokeratomas cardiovascular/renal disease. | Fabry's disease |
| Galactocerebrosidase accumulations resulting in peripheral neuropathy, optic atrophy and developmental delays | Krabbe's disease |
| Where are the GLUT1, GLUT2, and GLUT4 glucose transporters located and which are insulin responsive? | 1. GLUT1: most tissues (RBC's, CNS) 2. GLUT2: β-slet, liver 3. GLUT4: adipocytes, skeletal muscle (insulin responsive) |
| Defect in ornithine transcaramoylase leads to mental retardation, seizures and ultimately death. What is the reason? | Hereditary hyperammonemia |
| What are the essential amino acids? | PVT. TIM HALL 1. phenylalanine 2. valine 3. threonine 4. tryptophan 5. isoleucine 6. methionine 7. histidine 8. arginine 9. leucine 10.lysine |
| What two features distinguish B12 deficiency from folate deficiency? | 1. neurological symptoms 2. elevated methylmalonic acid |
| 1. Where are fat soluble vitamins absorbed in the body? 2. Tapeworm leading to B12 deficiency | 1. ileum 2. Diphyllobothrium latum |
| 1. Which chemical reaction is THF used for? 2. If a defective urea cycle enzyme was the cause hyperammonemia, what would you expect the BUN to be? | 1. Used to donate a 1-carbon/methyl group 2. decreased |
| Which metabolic cycles occur in both the mitochondria and the cytoplasm? | HUGs take two 1. Heme synthesis 2. Urea cycle 3. Gluconeogenesis |
| Which enzymes have the following effect and are stimulated by insulin: 1. glycolysis 2. liver synthesis of fatty acids 3. glycogen synthesis | 1. glucokinase, PFK2, PDH 2. acetyl CoA carboxylase 3. glycogen synthase |
| Which enzymes of glycolysis require ATP? | 1. hexokinase/glucokinase 2. PFK-1 |
| Which enzymes of glycolysis produce ATP? | 1. Phosphoglycerate kinase 2. Pyruvate kinase 3. pyruvate dehydrogenase |
| Why does giving glucose alone to an alcoholic lead to lactic acidosis? | 1. to progress through glucolysis, pyruvate dehydrogenase requires thiamine (B1) 2. glycolysis ↑ to regenerate ATP but PDH deficiency causes shunting toward lactic acid |
| What are the 3 gluconeogenis substrates? | 1. alanine 2. lactate 3. glycerol 3-P |
| 1. Amino acids required during periods of growth 2. Amino acids found in histones | 1. arginine and histidine 2. arginine and lysine |
| What causes hyperammonemia vs hyperuricemia? | 1. hyperammonemia is caused by liver disease or defective urea cycle enzymes 2. huperuricemia is caused by ↑ purine turnover or gout |
| Albinism is a congenital deficiency of: (2 possibilities) | 1. tyrosinase 2. defective tyrosine transporters |
| What are the branched chain amino acids? | I Love Vermont maple syrupe 1. Isoleucine 2. Valine 3. Leucine |
| What are the two main ketone bodies? | 1. acetoacetate 2. β-hydroxybutyrate |
| Which two deficiencies can lead to fasting hypoglycemia and low ketones? | 1. Acyl-CoA dehydrogenase deficiency 2. Carnitine deficiency |
| What role does folate have in DNA synthesis? | N5N10 methylene THF is used with thymidylate synthase to create dTMP from dUMP |
| Which enzyme, found only in the liver, converts G6P to glucose for entrance into the bloodstream? | Glucose 6-phosphatase |
| Which vitamin is used to synthesize: 1. FAD 2. NAD | 1. B2 (riboflavin) 2. B3 (niacin) |
| In skeletal muscle, how is glycogen degraded to increase glucose supply for contracting muscle? | 1. calcium from the sarcoplasmic reticulum binds calmodulin and increases glycogen phosphorylase kinase 2. phosphorylase kinase activates glycogen phosphorylase leading to glycogenolysis |
| How long is the body reliant upon glycogen for energy between meals? | 24 hours |
| Which cells in the body are able to metabolize fructose and galactose? | hepatocytes |
| Which step of the TCA cycle undergoes substrate level phosphorylation? | succinyl-CoA is converted to succinate to produce GTP |
| 1. Which portion of collagen synthesis requires vitamin C? 2. Which portion of collagen synthesis requires copper? | 1. hydroxylation of proline and lysine residues 2. cross linking of collagen fibrils |
| 1. In riboflavin deficiency, with ETC component would be deficient? 2. Cause of propionic acidemia | 1. succinate dehydrogenase - B2 is used to synthesize FAD, an electron carrier of the TCA cycle 2. Deficiency of propionyl CoA carboxylase |
| Which organs metabolize: 1. fructose 2. galactose | 1. liver, kidney 2. liver, brain |
| 1. Which vitamin deficiency ↑ vulnerability to measles 2. allosteric activator of carbamoyl phosphate synthase I | 1. vitamin A 2. N-Acetylglutamate |
| Which neurotransmitters require tetrahydrobpterin as a cofactor | all catecholamines and serotonin |
| What enzymes can be defective in Ehler's danlos | 1. lysyl oxidase 2. pro-collagen peptidase |
| Which steps of collagen synthesis occur outside the fibroblast? | 1. cleavage of terminal regions of procollagen to form tropocollagen then cross-linking by lysyl oxidase to make collagen fibrils |
| Enzymatic deficiency leading to blackening of the skin and premature atherosclerosis | homocystinuria |
| What is NADPH from the hexose monophosphate shunt used for? | 1. producing reduced glutathione 2. cholesterol and fatty acid synthesis |
| What is the end product of sorbitol metabolism in the lens of healthy individuals | fructose |
| Where does the normal metabolism of fructose enter into glycolysis? | glyceraldehyde 3P |
| Growth retardation, seizures, musty body odor | phenylketonuria |
| Infant with vomiting, lethargy and burnt sugar smell in diaper | maple syrup urine disease - branched chain amino acid dehyrogenase deficiency (required thiamine B1) |
| Where does β-oxidation occur: 1. medium and short chain fatty acids 2. very long chain fatty acids | 1. mitochondria 2. peroxisome |
Created by:
amichael87
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