Biochemistry
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| 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
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| Deficiency results in: 1. Vitamin A 2. Vitamin B1 | 1. night blindness
2. thiamine deficiency: Beriberi and Wernicke-Korsakoff
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| Describe the two variants of beriberi? | 1. Dry beriberi: muscle wasting and neuropathy
2. Wet beriberi: neuropathy + cardiac failure (dilated cardiomyopathy)
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| 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)
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| 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
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| Two actions of vitamin B12 | 1. conversion of homocysteine to methionine
2. conversion of methylmalonyl-CoA to Succinyl-CoA
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| 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
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| 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
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| 1. Mechanism of Disulfuram 2. Mechanism of Fomepizole | 1. inhibits acetaldehyde dehydrogenase
2. inhibits alcohol dehydrogenase
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| 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
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| Malnutrition resulting in tissue and muscle wasting, loss of subcutaneous fat | Marasmus - Protein and carbohydrate malnutrition
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| Cell site of: 1. fatty acid oxidation 2. fatty acid synthesis 3. glycolysis 4. TCA cycle | 1. mitochondria
2. cytoplasm
3. cytoplasm
4. mitochondria
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| 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
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| First step in glycolysis | conversion of glucose to glucose 6 phosphate by hexokinase/glucokinase
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| Three causes of vitamin B3 deficieny | 1. Hartnup (↓ tryptophan absorption)
2. malignant carcinoid syndrome (↑ tryptophan metabolism)
3. isoniazide (↓ vitamin B6)
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| Peripheral neuropathy and dermatitis from isoniazide usage is due to: | B6 deficiency
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| 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
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| 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
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| 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
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| 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)
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| 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
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| 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
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| 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
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| 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
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| Which enzymes does Vitamin B1 (thiamine) serve as cofactor for? | 1. pyruvate dehydrogenase
2. α-ketoglutarate dehydrogenase
3. transketolase
4. branched-chain AA dehydrogenase
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| 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)
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| 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
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| 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
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| What is the Cori cyce? | 1. glucose → pyruvate → lactate in skeletal muscle and RBCs
2. Lactate converted back to glucose in hepatocytes
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| Enzyme deficiency when Fructose-1-phosphate accumulates in hepatocytes | Fructose intolerance; aldolase B deficiency
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| Benign syndrome in which a defective enzyme results in fructose in the blood and urine. | Essential fructosuria; fructokinase deficiency
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| 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
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| Accumulation of galactose substances results in development of cataracts, hepatosplenomegaly and mental retardation. | Galactosemia; absence of galactose-1-phosphate uridyltransferase
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| Mild condition of galactose metabolism resulting in infantile cataracts. | Galactokinase deficiency
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| 1. Enzyme responsible for sorbitol accumulation in tissues? 2. Which tissues are most effected? | 1. aldose reductase
2. schwann cells, lens, retina and kidneys
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| 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
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| 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
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| 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
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| 2 causes of homocysteinuria | 1. cystathionine synthase
2. hemocysteine methyltransferase deficiency
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| 1. Blocked degradation of branched amino acids 2. What enzyme is deficient? | 1. maple syrupe urine disease
2. α-ketoacid dehydrogenase
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| 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
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| 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
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| Severe fasting hypoglycemia, elevated liver glycogen, hepatomegaly. | Von Gierke's disease; Glucose-6-phosphatase deficiency
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| Glycogen storage disease resulting in cardiomegaly and systemic findings leading to early death | Pompe's disease; lysosomal α-1,4-glucosidase deficiency (acid maltase)
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| Glycogen storage disorder with painful muscle cramps and myoglobinuria with strenuous exercise. | McArdle's disease; skeletal muscle glycogen phosphorylase deficiency
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| Hepatosplenomegaly, glucocerebroside accumulations. | Gaucher's disease; β-glucocerebrosidase
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| Child with progressive neurodegeneration, hepatosplenomegaly, cherry red spot on macula. | Niemann-Pick disease; Sphingomyelinase deficiency
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| Child with progressive neurodegeneration, developmental delay and cherry red spot on macula. | Tay-Sachs disease; Hexosaminidase A deficiency
(Warren Tay was an ophthalmologist)
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| 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
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| Developmental delay, gargoylism, hepatosplenomegaly. | Hurler's syndrome; α-L-iduronidase deficiency
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| 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
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| 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
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| 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
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| X-linked recessive lysosomal storage disease resulting in peripheral neuropathy, angiokeratomas cardiovascular/renal disease. | Fabry's disease
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| Galactocerebrosidase accumulations resulting in peripheral neuropathy, optic atrophy and developmental delays | Krabbe's disease
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| 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)
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| Defect in ornithine transcaramoylase leads to mental retardation, seizures and ultimately death. What is the reason? | Hereditary hyperammonemia
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| 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
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| What two features distinguish B12 deficiency from folate deficiency? | 1. neurological symptoms
2. elevated methylmalonic acid
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| 1. Where are fat soluble vitamins absorbed in the body? 2. Tapeworm leading to B12 deficiency | 1. ileum
2. Diphyllobothrium latum
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| 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
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| Which metabolic cycles occur in both the mitochondria and the cytoplasm? | HUGs take two
1. Heme synthesis
2. Urea cycle
3. Gluconeogenesis
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| 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
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| Which enzymes of glycolysis require ATP? | 1. hexokinase/glucokinase
2. PFK-1
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| Which enzymes of glycolysis produce ATP? | 1. Phosphoglycerate kinase
2. Pyruvate kinase
3. pyruvate dehydrogenase
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| 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
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| What are the 3 gluconeogenis substrates? | 1. alanine
2. lactate
3. glycerol 3-P
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| 1. Amino acids required during periods of growth 2. Amino acids found in histones | 1. arginine and histidine
2. arginine and lysine
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| 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
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| Albinism is a congenital deficiency of: (2 possibilities) | 1. tyrosinase
2. defective tyrosine transporters
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| What are the branched chain amino acids? | I Love Vermont maple syrupe
1. Isoleucine
2. Valine
3. Leucine
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| What are the two main ketone bodies? | 1. acetoacetate
2. β-hydroxybutyrate
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| Which two deficiencies can lead to fasting hypoglycemia and low ketones? | 1. Acyl-CoA dehydrogenase deficiency
2. Carnitine deficiency
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| What role does folate have in DNA synthesis? | N5N10 methylene THF is used with thymidylate synthase to create dTMP from dUMP
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| Which enzyme, found only in the liver, converts G6P to glucose for entrance into the bloodstream? | Glucose 6-phosphatase
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| Which vitamin is used to synthesize: 1. FAD 2. NAD | 1. B2 (riboflavin)
2. B3 (niacin)
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| 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
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| How long is the body reliant upon glycogen for energy between meals? | 24 hours
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| Which cells in the body are able to metabolize fructose and galactose? | hepatocytes
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| Which step of the TCA cycle undergoes substrate level phosphorylation? | succinyl-CoA is converted to succinate to produce GTP
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| 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
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| 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
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| Which organs metabolize: 1. fructose 2. galactose | 1. liver, kidney
2. liver, brain
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| 1. Which vitamin deficiency ↑ vulnerability to measles 2. allosteric activator of carbamoyl phosphate synthase I | 1. vitamin A
2. N-Acetylglutamate
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| Which neurotransmitters require tetrahydrobpterin as a cofactor | all catecholamines and serotonin
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| What enzymes can be defective in Ehler's danlos | 1. lysyl oxidase
2. pro-collagen peptidase
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| 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
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| Enzymatic deficiency leading to blackening of the skin and premature atherosclerosis | homocystinuria
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| What is NADPH from the hexose monophosphate shunt used for? | 1. producing reduced glutathione
2. cholesterol and fatty acid synthesis
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| What is the end product of sorbitol metabolism in the lens of healthy individuals | fructose
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| Where does the normal metabolism of fructose enter into glycolysis? | glyceraldehyde 3P
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| Growth retardation, seizures, musty body odor | phenylketonuria
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| Infant with vomiting, lethargy and burnt sugar smell in diaper | maple syrup urine disease - branched chain amino acid dehyrogenase deficiency (required thiamine B1)
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| Where does β-oxidation occur: 1. medium and short chain fatty acids 2. very long chain fatty acids | 1. mitochondria
2. peroxisome
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