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Biochemistry 1
First Aid Biochemistry 1
| Question | Answer |
|---|---|
| Fat soluble vitamins | A, D, E, and K |
| Only water soluble vitamin stored in the body | B12; stored in the liver |
| Vitamin A deficiency results in? | Night blindness |
| Vitamin B1 deficiency results in? | thiamine deficiency, Beriberi and Wernicke-Korsakoff syndrome |
| Describe the two variants of beriberi? | Dry beriberi marked by muscle wasting and polyneuritis; Wet beriberi marked by cardiac failure (dilated cardiomyopathy) |
| What is Wernicke-Korsakoff syndrome? | Thiamine deficiency often as a result of alcoholic malnutrition; marked by vision changes, ataxia, and impaired memory |
| Vitamin B2 deficiency results in? | Riboflavin; Angular stomatitis |
| Vitamin B3 deficiency results in? | Niacin; Pellagra (3D's: dementia, diarrhea, dermatitis) |
| Vitamin B12 deficiency results in? | Megaloblastic anemia with neurologic changes |
| What are the two actions of B12? | Conversion of homocysteine to methionine and conversion of methylmalonyl-CoA to Succinyl-CoA; deficiency results in methylmalonic acid accumulation (Homocysteine will accumulate if B6 is deficient as well) |
| Folic acid deficiency results in? | Megaloblastic anemia w/out neurologic changes |
| Biotin deficiency is commonly caused by? | Avidin in egg whites; consumption of raw eggs |
| Vitamin C deficiency results in? | Scurvy; swollen gums, bruising, anemia, poor wound healing |
| Vitamin D deficiency results in? | Ricketts in kids; osteomalacia in adults |
| Vitamin E deficiency results in? | Hemolysis (antioxidant that protects erythrocytes) and neurodysfunction |
| Vitamin K deficiency results in? | Bleeding disorders; increased PT and PTT with normal bleeding time (normal platelets) |
| Why does ethanol cause hypoglycemia? | Consumption of NAD by alcohol dehydrogenase results in shunting of pyruvate and OAA to lactate and malate respectively, inhibiting gluconeogenesis |
| What is the mechanism of action of Disulfuram and what is it used for? | Inhibits acetaldehyde dehydrogenase leading to acetaldehyde accumulation, used in the treatment of chronic alcoholics |
| Protein malnutrition resulting in skin lesions, edema, and liver malfunction (fatty change) | Kwashkior |
| Energy malnutrition resulting in tissue and muscle wasting, loss of fat, and variable edema | Marasmus |
| Mutation in DNA repair resulting in predisposition for melanoma and other cancers. | Nucleotide excision repair; mutated in xeroderma pigmentosa |
| Mutation in DNA repair resulting in hereditary nonpolyposis colon cancer? | Mismatch repair |
| Direction of DNA and RNA synthesis | 5' to 3' |
| mRNA initiation and stop codons? | Start: AUG; Stop: UGA, UAA, UAG |
| What are the 3 steps of RNA processing? | 1. Capping 5' end w/ 7-methyl-G; 2. Polyadenylation of 3' end; 3. splicing out of introns |
| I-cell disease is a result of what dysfunction? | Failure of addition of mannose-6-phosphate to lysosome proteins, enzymes secreted outside of cell instead of targeted for destruction. |
| What are the symptoms of I-cell disease | Coarse facial features, clouded corneas, and restricted joint movements |
| Syndrome of immotile cilia resulting in infertility, bronchiectasis, and recurrent sinusitis? | Kartagener's syndrome |
| Symptoms of this disorder include skeletal abnormalities (arachnodactyly), astigmatism, and various cardiovascular problems. | Marfan's syndrome |
| Symptoms of this disorder include hyperextensible skin, easy bruising, and hypermobile joints. | Ehler-Danlos syndrome |
| Symptoms of this disorder include multiple fractures, blue sclera, hearing loss, and dental imperfections. | Osteogenesis imperfecta (hearing loss is due to abnormal middle ear bones); may be confused with child abuse |
| Site of fatty acid oxidation and Krebs cycle | mitochondria |
| Site of glycolysis, fatty acid synth, and HMP shunt | cytoplasm |
| Differences between hexokinase and glucokinase? | Hexokinase has feedback inhibition by G6P, is high affinity, low capacity, and ubiquitously expressed. Glucokinase has no inhibition, low affinity, high capacity, and only found in the liver. |
| What is the first step in glycolysis and what inhibits this step? | conversion of glucose to glucose 6 phosphate by hexokinase/glucokinase; inhibited by glucose 6 phosphate if hexokinase |
| What is the rate limiting step in glycolysis and what inhibits and activates this step? | Conversion of F-6-phosphate to F-1,6-bisphosphate by PFK1; it is inhibited by ATP and citrate, activated by F-2,6-BP (most potent) |
| What inhibits conversion of pyruvate to acetyl-CoA? | Inhibited by ATP, NADH, and acetyl-CoA |
| Describe the enzyme that regulates F-2,6-BP? | Bifunctional enzyme, FBPase 2 which is active in the fasting state and serves to generate F-2,6-BP to increase glycolysis, and PFK-2 which is active in the fed state and serves to decrease F-2,6-BP |
| Why does pyruvate kinase deficiency result in hemolytic anemia? | Because RBC's have no mitochondria and depend solely on glycolysis for energy |
| What are the 5 cofactors necessary for pyruvate dehydrogenase? | TPP (B1;thiamine), FAD (B2; riboflavin), NAD (B3; niacin), CoA (B5; pantothenate), and lipoic acid; These are also necessary for alpha-ketoglutarate DH |
| Arsenic inhibits what enzymes? | pyruvate DH and alpha-ketoglutarate DH; arsenic inhibits lipoic acid, symptoms of poisening include vomiting, rice water stools, and garlic breath |
| Necessary cofactor for gluconeogenesis conversion of pyruvate to oxaloacetate? | Biotin, ATP |
| What is the Cori cycle? | Conversion of glucose to pyruvate to lactate in skeletal muscle and RBC's by lactate dehydrogenase, and conversion of lactate back to glucose in hepatocytes also by lactate DH. |
| In the Cori cycle why is there a net negative of 4 ATP? | Yields 2 ATP to convert glucose to lactate but requires 6 ATP to convert lactate back to glucose. |
| NADPH is required for what processes? | Fatty acid and steroid synthesis, glutathione reduction in RBC's, and cytochrome-P450 |
| In this syndrome, a decrease in available phosphate results in inhibition of both glycogenolysis and gluconeogenesis. | Fructose intolerance; aldolase B deficiency |
| In this benign syndrome, a defective enzyme results in fructose in the blood and urine. | Essential fructosuria |
| Accumulation of toxic galactose substances results in the development of cataracts, hepatosplenomegaly, and mental retardation. | Galactosemia; absence of galactose-1-phosphate uridyltransferase |
| Loss of this brush border enzyme leads to the development of bloating, cramps, and osmotic diarrhea. | Lactase deficiency |
| What is the cause of phenylketonuria? | Decreased phenylalanine hydroxylase or THB cofactor necessary for tyrosine synthesis leads to phenylalanine buildup and deficient tyrosine |
| What is the deficient enzyme in alkaptonuria? | Deficiency of homogenistic acid oxidase necessary to degrade tyrosine |
| What are the 3 causes of homocysteinuria? | cystathionine synthase deficiency, decreased affinity of cystathionine synthase for B6, and methionine synthase deficiency |
| This inherited defect of renal tubular amino acid transporters results in kidney stones. | Cystinuria |
| Deficient alpha-ketoacid DH results in blocked degradation of branched amino acids in this disease. | Maple syrup urine disease |
Created by:
rahjohnson
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