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Biochemistry 1

First Aid Biochemistry 1

QuestionAnswer
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