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119 Cards in this Set
- Front
- Back
To what main two molecules is iron bound in human cells? To what main two molecules is iron bound in blood?
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Myoglobin and ferritin; Hemoglobin and transferrin.
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What are some of the clinical effects of zinc deficiency?
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Delayed wound healing, acrodermatitis enteropathica, anorexia, diarrhea, growth retardation, depressed mental function, impaired night vision, and infertility.
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What are some of the signs of hypocalcemia?
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Tetany and neuromuscular instability, Chvostek's sign, Trousseau's sign.
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You see basophillic stippling on a peripheral blood smear. What's your diagnosis?
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Lead poisoning.
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What two enzymes are inhibited by lead poisoning?
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Ferrochelatase and ALA dehydratase.
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What might you see in an erythrocyte of a patient with lead poisoning?
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Basophillic stippling.
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What would be some of the clinical signs in a patient that would lead you to suspect lead poisoning?
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Anemia, colicky abd pain, diarrhea, nausea, encephalopathy, WRIST DROP, FOOT DROP, lead lines on gingivae
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What are the features of Plummer-Vinson syndrome?
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Dysphagia, glossitis, Iron-deficiency.
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What is the rate limiting step in the HMP shunt (PPP)? What is produced in this pathway? Which tissues utilize this pathway?
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G6PD; NADPH and Ribulose-5-P (for nucleotide synthesis); RBCs, liver, adrenal cortex, lactating mammary glands.
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A deficiency in G6PD leads to what? What is the inheritance pattern of this deficiency?
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Hemolytic anemia (no G6PD = no NADPH = no glutathione reductase activity = bunches of oxidized glutathione running around in the cell lysing stuff --> this is bad); X-linked.
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The respiratory burst (oxidative burst) is dependent on what enzyme?
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NADPH oxidase.
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What are the histological characteristics of G6PD deficiency?
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Heinz bodies and bite cells.
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What is the defective enzyme in essential fructosuria? What are the symptoms?
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FRUCTOKINASE -- i.e., fructose can't get into the cell; Asymptomatic -- fructose appears in blood and urine.
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What is the defective enzyme in Fructose Intolerance? What substrate accumulates? What are the symptoms?
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ALDOLASE B; Fructose-1-P accumulates in cell, bogarting all the phosphate! None for gluconeogenesis or glycogenolysis; Sx include hypoglycemia, jaundice, cirrhosis, vomiting.
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What are the symptoms of Galactokinase Deficiency?
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Accumulation of galactitol in the lens of eye --> can lead to infantile cataracts. Relatively benign condition.
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What is the deficient enzyme in Classic Galactosemia? How does it present?
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Galactose-1-phosphate uridyltransferase --> accumulation of toxic substances like galactitol; Failure to thrive, jaundice, hepatomegaly, infantile cataracts, mental retardation, ascites.
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What enzyme converts glucose to sorbitol?
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Aldose reductase.
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What is the primary energy source in a patient that has not eaten in two days? What is the brain using for energy in this situation?
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Fatty acids. Glucose and some ketone bodies.
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What is the rate-limiting enzyme in ketone body synthesis?
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HMG-CoA synthase.
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Which ketone body is metabolized by muscle and brain tissue?
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β-hydroxybutarate.
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When does gluconeogenesis begin in the post-absorptive period? When does it become fully active?
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Begins 4-6 hours after the last meal; in full swing at 10-18 hours after last meal.
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What determines survival time after 3 days of starvation?
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Amount of adipose stores.
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This drug inhibits acetaldehyde dehydrogenase.
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Disulfuram -- acetaldehyde accumulates, contributing to hangover symptoms.
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This drug inhibits alcohol dehydrogenase and is an antidote for methanol or ethylene glycol poisoning.
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Fomepizole.
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How does chronic alcoholism cause hypoglycemia?
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The body needs NAD+ to metabolize alcohol, AND to do gluconeogenesis. The NAD+ gets depleted doing EtOH metabolism, increasing the NADPH:NAD+ and shutting down gluconeogenesis.
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What are some of the hallmarks of Kwashikor? How about Marasmus?
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Kwashikor: protein malnutrition, protruding belly, edema, skin lesions, sick liver, anemia.
Marasmus: generalized malnutrition, tissue and muscle wasting, loss of sc fat and variable edema. |
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What deficiency causes familial hypercholesterolemia?
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Absent or decreased synthesis of LDL receptors.
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Which apolipoprotein is responsible for mediating the secretion of chylomicrons from the enterocytes of the gut?
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Apo B-48
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Which apolipoprotein binds to the LDL receptor and is also responsible for the secretion of VLDL from the liver?
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Apo B-100
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Which apolipoprotein acts as a cofactor for LPL?
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Apo C-II
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Which apolipoprotein mediates the uptake of chylomicron remnants?
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Apo E
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Which apolipoprotein activates LCAT?
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Apo A-1
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Where does FA synthesis take place? FA degradation? What are the rate-limiting enzymes for these reactions?
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Cytosol; Mitochondria; Acetyl Co-A carboxylase and Carnitine acyl transferase (CAT).
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Name 3 of the Omega-3 Fatty Acids.
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EPA, DHA, and α-Linoleic Acid.
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What are the essential amino acids?
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"PVT TIM HALL": Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histadine, Arginine, Leucine, and Lysine.
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What are the ketogenic amino acids?
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Leucine, Lysine.
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What are the glucogenic amino acids?
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Methionine, valine, arginine, histadine.
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What are the acidic amino acids?
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Aspartate and glutamate.
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What are the basic amino acids? Where do we find these guys?
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Arginine, Lysine, and histadine. You'll find these guys in the histones of DNA (b/c they are negatively charged)!
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What AA is the precursor to histamine?
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Histadine.
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What AA is the precursor to porphyrin and heme?
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Glycine.
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What AA is the precursor to NO?
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Arginine.
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What AA is the precursor to GABA?
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Glutamate.
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What AA is the precursor to SAM?
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Methionine.
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What is the AA precursor of creatine?
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Arginine.
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What is the path of catecholamine synthesis?
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Phenylalanine --> tyrosine --> dopa -> dopamine --> NE --> Epi
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A deficiency in tyrosine hydroxylase will lead to a build-up of what substrate?
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Tyrosine; can go to thyroxine.
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A deficiency in phenylalanine hydroxylase will lead to a build-up of what substrate?
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Phenylalanine.
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A deficiency in dopa carboxylase will lead to a build-up of what substrate?
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Dopa; can go to melanin.
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What are the catecholamine breakdown products via MAO and COMT?
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Dopamine --> HVA
NE --> VMA Epi --> Metanephrine |
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What is the rate limiting enzyme in the urea cycle? Where does this enzyme live?
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Carbamoyl phosphate synthetase I; it lives in the mitochondria.
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What is the most common urea cycle disorder? How does this present? What is the inheritance pattern?
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Ornithine transcarboamoylase (OTC) deficiency; Orotic acid in blood and urine (crystals in diaper), decreased BUN, sx of hyperammonemia; X-linked recessive.
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What are the symptoms of ammonia intoxication (hyperammonemia)?
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Tremor, slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision.
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Explain the mechanism of action of lactulose in removing NH4+ from the blood.
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Lactulose --> acidifies the gut --> traps NH4+ --> excretion.
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A full-term neonate becomes mentally retarded and hyperactive and has a must body odor. Phenylketones are detected in the urine. What is the diagnosis? What is the deficient enzyme?
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PKU. Deficient phenylalanine hydroxylase or tetrahydrobiopterin cofactor.
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What dietary modifications should a patient with PKU make?
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Decrease phenylalanine, increased tyrosine, increased THB.
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A middle-aged man has dark spots on his sclera and has noted that his urine turns black when left sitting for a period of time. What is the dx? What is the deficient enzyme?
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Alkaptonuria; Deficiency in homogentisic acid oxidase.
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Albinism is caused by a deficiency in one of these two things..
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Tyrosinase (which synthesizes melanin from tyrosine) or defective tyrosine transporters. Also can be d/t lack of migration of NEURAL CREST CELLS! remember, they give rise to melanocytes!
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What are the findings in a patient with homocystinuria?
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Elevated homocystine in urine, mental retardation, osteoporosis, tall stature, kyphosis, LENS SUBLUXATION and ATHERSCLEROSIS.
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What does S-adenosyl-methionine (SAM) do and what is required to regenerate SAM?
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Methyl donor -- required for the synthesis of epi from NE; Requires Vitamin B12 and folate in order to be regenerated.
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What causes Maple syrup urine disease?
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Blocked degradation of BRANCHED chain amino acids (isoleucine, leucine, and valine) due to deficient α-KETOACID DEHYDROGENASE.
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What symptoms does Hartnup disease present with?
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Tryptophan excretion in urine and decreased absorption from gut -- PELLAGRA.
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What accounts for the positive charge on histones? What accounts for the negative charge on DNA?
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Lysine and arginine residues; Phosphate groups.
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Which amino acids are required for de novo purine synthesis? What else is required?
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Glycine, aspartate, glutamine. THF.
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What is the rate-limiting enzyme in pyrimidine synthesis?
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CPSII. It happens in the cytosol, FYI.
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What is the biochemical result of Lesch-Nyhan syndrome?
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No HGPRT = no de novo synthesis of purines. Excess uric acid production and de novo purine synthesis. X-linked recessive.
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What is the main treatment for Lesch-Nyhan syndrome?
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Need to prevent excessive amounts of uric acid -- use a xanthine oxidase inhibitor like ALLOPURINOL.
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This drug blocks DHFR.
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Methotrexate (humans), TMP (bacteria).
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This drug block thymidylate synthase.
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5-FU.
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This drug blocks ribonucleotide reductase.
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Hydroxyurea.
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This drug blocks de novo purine synthesis.
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6-MP.
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What's the problem in orotic aciduria? What are the signs and sx?
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No conversion of orotic acid to UMP (de novo pyrimidine synth) d/t defect in orotic acid phosphoribyltransferase or orotidine 5-phosphate decarboxylase; increased orotic acid in urine (crystals in diaper), megaloblastic anemia refractive to B12 or folate tx, failure to thrive, no hyperammonemia.
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What is the defect in Xeroderma pigmentosum?
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Mutated nucleotide excision repair --> no repair of thymidine dimers caused by UV exposure.
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Which DNA repair mechanism is mutated in BRCA1 and BRCA2 mutations, and in patients with ataxia-telangiectasia?
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Nonhomologous end joining.
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What is the genetic defect responsible for HNPCC?
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Mismatch repair.
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What are the differences between carbamoyl phosphate synthetase I and II with regard to location, pathway, and nitrogen source?
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CPSI: Located in the mitochondria, urea cycle, and ammonia is its nitrogen source.
CPSII: Located in the cytosol, pyrimidine synthesis, glutamate is its nitrogen source. |
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What are some of the sx of zinc deficiency?
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Delayed wound healing, decreased immune response, mental retardation, impaired vision, infertility, alopecia, dysgeusia, anosmia, ACRODERMATITIS ENTEROPATHICA (lesions around mouth and anus + diarrhea).
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To which molecules is iron bound in human cells? What about in the blood?
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Myoglobin and Ferritin; Transferrin and Hb.
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What are some of the signs of hypocalcemia?
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Trousseau's sign and facial spasm.
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What organs are primarily affected by cadmium excess?
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Bones, lung, kidney.
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What organs are primarily affected by an excess of mercury?
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Kidneys, brain.
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Which antibiotic inhibits prokaryotic RNA polymerase? Topoisomerase? DHFR?
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Rifampin; Fluoroquinolones; TMP.
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Which antibiotic inhibits 50S peptidyltransferase? Which binds 50S and blocks translocation? Which binds 30S and prevents attachment of tRNA?
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Streptogramins; Macrolides; Tetracyclines.
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How does Vit D exert its effects?
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Interacts directly with DNA to selectively stimulate or repress gene expression.
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What is another name for D2 and where does it come from? What is another name for D3 and where does it come from? How does Vit D deficiency manifest in children? adults?
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Ergocalciferol - plants.
Cholecalciferol - consumed in diet, synth in sun-exposed skin. Rickets in children. Osteomalacia in adults. |
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How does Vit D def bring about Rickets and Osteomalacia?
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Decreased bone mineral deposition. If def occurs at the growth plate, growth slows and bone age is retarded (Rickets). Poor mineralisation of trabecular bone, resulting in a greater proportion of unmineralised osteoid, is the condition of osteomalacia. Rickets is found only in growing children before fusion of the epiphyses, whereas osteomalacia is present at all ages.
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What enzyme is responsible for the activation of Vit D? Where does this process occur?
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α1-hydroxylase converts 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol in the KIDNEY.
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In what disease does Vit D toxicity result from excess MACROPHAGE generation of 25-hydroxycholecalciferol?
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Sarcoidosis.
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What pharmacological agents can cause Vit K deficiency with long-term use?
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Warfarin, antibiotics (loss of gut bacteria), anticonvulsants.
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What are the different forms of Vitamin A?
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Retinol, retinal, B-carotene, retinoic acid.
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What disease can be treated with Vitamin A?
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AML-M3, measles.
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What is the function of Vitamin A?
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Antioxidant, constituent of visual pigment, need it for normal differentiation of epithelial cells.
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What are the signs of Vitamin A deficiency?
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Lots of EYE PATHOLOGY: Night blindness, xeropthalmia, corneal ulceration, keratmalacia (clouding of cornea), Bitot's spots (silver plaques on the conjunctiva).
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What are the signs of hypervitaminosis A?
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Headache, N & V, stupor, dry + pruritic skin, hepatomegaly, bone and joint pain, alopecia, increased ICP; TERATOGEN in pregnant women (NC defects -- cleft palate, cardiac abnormalities, etc.).
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What headache condition can most commonly result from an excess of Vitamin A?
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Pseudotumor cerebri.
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What is the main metabolic reaction that Vitamin C is involved in?
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Hydroxylation of proline and lysine residues in the synthesis of collagen.
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What are the major signs of Vit C deficiency?
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Sore, spongy gums, loose teeth, fragile blood vessels --> hemorrhages, swollen joints (bleeding into joint spaces), impaired wound healing, anemia.
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What is the primary function of Vitamin E?
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Antioxidant -- protects RBCs from non-enzymatic oxidation of cell components.
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What is associated with Vitamin E deficiency? What autosomal recessive gene mutation is responsible for Vitamin E deficiency?
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Spinocerebellar degeneration leading to ATAXIA, peripheral neuropathy, proximal muscle weakness, increased fragility of RBCs, ACCELERATED ATHEROSCLEROSIS; α-tocopherol transfer gene protein.
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What is the biologically active form of folic acid? What metabolic reactions is it involved in? What does a deficiency in folic acid cause?
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THF; synthesis of purines (A, G) and thymine (T); megaloblastic anemia, growth defects, neural tube defects.
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What results from an excess of folate? Why?
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Vitamin B12 deficiency, it's used in making THF -- get this, A deficiency in B12 can cause a deficiency in folate.
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In what metabolic reactions in Vitamin B12 involved?
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Homocysteine and THF-CH3 --> Methionine and THF.
Methylmalonyl CoA --> Succinyl CoA. |
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What is seen in B12 deficiency?
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Pernicious anemia; megaloblastic anemia, CNS sx, atrophy of stomach glands, homocysteinuria and methylmalonic acid in urine.
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What is another name of B12 deficiency?
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Subacute combined degeneration.
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What is usually the cause of B12 malabsorption? Where is B12 absorbed in the GI tract? Name two malabsorption problems that can cause B12 deficiency.
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AI destruction of parietal cells = no IF = no B12 absorption; terminal ileum; Crohn's disease and celiac sprue.
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What is the tx for B12 deficiency?
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IM injection of cyanocobalamin.
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What is the biologically active form of Vitamin B6? What is its metabolic function?
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Pyridoxal phosphate; coenzyme for many enzymes, esp those involved in AA metabolism (transamination).
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What drugs can cause a B6 deficiency? What are the clinical findings of a B6 deficiency?
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Isoniazid, OCPs; Convulsions, hyperirritability, and peripheral neuropathy.
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What is Vitamin B1? What reactions is Vitamin B1 involved in?
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Thiamine; pyruvate --> acetyl CoA (via PDH); α-Ketoglutarate --> succinyl CoA for TCA cycle (via α-Ketoglutarate dehydrogenase; Ribose 5-P --> G3P in HMP shunt (via transketolase).
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What two syndromes are associated with B1 deficiency? In which populations do these occur?
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Beriberi (dry and wet) -- populations where rice is the major component of the diet; Wernicke-Korsakoff syndrome -- alcoholics.
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What are the characteristics of dry beriberi? Wet beriberi?
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Peripheral neuropathy, toe-drop, wrist-drop, and foot-drop, muscle weakness, hyporeflexia and areflexia; Wet beriber includes peripheral vasodilation --> high-output heart failure --> peripheral edema, cardiomegaly.
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Describe Wernike-Korsakoff syndrome. What is the classic triad? What are other sx?
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Classic Triad : Confusion, opthalmoplegia, ataxia; other sx include confabulation, personality change, memory loss (permanent).
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What are the two biologically active forms of B2 (riboflavin)? What is their function?
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FMN and FAD, cofactors in oxidation and reduction reactions.
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What are some of the symptoms of B2 deficiency? In what populations is this prevalent?
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Dermatitis, cheilosis/angular stomatitis (fissuring and inflammation at the corners of the mouth), glossitis, corneal vascularization; denture wearers.
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What are the biologically active forms of niacin (Vitamin B3)? What is their function?
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NAD+, NADP+; cofactors for oxidation-reduction reactions.
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From which amino acid is niacin derived?
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Tryptophan.
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What disease is caused by niacin deficiency? What are the sx? What can cause niacin deficiency?
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Pellagra; diarrhea, dementia, dermatitis; Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), INH (decreased Vit B6).
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What is the function of Vit B5 (pantothenate)? What sx occur with deficiency?
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It's a component of coenzyme A and fatty acid synthase; "DEA": dermatitis, enteritis, alopecia, adrenal insufficiency.
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What is the metabolic role of biotin? What can cause a deficiency in biotin?
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Apoenzyme in carboxylation reactions; excessive consumption of egg whites, abx use. (gut bacteria make biotin for us).
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