Metabolism US Medical PG Flashcards - Medical Study Cards
Master Metabolism with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Metabolism Flashcard Deck - 10 Cards
Flashcard 811: In what disease should the followings be restricted?
-Galactose
-Leucine
-Methionine
-Phenylalanine
-Tyrosine
Answer: Galactose: galactosemia (due to deficiency of Galactose-1-phosphate uridyl transferase) (GALT def.)
-Leucine: Maple syrup disease, due to deficiency of branched chain a-ketacid dehydrogenase.
-Methionine: should be restricted in homocysteinuria,because methionine converts to homocystein. Instead you will want to give B12 (cobalamine) to convert to methionine & B6 (pyridoxine) to convert to cysteine to relieve the high level of homocysteine.
-Phenylalanine: Phenylketonuria (def. of phenyl hydroxylase), musty odor, neurological symptoms.
-Tyrosine: restricted in hypertyrosinemia (progressive liver & renal disease) or in alkaptonuria (homogentisate oxidase def.) (black urine on air, black cartillage).
Flashcard 812: A deficiency of the following enzymes will lead to what disease?
-Delta- aminolevulinate dehydratase
-Delta-aminolevulinate synthase
-Cystathionine synthase
-Glucose-6-phosphate dehydrogenase
-Pyruvate kinase
Answer: D ALA dehydratase: Lead poisoning
-D ALA synthase: Sideroblastic anemia
-Cystathione synthase: usually convert homocystine to cystathionine (with help of B6), thus lead to homocystinuria.
-G6PD: hemolytic anemia
-Pyruvate kinase: (autosomal recessive disease) Hemolytic anemia.
Flashcard 813: In what disease the followings are associate with:
-Blood protoporphyrin level
-Erythocyte glucose-6-phosphate dehydrogenase activity
-Erythrocyte glutathione reductase activity
-Erythrocyte transketolase activity
-Serum methylmalonic acid level
-Serum NADPH
Answer: Blood protoporphyrin level: is the second to last enzyme in heme synthesis. It will be high in iron deficiency anemia and lead poisoning.
-G6PD activity: it could lead to hemolytic anemia, when level decreases.
-Erythrocyte gluthathione reductase activity: helps metabolize harmful oxygen species.
-Erythrocyte transketolase activity: will be decrease in thiamine deficiency (wernicke K. syndrome)
-Serum methylmalonic acid level: product of fatty acid oxydation. Converted to succinyl COA by methylmalonyl COA mutase. it will be increase in B12 deficiency.
-Serum NADPH: derived from Vit B3 (niacin)
Flashcard 814: What are the following in relation to carbs?
-Amylose
-Cellulose
-Galactose
-Lactose
-Maltose
-Sucrose
Answer: Amylose: are found in starch
-Cellulose: are found in cell of plants cells.
-Galactose, Lactose, Maltose: Lactose and maltose are found in breast milk. Lactose: breakdowns into glucose+galactose.
-Galactose: patient with galactosemia can't metabolize galactose.
-Sucrose: breakdown into glucose + fructose, fructose can't betabolize in fructokinase deficiency (some will due to exokinase "to the right reaction), can't metabolize at all in aldolase deficiency.
Flashcard 815: 61 y/o man found unresponsive on a sidewalk.
-He presents with breath smells of alcohol.
-He has gonal respirations and pulseless EKG, he's pronounced dead on arrival.
-Autopsy: necrosis are seen in mamillary bodies and gray matter surrounding 3rd & 4th ventricles.
-This patient's brain findings are most likely associated with a decrease in what?
Answer: Erythrocyte transketolase activity
Due wernicke korsakof syndrome due to thiamine deficiency (B1). It serves as a cofactor for 4 main enzymes:
-Pyruvate dehydrogenase
-Alpha ketogluterate dehydrogenase
-Branch alpha ketoacid dehydrogenase
-Transketolase
Flashcard 816: The followings conversion pathways are most likely deficent in what disease?
-Leucine to acetoacetate
-Phenylalanine to tyrosine
-Tyrosine to fumarate
Answer: Leucine to acetoacetate: Maple syrup urine disease, where leucine, valine, isoleucine will be elevated. (cerebral edema, seizures, sweet smell of urine)
-Phenylalanine to acetoacetate: PKU due to phenyl hydroxylase deficiency.
-Tyrosine to fumarate: Alkaptonuria due to lack of homogentisate dioxigenase enzymes. which cause high accumulation of homogentisate and lack of conversion of tyrosine to fumarate.
Flashcard 817: 23 y/o apparently healthy man who immigrated to the US comes to a clinic for regular check up.
-History: no significant mediacl problems but his mother told him he was bron with problem metabolizing sugar.
-Patient maintains no dietary restrictions and regularly eats vegetable, fruits meats.
-Urine samples: Repeatedly positive copper reduction test.
-Glucose oxidase dipstick test: negative
-Which enzyme is most likely to be deficient in this patient?
Answer: Fructokinase
due to Essential fructosuria which means it's not severe (benign condition)
Flashcard 818: A group of investigators is studying the regulation of catecholamines synthesis in response to severe stress.
-The experimental animals are found subsequently to have decreased production of epinephrine by the adrenal medulla compared with the control animals.
-Decreased activity of which enzymes is most likely responsible for the observed effect?
Answer: Phenylethanolamine-N-methyltransferase (PNMT)
wihch usually stimulated by cortisol
converted NE to Epi.
Flashcard 819: 1 day old boy is diagnosed with hyperphenylalanemia by newborn screening.
-He's placed on a special phenylalanine-restricted diet with tyrosine supplementation.
-Several months later, lab test results: normal serum phenylalanine level.
-Careful examination: some neurological abnormalities.
-Further workup: elevated prolactin.
-Physician suspects a cofactor deficiency.
-Which enzymes is most likely deficient in this patient?
Answer: Dihydrobiopterin reductase (BH2 reductase)
which leads to a deficiency of BH4, which leads to PKU and high prolactin due to lack of dopamin from the same pathway.
Flashcard 820: Exposures to what cellular pathway will cause these substances to increase?
-Ca2+
-cAMP
-cGMP
-Cl
-mRNA
-NO
Answer: Ca2+: will increase due to phospholipase C, protein kinase C pathway.
-cAMP, cGMP: will increase due to adenyl or guanylate cyclase, ATP, protein kinase A pathway. (sildenafil works in this pathway)
-Cl: tend to increase upon inhibition of neurotransmitters (GABA, glycine), will lead to hyperpolarization.
-mRNA: increase during cell division.
-NO: synthesize from arginine by NO synthase.
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