Clinical Qbank(1st Year Subjects)

289. Explanation A) • Melanin is pigment of skin, hair and eyes, synthesized from tyrosine in the epidermis by the melanocytes. • Function: Protect underlying cells from UV rays of sun. • Defect in melanin production: Albinism • Generalized Albinism aka Oculocutaneous albinism (OCA) is mainly classified into 3 types: ƒ OCA 1: Tyrosinase deficient ƒ OCA 2: Tyrosinase positive- MC type of albinism ƒ OCA 3: Red OCA • Localized albinism: Piebaldism, Waardenburg syndrome Practice first proff questions at @firstyearmbbsquestions

288. Explanation A) Phenylketonuria • MC metabolic disorder of amino acid • Seen due to deficiency of enzyme: Phenylalanine Hydroxylase • Increased phenylalanine in blood → metabolized to phenylketones → excreted in urine → hence the name Phenylketonuria (PKU). • MC organ damaged due to phenylalaninemia: Brain Clinical Feature • Gradual development of mental retardation (intellectual disability) ƒ Infants normal at birth • Excessive vomiting • Autistic, choreiform movement • Unpleasant, musty odor Diagnosis • Guthrie test-screening test in blood sample • Ferric chloride test: Screening test in urine sample • Tandem mass spectrometry: IOC Practice first proff questions at @firstyearmbbsquestions

287. Explanation A) • Lysyl oxidase is an extracellular copper enzyme that catalyzes formation of aldehydes from lysine residues in collagen and elastin precursors. Practice first proff questions at @firstyearmbbsquestions

286. Explanation A) • Those enzymes that require inorganic metal ions as their cofactor are termed as metalloenzymes aka cofactors. • Dopamine hydroxylase is a copper-containing enzyme involved in the synthesis of the catecholamines: Norepinephrine and Epinephrine from tyrosine in the adrenal medulla and central nervous system. • Ascorbic acid is also linked with copper containing hydroxylases such as peptidoglycine hydroxylase and dopamine hydroxylase. Dopamine decarboxylase requires pyridoxal phosphate for the conversion of L-dopa 3,4-dihydroxyphenylethylamine Practice first proff questions at @firstyearmbbsquestions

285. Explanation A) • Collagen is the most abundant protein in the body. • Harrisons states: “The first genes cloned for connective tissues were the two genes coding for type I collagen, the most abundant protein in bones, skin, tendons, and several other tissues. Practice first proff questions at @firstyearmbbsquestions