Description : Albinism is due to deficiency of the enzyme: (A) Phenylalanine hydroxylase (B) Tyrosinase (C) p-Hydroxyphenylpyruvic acid oxidase (D) Tyrosine dehydrogenase
Last Answer : Answer : C
Description : Selenium is a constituent of the enzyme: (A) Glutathione peroxidase (B) Homogentisate oxidase (C) Tyrosine hydroxylase (D) Phenylalanin hydroxylase
Last Answer : Answer : A
Description : DOPA is an intermediate in the synthesis of (A) Thyroid hormones (B) Catecholamines (C) Melanin (D) Catecholamines and melanin
Last Answer : Answer : D
Description : The enzyme using some other substance, not oxygen as hydrogen acceptor is (A) Tyrosinase (B) Succinate dehydrogenase (C) Uricase (D) Cytochrome oxidase
Last Answer : Answer : B
Description : Richner-Hanhart syndrome is due to defect in (A) Tyrosinase (B) Phenylalanine hydroxylase (C) Hepatic tyrosine transaminase (D) Fumarylacetoacetate hydrolase
Description : All the following statements about albinism are correct except (A) Tyrosine hydroxylase (tyrosinase) is absent or deficient in melanocytes (B) Skin is hypopigmented (C) It results in mental retardation (D) Eyes are hypopigmented
Description : Iron is present in all the following except (A) Peroxidase (B) Xanthine oxidase (C) Aconitase (D) Fumarase
Description : All of the following are iron-containing enzymes except (A) Carbonic anhydrase (B) Catalase (C) Peroxidase (D) Cytochrome oxidase
Description : The pentose phosphate pathway protects erythrocytes against hemolysis by assisting the enzyme: (A) Superoxide dismutase (B) Catalase (C) Glutathionic peroxidase (D) Cytochrome oxidase ENZYMES 149
Description : An enzyme involved in catabolism of catecholamines is (A) Dopa decarboxylase (B) Aromatic amino acid decarboxylase (C) Monoamine oxidase (D) Catechol oxidas
Description : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase
Description : In the synthetic pathway of epinephrine, disulfiram (antabuse) inhibits the enzyme: (A) Tyrosine hydroxylase (B) Dopamine β-hydroxylase (C) DOPA decarboxylase (D) N-methyl transferase
Description : For Catecholamine biosynthesis the rate limiting enzyme is (A) DOPA decarboxylase (B) DOPAMINE β-hydroxylase (C) Tyrosine hydroxylase (D) Phenylalanine hydroxylase
Description : Phenylalanine is the precursor of (A) L-DOPA (B) Histamine (C) Tyrosine (D) Throxine
Last Answer : C
Description : Albinism is a congenital disorder resulting from the lack of which enzyme? (a) Tyrosinase (b) Xanthine oxidase (c) Catalase (d) Fructokinase
Last Answer : (a) Tyrosinase
Description : All the following statements about phenylketonuria are correct except (A) Phenylalanine cannot be converted into tyrosine (B) Urinary excretion of phenylpyruvate and phenyllactate is increased (C) It ... diet (D) It leads to decreased synthesis of thyroid hormones, catecholamines and melanin
Description : Which of the following amino acids produce a vasoconstrictor on decarboxylation? (A) Histidine (B) Tyrosine (C) Threonine (D) Arginine
Description : The sequential steps in the conversion of tyrosine to epinephrine are (A) Ring hydroxylation-decarboxylation-side chain hydroxylation-N-methylation (B) Side chain hydroxylation-decarboxylation- ... chain hydroxylation-N-methylation (D) N-methylation-decarboxylation-ring and side chain hydroxylation
Description : The rate limiting step in the biosynthesis of catecholamines is (A) Decarboxylation of dihydroxyphenylalanine (B) Hydroxylation of phenylalanine (C) Hydroxylation of tyrosine (D) Oxidation of dopamine
Description : The following enzymes on the left are responsible for the synthesis of the neurotransmitters on the right: a. monoamine oxidase: noradrenaline b. cholinesterase: acetylcholine c. catechol-o-methyl transferase: dopamine d. dopa decarboxylase: adrenaline
Last Answer : dopa decarboxylase: adrenaline
Description : Following events occur in the cytoplasm and not inside storage vesicles, except (a) Conversion of tyrosine to dopa (b) Conversion of dopa to dopamine (c) Conversion of dopamine to norepinephrine (d) Conversion of dopamine to 3,4 dihydroxy phenyl acetic acid
Last Answer : Ans: C
Description : The rate limiting enzyme in the synthesis of catecholamines is: A. Tyrosine hydroxylase B. Dopa decarboxylase C. Dopamine β-hydroxylase D. Noradrenaline N-methyl transferase
Last Answer : A. Tyrosine hydroxylase
Description : The deficiency of copper decreases the activity of the enzyme: (A) Lysine oxidase (B) Lysine hydroxylase (C) Tyrosine oxidase (D) Proline hydroxylase
Description : Hormones thyroxine, adrenaline and the pigment melanin are formed from (a) tyrosine (b) proline (c) tryptophan (d) glycine.
Last Answer : (a) tyrosine
Description : Decarboxylation of α-keto acids requires (A) Thiamine pyrophosphate, FAD, NAD+ (B) Flavin mononucleotide (C) NADP+ (D) NAD+ only
Description : Oxidative decarboxylation of pyruvate requires (A) NADP+ (B) Cytichromes (C) pyridoxal phosphate (D) COASH
Last Answer : D
Description : Methyl dopa decreases blood pressure by (A) Inhibiting the synthesis of catecholamines (B) Antagonising the action of aldosterone (C) Stimulating the release of renin (D) Inhibiting the breakdown of angiotensin
Description : The enzyme dopamine β-oxidase which catalyses conversion of dopamine to norepinephrine requires (A) Vitamin A (B) Vitamin C (C) Vitamin E (D) Vitamin B12
Description : Conversion of tyrosine to dihydroxyphenylalanine is catalysed by tyrosine hydroxylase which requires (A) NAD (B) FAD (C) ATP (D) Tetrahydrobiopterin
Description : The conversion of alanine to glucose is termed (A) Glycolysis (B) Oxidative decarboxylation (C) Specific dynamic action (D) Gluconeogenesis
Description : A deficiency of copper effects the formation of normal collagen by reducing the activity of which of the following enzyme? (A) Prolyl hydroxylase (B) Lysyl oxidase (C) Lysyl hydroxylase (D) Glucosyl transferase
Description : Insulin degradation of disulfide bond formation is effected by (A) Pyruvate dehydrogenase (B) Xylitol reductase (C) Gutathione reductase (D) Xanthine oxidase
Description : The following are the functions of copper: (A) Constituent of cytochromes (B) Catalase (C) Tyrosinase (D) All of these
Description : An amino acid that does not take part in α helix formation is (A) Histidine (B) Tyrosine (C) Proline (D) Tryptophan
Description : Most of the ammonia released from L-αamino acids reflects the coupled action of transaminase and (A) L-glutamate dehydrogenase (B) L-amino acid oxidase (C) Histidase (D) Serine dehydratase
Description : Selenium is a constituent of (A) Glutathione reductase (B) Glutathione peroxidase (C) Catalase (D) Superoxide dismutase
Description : Hydrogen peroxide may be detoxified in the absence of an oxygen acceptor by (A) Peroxidase (B) Catalase (C) Both (A) and (B) (D) None of these
Description : Iron-pophyrin is present as prosthetic group in (A) Cytochromes (B) Catalases (C) Peroxidase (D) None of these
Description : The iron containing nonporphyrin is (A) Hemosiderin (B) Catalase (C) Cytochrome C (D) Peroxidase
Description : The sparing action of methionine is (A) Tyrosine (B) Cystine (C) Arginine (D) Tryptophan
Description : Dopa decarboxylase is inhibited by (A) Epinephrine (B) Norepinephrine (C) α−Methyldopa (D) None of these
Description : Immediate precursor of epinephrine is (A) Metanephrine (B) Norepinephrine (C) Dopa (D) Dopamine
Description : Blood brain barrier can be crossed by (A) Epinephrine (B) Dopamine (C) Dopa (D) All of these
Description : MSH causes (A) Dispersal of melanin granules in melanocytes (B) Increase in melanin concentration in melanocytes (C) Decerease in melanin concentration in melanocytes (D) Increase in number of melanocytes
Description : Retina contains this photosensitive pigment: (A) Rhodopsin (B) Opsin (C) Retinol (D) Melanin
Description : The highest concentration of cystine can be found in (A) Melanin (B) Chondroitin sulphate (C) Myosin (D) Keratin
Description : Tryptophan could be considered as precursor of (A) Melanotonin (B) Thyroid hormones (C) Melanin (D) Epinephrine
Description : The fo l low ing substances are ce l l inclusions except (A) Melanin (B) Glycogen (C) Lipids (D) Centrosome
Description : In which one of the following enzymes, is copper necessarily associated as an activator? (a) Carbonic anhydrase (b) Tryptophanase (c) Lactic dehydrogenase (d) Tyrosinase
Last Answer : (d) Tyrosinase