Amino Acid Metabolism — Flashcards

Flashcard 1: pulses are deficient in _____ amino acids

Answer: cysteine and methionine

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Flashcard 2: cereals are deficient in _____ amino acids

Answer: threonin and lysine

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Flashcard 3: taurine amino acid is essential for _____

Answer: axonal growth

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Flashcard 4: breast milk is rich in _____ essential amino acids

Answer: cysteine and taurine

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Flashcard 5: maize is deficient in _____ amino acids

Answer: tryptophan and lysine

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Flashcard 6: _____ amino acid is essential for premature children

Answer: cysteine

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Flashcard 7: _____ is a neurotransmitter derived from the amino acid glutamate

Answer: -Aminobutyric acid (GABA)

Flashcard 8: _____ may be converted to tyrosine via the enzyme phenylalanine hydroxylase (with tetrahydrobiopterin as a cofactor)

Answer: Phenylalanine

Flashcard 9: Carbamoyl phosphate synthetase I deficiency presents with _____ NH4+ and hyper-ammonemia

Answer: increased

Flashcard 10: Gyrate atrophy is a metabolic disorder due to the deficiency of _____ enzyme (OAT), resulting in an increase in serum ornithine.

Answer: ornithine aminotransferase

Flashcard 11: _____ may be combined with ornithine to form citrulline via the enzyme ornithine transcarbamylase

Answer: Carbamoyl phosphate

Flashcard 12: _____ may be converted to dopamine via the enzyme DOPA decarboxylase (with vitamin B6 as a cofactor)

Answer: Dihydroxyphenylalanine (DOPA)

Flashcard 13: _____ and valine are eventually broken down into propionyl-CoA via the enzyme branched-chain -ketoacid dehydrogenase

Answer: Isoleucine

Flashcard 14: Vitamins required for the conversion of serine to glycine are _____ and folic acid

Answer: pyridoxal phosphate (B6)

Flashcard 15: Hartnup disease is treated with a high-_____ diet and nicotinic acid (niacin)

Answer: protein

Flashcard 16: _____ (from tyrosine) may be converted to maleylacetoacetate via the enzyme homogentisate oxidase

Answer: Homogentisic acid

Flashcard 17: The urea cycle begins with _____, CO2, and 2 ATP

Answer: NH4+

Flashcard 18: In the first step of thyroid hormone synthesis, _____ is synthesized from tyrosine in the thyroid follicular cells

Answer: thyroglobulin

Flashcard 19: _____ is an obligate activator of carbamoyl phosphate synthetase I

Answer: N-acetylglutamate

Flashcard 20: In the first step of the urea cycle, CO2 and NH4+ are combined to form _____ via the enzyme carbamoyl phosphate synthetase I (requires 2 ATP)

Answer: carbamoyl phosphate

Flashcard 21: _____ is eventually broken down into acetyl-CoA via the enzyme branched-chain -ketoacid dehydrogenase

Answer: Leucine

Flashcard 22: _____ may be converted to melanin via the enzyme tyrosinase

Answer: Dihydroxyphenylalanine (DOPA)

Flashcard 23: Arginine may be broken down into _____ and urea via the enzyme arginase

Answer: ornithine

Flashcard 24: _____ may be converted to epinephrine via the enzyme phenylethanolamine-N-methyltransferase (with SAM as a cofactor) and stimulated by cortisol

Answer: Norepinephrine

Flashcard 25: In the liver, alanine transfers its NH3 group to _____, forming glutamate and pyruvate

Answer: -ketoglutarate

Flashcard 26: _____ may be converted to cystathionine via the enzyme cystathionine synthase (with B6 as a cofactor)

Answer: Homocysteine

Flashcard 27: Type _____ maple syrup urine disease (MSUD) results from the mutation in the genes encoding dihydrolipoyl transacylase.

Answer: II

Flashcard 28: _____ is converted to dihydroxyphenylalanine (DOPA) via the enzyme tyrosine hydroxylase (with tetrahydrobiopterin as a cofactor)

Answer: Tyrosine

Flashcard 29: In addition to enzyme deficiencies, homocystinuria may be caused by decreased affinity of _____ for pyridoxal phosphate (B6, active form)

Answer: cystathionine synthase

Flashcard 30: Phenylketones include _____, phenyllactate, and phenylpyruvate

Answer: phenylacetate

Flashcard 31: At the junction of the follicular cells and the follicular lumen, _____ residues of thyroglobulin react with I2 to form monoiodotyrosine (MIT) and diiodotyrosine (DIT)

Answer: tyrosine

Flashcard 32: In the muscle, glutamate transfers its NH3 group to _____, forming alanine and -ketoglutarate

Answer: pyruvate

Flashcard 33: What enzyme deficiencies may cause homocystinuria? _____ and methionine synthase deficiencies

Answer: Cystathionine synthase

Flashcard 34: Creatine is synthesized from _____, arginine, and methionine (GAM)

Answer: glycine

Flashcard 35: _____ disease is due to a deficiency of neutral amino acid transporters (especially tryptophan) in the proximal renal tubular cells and enterocytes

Answer: Hartnup

Flashcard 36: What are the 9 (10*) essential amino acids? _____ValineThreonineTryptophan IsoleucineMethionineHistidine Arginine* during periods of growthLysineLeucine

Answer: Phenylalanine

Flashcard 37: _____ urine is characteristically seen in multiple carboxylase deficiency.

Answer: Tomcat

Flashcard 38: _____ is also called the 22nd amino acid and is encoded by UAG

Answer: Pyrrolysine

Flashcard 39: Pyruvate is converted to _____ via the enzyme alanine aminotransferase (ALT) (Cahill cycle)

Answer: alanine

Flashcard 40: Ornithine transcarbamylase (OTC) deficiency presents with _____ NH4+ and hyper-ammonemia

Answer: increased

Flashcard 41: In the kidney, glutamine may be broken down into _____ and glutamate via the enzyme glutaminase

Answer: NH4+

Flashcard 42: In the liver, glutamate may transfer its NH3 to _____, forming aspartate and -ketoglutarate

Answer: oxaloacetate

Flashcard 43: Difference in proportion of _____ and Pheomelanin leads to difference in skin colours

Answer: Eumelanin

Flashcard 44: _____ is a metabolic disorder associated with black-colored urine after prolonged exposure to air

Answer: Alkaptonuria

Flashcard 45: After organification of I2, coupling between _____ may combine to form thyroxine (T4)

Answer: two molecules of DIT

Flashcard 46: _____ cleaves the amino acid arginine into citrulline and nitric oxide

Answer: NO synthase

Flashcard 47: The amino acid _____ is essential during periods of positive nitrogen balance

Answer: arginine

Flashcard 48: _____ and Histidine are semi-essential amino acids

Answer: Arginine

Flashcard 49: Argininosuccinate may be broken down into _____ and fumarate via the enzyme argininosuccinase

Answer: arginine

Flashcard 50: Once in target tissues, the enzyme _____ converts T4 to T3 by removing one atom of I2; a certain portion is also converted to reverse T3 (rT3) which is inactive

Answer: 5'-deiodinase

Flashcard 51: _____ may be generated via the "VOMIT" pathway:V: valineO: odd-carbon fatty acidsM: methionine I: isoleucineT: threonine

Answer: Propionyl-CoA

Flashcard 52: NH3 is excreted in the urine primarily in the form of _____ (from the liver) and NH4+ (from glutamine breakdown)

Answer: urea

Flashcard 53: In the liver, amino acids transfer their NH3 group to _____, forming glutamate and -ketoacids

Answer: -ketoglutarate

Flashcard 54: Methylmalonyl-CoA may be converted to _____ via the enzyme methylmalonyl-CoA mutase (with vitamin B12 as a cofactor)

Answer: succinyl-CoA

Flashcard 55: A positive _____ test may help in the diagnosis of cystine kidney stones

Answer: sodium cyanide nitroprusside

Flashcard 56: _____ may be combined with aspartate to form argininosuccinate via the enzyme argininosuccinate synthetase (requires 1 ATP)

Answer: Citrulline

Flashcard 57: Fumarylacetoacetate converts to _____ and Acetoacetate with the help of enzyme hydrolase

Answer: Fumarate

Flashcard 58: The amino acids _____ and arginine are positively charged at body pH (basic)

Answer: lysine

Flashcard 59: _____ is synthesized from L-arginine via NO synthase

Answer: NO

Flashcard 60: Urea has two nitrogen molecules, one from _____ and one from aspartate

Answer: NH3

Flashcard 61: Tyrosine converts to _____ with the help of enzyme aminotransferase

Answer: 4-OH phenylpyruvate

Flashcard 62: People with a genetic deficiency of _____ present with hypermethioninemia

Answer: /-methionine adenosyltransferase

Flashcard 63: The treatment for propionic acidemia is a low _____ diet that does not include valine, methionine, isoleucine, or threonine

Answer: protein

Flashcard 64: Glutathione is a tripeptide composed of _____, CystEine and Glycine

Answer: Glutamate

Flashcard 65: In the muscle, amino acids transfer their NH3 group to _____, forming glutamate and -ketoacids

Answer: -ketoglutarate

Flashcard 66: An odour of _____ is diagnostic of type 1 tyrosinemia and hypermethioninemia

Answer: boiled cabbage

Flashcard 67: _____ may be converted to methionine via the enzyme methionine synthase (with methyl-THF and vitamin B12 as cofactors)

Answer: Homocysteine

Flashcard 68: After release from iodinated thyroglobulin, MIT and DIT are _____ by the enzyme thyroid deiodinase, reproducing I- and tyrosine

Answer: deiodinated

Flashcard 69: _____ is a dipeptide that is a marker of meat consumption

Answer: Anserine

Flashcard 70: _____ is a dipeptide that can be found in excitable tissues like brain and muscle.

Answer: Carnosine

Flashcard 71: Amine hormones are derivatives of the amino acid _____

Answer: tyrosine

Flashcard 72: All amino acids undergo transamination except: _____

Answer: Proline, Lysine, Threonine and Hydroxyproline (4)

Flashcard 73: Hyperammonemia type 1 occurs due to deficiency of the enzyme _____

Answer: CPS-1

Flashcard 74: _____ is a purely glucogenic amino acid.

Answer: Alanine

Flashcard 75: Which enzyme is involved in oxidative deamination?_____

Answer: Glutamate dehydrogenase

Flashcard 76: _____, a derivative of histidine is found to be unusually low in urine in patients of Wilson's disease

Answer: 3-methyl-histidine

Flashcard 77: Which amino-acid metabolism disorder clasically presents with sweaty feet?_____

Answer: Isovaleric aciduria

Flashcard 78: Patients treated with nitisinone may develop corneal crystals of _____ which can be reduced by strict dietary control

Answer: tyrosine

Flashcard 79: Taurine is biosynthesized from _____.

Answer: cysteine

Flashcard 80: Phenylalanine levels are _____ in a patient of Segawa syndrome, after a phenylalanine loading test (100mg/kg)

Answer: increased

Flashcard 81: _____ in eukaryotes is also known as 21st amino acid

Answer: Selenocysteine (Sec)

Flashcard 82: Plasma levels of _____ are elevated in gyrate atrophy of retina and choroid.

Answer: ornithine

Flashcard 83: Urine FeCl3 test done for PKU detects the presence of _____

Answer: Phenylpyruvate

Flashcard 84: How does hyperammonenemia deplete alpha-ketoglutarate?_____

Answer: 1. the excess free ammonia binds to glutamate and forms glutamine2. To compensate for the reduced glutamate, alpha-ketoglutarate is aminated to glutamate.

Flashcard 85: The amount of _____ excreted in the urine is directly proportional to muscle mass

Answer: creatinine

Flashcard 86: What kind of odour is seen in Hawkinsinuria?_____

Answer: Swimming pool

Flashcard 87: HHH syndrome occurs due to the deficiency of enzyme _____

Answer: ornithine permease

Flashcard 88: N-Formimino glutamate (FIGLU) is an intermediate in the metabolism of _____.

Answer: histidine

Flashcard 89: What is the most common acquired cause for increased plasma tyrosine levels?_____

Answer: Transient tyrosinemia of the newborn

Flashcard 90: Which amino acids present in human milk help in neuromodulation and neurotransmission?_____

Answer: Taurine and cysteine

Flashcard 91: Phenylketonuria can be treated by large neutral amino acid supplementation, or use of commercially available BH4 also called as _____

Answer: sapopterin

Flashcard 92: A musty odour in PKU is due to _____ in sweat.

Answer: phenylacetate

Flashcard 93: Which amino acid has an indole group?_____

Answer: Tryptophan

Flashcard 94: Which amino-acid is formed after co-translational modification?_____

Answer: Selenocysteine

Flashcard 95: Homocarnosine is made up of _____ and GABA.

Answer: histidine::AA