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Biochem PLE | Des > Nitrogen Metabolism > Flashcards

Nitrogen Metabolism Flashcards

1
Q

How many grams of CHON are turnover per day?

A

300-400g/day

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2
Q

Sum of all CHON degraded and resynthesized from AA

A

Amino acid pool

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3
Q

There are the energy producing metabolic pathways

A

Glycolysis

Krebs cycle

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4
Q

What is the 1st step in 1st phase of AA catabolism

A

Transamination

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5
Q

Second step in AA catabolism

A

Oxidative deamination

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6
Q

Enzyme in transamination

A

Amino transferase

A ketoglutarate –> glutamate

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7
Q

Coenzyme in transamination

A

Pyridoxal phosphate - Vit B6

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8
Q

Enzyme in

Glutamate –> ammonia/ NH3

A

Glutamate dehydrogenase

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9
Q

Enzyme in

Glutamate + NH3 = glutamine

A

Glutamine synthetase

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10
Q

Glutamine –> NH3

A

Glutaminase

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11
Q

Where does urea cycle occur? In body and cell

A

Liver

Mitochondria & cytosol

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12
Q

Rate limiting step in urea cycle?

A

Nh3 + Co2 –> carbamoyl phosphate

Carbamoyl phosphate synthetase 1

Allosteric activator: n-acetylglutamate

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13
Q

MC heriditary hyperammonemia

A

Ornithine transcarbomylase deficiency

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14
Q

most severe hereditary hyperammonemia

A

Carbamoyl phosphate synthetase -1 deficiency

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15
Q

Purely ketogenic AA

A

Lysine

Leucine

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16
Q

Glucogenic and ketogenic

A

TRY PHilippine ISlands. TY

Tryptophan
Phenylalanine
Isoleucine
Tyrosine

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17
Q

Congential deficiency of HOMOGENTISATE OXIDASE

In the degradative pathway of tyrosine leading to build up of homogentisic acid

A

Alkaptonuria

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18
Q

Urine turns black on standing, ochronosis (connective tissue is dark), athralgias
Benign

A

Alkaptonuria

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19
Q

Tx of alkaptonuria

A

Reduce phenylalanine and tyrosine in diet

Vit c for older children and adults

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20
Q

What enzyme is absent in albinism?

A

Tyrosinase

Albinism: risk for skin ca

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21
Q

Most common deficiency in homocystinuria

A

Cystathionine B-synthase

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22
Q

Homocystinuria is a defect in what AA

A

Methionine

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23
Q

Coenzyme of methionine synthase

A

Methylcobalamin

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24
Q

Coenzyme of cystathionine B-synthase

A

Pyridoxal phosphate

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25
Q 
What condition has
Ectopia lentis (downward displacement)
MR
MI
Stroke
A

Homocystinuria

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26
Q

Treatment for homocystinuria

A

Restriction of methionine
Limit eggs, fish, meat
Supplementation: B6, B12, folate

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27
Q

Cystinuria is an inherited defect of renal tubular amino acid transporter for _____ in PCT of kidneys

A 
COLA
Cystine
Ornithine
Lysine
Arginine
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28
Q

What calculi found in cystinuria

A

Staghorn calculi

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29
Q

Tx for cystinuria

A

Acetazolamide

To alkalanize the urine

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30
Q

Methylmalonic acidemiia is a deficiency in?

A

Methylmalonyl CoA mutase

Defect in conversion of methlymalonyl CoA to succinyl CoA

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31
Q

Presents with seizure, encephalopathy, stroke (1 mo- 1 yr)

Hypotonia, lethargy, failure to thrive, hepatosplenomegaly, monilial infx

A

Methylmalonic acidemia

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32
Q

Tx for Methylmalonic acidemia

A

Protein restricted diet
(0.5-1.5 g/kg/d)
With L-carnitine and cobalamin supplementation

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33
Q

Branched amino acids

A

VIL
Valine
Isoleucine
LEUcine

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34
Q

Blocked degradation of branched AA due to a deficiency in

A

A-ketoacid dehydrogenase complex

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35
Q

Tx for maple syrup urine dse

A

Dietary restriction

36
Q

Rate limiting step in heme synthesis

A

Formation of aminolevulinic acid

Glycine + succinyl CoA –> aminolevulinic acid

37
Q

Enzyme?

Glycine + succinyl CoA –> aminolevulinic acid

A

ALA synthase

38
Q

Co factor in formation in aminolevulinic acid

A

Pyridoxine

B6

39
Q

This causes inactivation of ALA dehydratase and ferrochelatase

A

Lead poisoning

40
Q

What condition has microcytic, hypochromic anemia
With basophilic stippling of RBCs
Headache, memory loss
Peripheral neuropathy, claw hand, wrist drop, GI symptoms,

A

Lead poisoning

41
Q

Disorder due to abnormalities in pathway of biosynthesis of heme

A

Porphyrias

Result in accumulation and increased excretion of porphyrins or porphyrin precursors

42
Q

Most common porphyrias

A

Porphyria cutanea tarda

43
Q

Presents with photosensitivity, neuropsych symptoms, abdominal pain

A

Porphyrias

44
Q

Enzyme in formation of bilirubin in heme degradation

A

Heme oxygenase

Heme –> biliverdin (green) –> bilirubin (red orange)

45
Q

Bilirubin transported to the liver in the blood binds to

46
Q

In heme degradation

Bilirubin is conjugated to 2 mol of

A

Glucoronic acid

47
Q

Enzyme ini formation of bilirubin diglucoronide

A

Bilirubin glucuronyltransferase

48
Q

Deficient in Crigler-Najjar I and II

and Gilbert syndrome

A

Bilirubin glucuronyltransferase

49
Q

Results from an elevated level of plasma bilirubin

50
Q

Used to measure bilirubin in serum

A

Van den Bergh reaction

51
Q

Involved in well fed state

52
Q

Involved in fasting state

53
Q

Located at B cells of islets of Langerhans

54
Q

Located at alpha cells of islets of Langerhans

55
Q

2 polypeptide chains with 51 AA linked together by 2 disulfide bridges

56
Q

Single polypeptide chain with 29 AA

57
Q

2nd messenger of insulin

A

Tyrosine kinase

58
Q

2nd messenger of glucagon

59
Q

Stimulus for secretion
Ingestion of glucose and AA
Cholecystokinin and gastric inhibitory polypeptide

60
Q

Stimulus for secretion

Actual or potential hypoglycemia

61
Q

Enzyme in phosphorylation

A

Pyruvate kinase (glycolysis)

62
Q

Enzyme in dephosporylation

A

Glycogen synthase (glycogenesis)

63
Q

In fed state brain uses _____ exclusively as fuel

64
Q

In fasting state brain uses ______ and ______ as fuel

A

Glucose

Ketone bodies

65
Q

Erythrocytes uses ____ exclusively as fuel during well fed state

66
Q

In fasting state

Erythrocyte uses _____ as fuel

67
Q

This provides energy source and snynthesize ketone bodies during fasting state

A

Beta oxidation

68
Q

Pathway that produces NADPH

69
Q

_____ for beta oxidation

70
Q

____ for gluconeogenesis

71
Q

During marathon and fasting this provides skeletal muscle with energy (major source)
May also use ketone bodies

A

Fatty acids

72
Q

Principle site of metabolism of branched chain amino acids

A

Skeletal muscle

73
Q

Can act as energy store for short term demands

A

Phosphocreatine

74
Q

Iron transport protein in plasma

A

Transferrin

75
Q

MC micronutrient deficient worldwide

A

Iron deficiency anemia

76
Q

Iron overload syndrome with progressive hemosiderosis and resulting organ damage

May lead to liver cirrhosis, liver cancer, DM, cardiomyopathy, hyperpigmentation of skin, endocrine disorders and joint pain

A

Hemochomatosis

77
Q

Treatment for hemochromatosis

A

Repeated phlebotomy

78
Q

Most abundant trace mineral in the body after iron, with total body stores of about 1.5 to 2.5g

79
Q

Leads tp dermatitis and poor wound healing, hair loss, neuropsychiatric impairments, decreased taste acuity
And in children, poor growth and testicular atrophy

A

Zinc deficiency

80
Q

Presents with microcytic hypochromic anemia, leukopenia, hemorrhagic vascular changes, bone demineralization, hypercholesterolemia, neurological problems
Seen in: pts receiving total parenteral nutrition and in infants

A

Copper deficiency

81
Q

Deficiency of an ATP-dependent membrane transporter for copper
Growth retardation, mental deficiency, seizures, arterial aneurysms, bone demineralization, brittle hair

A

Menkes syndrome

82
Q

Intestinal absorption of copper is intact but its biliary excretion is blocked
Copper accumulation in liver and brain, with resulting liver damage, neurological deterioration, or both

A

Wilson disease

83
Q

Kayser-fleisher rings

A

Wilson disease

84
Q

Treatmetn for wilson disease

A

D-penicillamine

Which forms a soluble excretable copper complex

85
Q

Excess can cause psychosis and parkinsonism

A

Manganese madness

86
Q

This occurs in few oxidase enzymes, including xanthine oxidase

A

Molybdenum

87
Q

Low selenium content causing cardiomyopathy

A

Keshan disease

Biochem PLE | Des (5 decks)

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