Molecular Biology Flashcards

1
Q

Name the drugs that cause drug induced lupus

A

Isoniazid (tb drug)
Hydrolazine (vasondilatador for high blood pressure)
Procainamid (anti arritmic)

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2
Q

What’s an histone

A

DNA protein (H1; H2A; H2B; H3; H4)
H1 keeps them together : the rest binds and form octameter (8 histones)

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3
Q

What causes drug induced lupus?

A

Anti histones antibodies

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4
Q

Which aa gives Nitrogen to Purines?

A

Glutamine (2 N)
Aspartate ( 1N to the 6th ring)
Glycine (carbons and N)

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5
Q

What are the carbon sources of Purines?

A

CO2 (1 in 6C ring)
Tetrahydrofolate (2; 1 to each ring)
Glycine (2; each ring)

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6
Q

Drugs that inhibit IMP dehydrogenase

A

Ribavirin
Mycophenolate

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7
Q

Antiviral that blocks conversion of IMP to GMP

A

Rivabirin,
Inhibits guanine nucleotides

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8
Q

Immunosuppressant that inhibits IMP dehydrogenase in white cells

A

Mycophenolate

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9
Q

Chemotherapy agent that mimics hypoxantine/ guanine to inhibit the novo synthesis

A

Azathioprine -> 6-mercaptopurine [6-mp])
Creates thioniosinic acid
(Decreases DNA synthesis by decreasing IMP/GMP/AMP)

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10
Q

Enzyme deficient or disfunctional in the severe combined immunodeficiency syndrome

A

Adenosine deaminase
(Purine -Adenine- breakdown pathway)

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11
Q

Inhibits xanthine oxidase

A

Allopurinol
(Tx for gout )

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12
Q

Lesch Nyhan syndrome

A

X linked deficiency of HGPRT

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13
Q

Excess De Novo synthesis (PRPP -IMP)

A

Lesch nyhan syndrome

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14
Q

Source of C an N of pyrimidine rings

A

Carbamoil Phospate - 1 C and 1 N
Aspartate - 3 C and 1 N

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15
Q

Defect in UMP synthase

A

Orotic aciduria

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16
Q

Synthesis of pyrimidine bases

A

Glutamine -> catbamoil phosphate -> Orotic acid ——-—->UMP -> CMP - TMP
———————————————————————UMP synthase

17
Q

Orotic Aciduria
(5 characteristics)

A
  • Autosomal Recessive
  • loss of pyrimidines
  • Orotic acid in urine
  • megaloblastic anemia (folate deficiency) that does NOT respond to folate treatment
  • grow retardation
18
Q

Treatment for Orotic aciduria

A

Uridine (bc bypasses the UMP synthase)

19
Q

Ornithine transcarbamylase (OTC) deficiency

A

X-linked
Increases carbamoyl phosphate -> high Orotic acid -> Orotic aciduria
High amonia levels

20
Q

Differences between OTC deficiency and Orotic Aciduria

A

In OTC deficiency: - high Orotic acid levels both urine and plasma
- high ammonia (due to impaired urea synthesis)
-Encephalopathy

Orotic aciduria :- megaloblastic anemia non responding to folate
- high Orotic acid levels both plasma and urine

21
Q

Chemotherapy agent Ara-C (cytarabine) Mechanism of action

A

Mimics dCTP (pyrimidine analog)
Inhibits DNA polymerase

22
Q

Hydroxyurea mechanism of action

A

Inhibits ribonucleotide reductase

(Causes increased fetal hemoglobin by unclear mechanism )

23
Q

Uses of hydroxyurea

A
  • polycythemia Vera; essential thrombocytosis -> blocks formation of deoxynucleotides
    -sickle cell anemia(increase hbF)
24
Q

How folate regulates the conversion of dUMP to dTMP

A

By giving 1 C through the enzyme thymidylate synthase; the C comes from N5; N10 tetrahydrofolate

[folate -> dehydrofolate -> Tetrahydrofolate -> N5 N10 tetrahydrofolate]

25
Q

Chemotherapy agent that inhibits thymidylate synthase and blocks dTMP

A

5-FU(floururacil)
(Cancer cells can’t synthesize thymine so they die)

26
Q

Side effect of methotrexate use

A

Bone marrow suppression
Can be rescue with Leucovorin (folinic acid converted into Tetrahydrofolate)

27
Q

Immunosuppressant that inhibits dihydrofolate reductase

A

Methotrexate
(Dihydrofolate reductase converts dihytrofolate to Tetrahydrofolate and Tetrahydrofolate is needed to convert dUMP to dTMP)

28
Q

Antibiotics that blocks (bacterial DNA )Tetrahydrofolate synthesis

A

Sulfonamides -> inhibits dihydropteroate synthase
Trimethoprim -> inhibits dihydrofolate reductase (the bacterial one)

29
Q

What’s required to generate THF from N5 Methyl THF

A

Vitamin B12

30
Q

Difference between folate and b12 deficiency

A

Fiolate: megaloblastic anemia ; no neurological impairment
B12= demyelination . (Can overcome /b12 deficiency with high folate intake)

31
Q

How to tell apart a B12 vs a B9 deficiency

A

In both homocysteine levels will be high (bc you need them both to convert homocysteine to methionine)

In B12 deficiency methymalonic, MMA, acid levels will be high ( bc you need B12 to convert MMA to succinyl coA)

32
Q

Drug induced Megaloblastic anemia

A
  • Methotrexate
  • 5-Floururacil
  • hydroxyurea
33
Q

II; VII; IX;X

A

For vitamin K