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22 Cards in this Set
- Front
- Back
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What is DNA methylation and what does it do?
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Template strand C & A are methylated so that mismatch repair enzymes can ID old strand from new strand.
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what is histone acetylation?
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Addition of acetyl groups relaxes DNA coiling and allows transcription.
A-cetylation --> makes DNA A-ctive |
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Which nucleobase has a methyl group?
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Thymine
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Which nucleobase has a ketone group?
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Guanine
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What is the chemical difference between cytosine and uracil?
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Cytosine has an amino group.
Cytosine is made from Uracil by addition of an amino group (taken from Glutamine) |
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What are the amino acids necessary for purine synthesis?
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Glycine
Aspartate Glutamine (A & G & G needed to make A & G) |
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What are the characteristics of the H-bonds in a DNA helix?
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A-T = 2 H-Bonds
C-G = 3 H-Bonds (higher melting point) |
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What is the difference in order between Purine and Pyrimidine synthesis?
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Purines = PRPP first, then BASE
Pyrimidines = BASE first, then PRPP --> then modify base (3 steps like a pyramid) |
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What 2 metabolic pathways is Carbomoyl phosphate involved in?
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1) Pyrimidine synthesis
2) Urea cycle |
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What are the causes of ↑ Orotic acid in urine?
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1) OTC deficiency:
- ornithine transcarbamoylase deficiency in urea cycle → accumulate Carbamoyl phosphate → Orotic acid NOTE: also has ↑ NH3 2) Inability to convert Orotic acid ↑ UMP in Pyrimidine synthesis |
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What are the causes of Orotic acidemia?
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Enzyme defects:
1) Orotic Acid Phophoribosyltransferase 2) Orotidine 5'-Phophate Decarboxylase Both inhibit Orotic Acid + PRPP → UMP in Pyrimidine synthesis |
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What is the cause of megaloblastic anemia that doesn't improve with B12 or Folate?
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Orotic Aciduria
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What is the treatment for Orotic aciduria?
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Simply give PO Uridine
(bypass the holdup preventing conversion of Orotic acid → UMP) |
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What are the reactants used by DHFR to make THF?
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- DHF
- NADPH - H+ (the 2 H's are added to DHF to make THF) Rx's that block: - Eukaryotes = MTX - Prokaryotes = TMP |
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What does thymidylate synthase do? What inhibits it?
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Converts: dUMP → dTMP
(uses THF to add a methyl group to U → T) Rx = 5-FU (5-flurouracil) |
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What purine salvage problem can cause immune problems? How?
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Adenosine deaminase deficiency
→ SCID ADA converts Adenosine → Inosine (which can → uric acid) w/o ADA, Adenosine builds up and ↑ATP/dATP neg f/b on Ribonuclotide reductase → prevent DNA synthesis → ↓ lymphocytes |
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What are the functions of xanthine oxidase? What Rx inhibits it?
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1) Hypoxanthine → Xanthine
2) Xanthine → Uric Acid 3) Metabolizes Drugs - 6-MP (Chemo) - Azothioprine (Immuno) Rx = Allopurinol |
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What causes Lesch-Nyhan syndrome?
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XLR abscence of HGPRT
(hypoxanthine-guanine phospho-ribosyl-transferase) w/o HGPRT, unable to salvage either guanine (→GMP) or hypoxanthine (→IMP) leading to: 1) ↑ Uric Acid 2) ↑ Purine synthesis |
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What are the findings of Lesch-Nyhan syndrome?
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1) Retardation
2) Self-mutilation 3) Aggression 4) Choreoathetosis (involuntary writhing movements) 5) Hyperuricemia → Gout |
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What are drugs that inhibit DNA topoisomerases (Pro- and Eukaryotic)
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Prokaryotes = Fluoroquinolones (prokaryotic topoisomerase II)
Eukaryotes = eTOPoside (used in cancer tx) |
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What autoimmune disease involves DNA topoisomerase? What is the antibody?
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Diffuse Scleroderma (systemic sclerosis)
Ab = Anti-Scl-70 NOTE: CREST Scleroderma involves anti-centromere Ab |
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What direction do the following enzymes act:
- DNA Poly I - DNA Poly III - Telomerase |
- DNA Poly I = exonuclease 5→3
- DNA Poly III: - polymerase = 5→3 - EXONUCLEASE= 3→5 - Telomerase = 5→3 |
