4/8 biochem review Flashcards
(150 cards)
Amino acids necessary for purine synthesis:
She’s not PUR(e)ine if she GAGs.
- Glycine
- Aspartate
- Glutamine
- carbamoyl phosphate synthetase 1 = which reaction?
- carbamoyl phosphate synthetase 2 = which reaction?
CPS1 = urea cycle CPS2 = pyrimidine synthesis
mycophenolate
- mech:
- same mech as which other drug?
- inhibit IMP dehydrogenase.
- ribavirin.
ribavirin
- mech:
- same mech as which other drug?
- inhibit IMP dehydrogenase.
- mycophenolate.
hydroxyurea
-mech:
-inhibits ribonucleotide reductase, inc. HbF.
Azathioprine & 6-MP
-mech:
-inhibit PRPP amidotransferase (de novo purine synth).
PRPP amidotransferase
- what does it do?
- what inhibits it?
- PRPP => IMP (purine synth).
- inhibited by IMP, AMP, GMP, azathioprine, 6-MP.
*inhibited by purines bc thats what it makes.
IMP dehydrogenase
- whats it do?
- what inhibits it?
- IMP => GMP (purine synth).
- mycophenolate, ribavirin.
Orotic aciduria
- which step in which pathway is messed up?
- Tx:
- pyrimidine synth: orotic acid => UMP.
- uridine monophosphate (basically just give UMP so you skip the step w/the faulty enzyme).
Which bases does xanthine oxidase convert to xanthine and then uric acid?
Guanine & hypoxanthine.
HGPRT
- this enzyme converts what to what?
- its products have neg. feedback on what enzyme?
Guanine & hypoxanthine = bases.
-HGPRT adds a ribose & phosphate to these bases and makes nucleotide monophosphates = GMP & IMP.
-GMP & IMP (& AMP) have (-) feedback on amidotransferase of purine synthesis. You’re salvaging purines so no need to make more.
Adenosine deaminase deficiency
- adenosine deaminase catalyzes which reaction?
- what builds up in this enzyme deficiency?
- build up of this inhibits what enzyme?
- Adenosine => inosine.
- Excess ATP and dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reductase, prevents DNA synthesis and thus dec. lymphocyte count.
Genetic code:
-which AAs are only coded by one codon?
-methionine and tryptophan encoded by only 1 codon (AUG and UGG, respectively).
Genetic code is universal except where?
human mitochondria.
Prok. vs Eukaryote.
-which one has multiple origins of replication?
-eukaryote.
DNA Pol
-builds in what direction?
5’ => 3’
-you add things to the 3’ hydroxyl group.
Which prok. DNA Pol has 5’ to 3’ exnuclease?
-what does it use it for?
DNA Pol I
-excise RNA primers.
Telomerase
-An ____ dependent _____ polymerase.
RNA dep. DNA polymerase.
*so its a reverse transcriptase.
Purine => purine or pyr => pyr mutation: called what?
transition
purine => pyrimidine or pyr => pur mutation: called what?
transversion
Ataxia telangiectasia
- whats dysfunctional here?
- what are these pts vulnerable to?
Nonhomologous end joining: method for fixing ds breaks.
*ionizing radiation causes ds breaks.
Incoming nucleotide for DNA synth: how many phosphates does it have?
3
mRNA read in what direction?
5’ to 3’
Protein synthesis in what direction?
N-terminus to C-terminus.