Biochem - WLB Flashcards
What is the rate-limiting enzyme in purine synthesis?
Glutamine PRPP Amidotransferase
What is the rate-limiting enzyme in pyrimidine synthesis?
Carbamoyl phosphate synthetase II (CPS-2)
What are the sources of carbon in the synthesis of purines?
CO2 + Glycine + THF
What are the sources of carbon in the synthesis of pyrimidines?
CO2 + Aspartate
Which medication inhibits ribonucleotide reductase?
Hydroxyurea
Which medication inhibits dihydrofolate reductase?
Trimethoprim (in prokaryotes) and Methotrexate (in eukaryotes)
Which medication inhibits thymidylate synthase?
5-Fluorouracil
Which medication inhibits inosine monophosphate dehydrogenase?
Mycophenolate
Which medication inhibits PRPP amidotransferase?
6-Mercaptopurine
What accounts for the positive charge of histones?
Lysine + Arginine
What accounts for the negative charge of DNA?
Phosphate groups
How many adenine residues are found in a molecule of DNA if ONE strand contains A=2000, G=500, C=1500, and T=1000?
3,000 adenine residues
remember DNA is a double helix: one strand has 2000 and the complementary strand has 1000 which are paired to thymine
What strand of DNA nucleotides opposes this DNA strand: 5’-ATTGCGTA-3’?
5’-TACGCAAT-3’
How does UV radiation damage DNA?
makes pyrimidine dimers on same strand
Which eukaryotic DNA polymerase replicates the lagging strand?
DNA polymerase Alpha
Which eukaryotic DNA polymerase synthesizes RNA primers?
DNA polymerase Alpha
Which eukaryotic DNA polymerase repairs DNA?
DNA polymerase Beta
Which eukaryotic DNA polymerase replicates mitochondrial DNA?
DNA polymerase Gamma
Which eukaryotic DNA polymerase replicates the leading strand?
DNA polymerase Delta
Which structural motifs allow proteins to bind to DNA?
Helix-loop-helix
Helix-turn-helix
Zinc finger
Leucine zipper protein
What amino acid is encoded by the most common start codon?
Methionine (AUG)
What is the difference between an intron and an exon?
Intron => non-coding region, gets spliced out and stays in the nucleus
Exon => coding region, gets transcribed
Production of what enzyme is regulated by the lac operon?
Beta-galactosidase
What two proteins regulate the lac operon?
CAP (catabolite activating protein) and lac repressor