MCB NBME Shelf Random Questions with correct Answers

alpha-amanitin - Answer- Inhibits RNA poly II (mRNA synthesis) or RNA poly II in high concentrations 3' - 5' exonuclease activity - Answer- All DNA polymerase What removes primers in eukaryotes - Answer- RNAase H What removes primers in prokaryotes - Answer- DNA poly I What 2 amino acids are not found in alpha helices - Answer- proline and glycine (bulky) Deamination of Cytosine yields? - Answer- Uracil Alkylated G pairs with? - Answer- T X-rays form what type of DNA damage? - Answer- double strand breaks UV rays form what type of DNA damage? - Answer- pyrimidine dimers (specifically T-T) Which topoisomerase is a good target for antibiotics? - Answer- Type II Topoisomerase (gyrase) - no equivalent in eukaryotes DNA interaction with histones leads to what type of supercoiling? - Answer- Negative Xeroderma pigmentosum is a disease caused by a mutation in what mechanism? - Answer- Nucleotide excision repair. XP-C most common Cockayne syndrome is a disease caused by what mechanism - Answer- Transcription-coupled nucleotide excision repair Splice donor site - Answer- 5' intron site Splice acceptor site - Answer- 3' end intron Streptomycin - Answer- Binds to 30S, inhibits initiation of translation Puromycin - Answer- Binds to A-site and participates in peptide bonding - premature termination Tetracyclin - Answer- Blocks A-site Chloramphenicol - Answer- Binds to large subunit - blocks bacterial peptidyl transferase Erythromycin - Answer- Binds to large subunit - blocks translocation Diptherias & pseudomonas - Answer- Blocks eEF2 via ADP-ribosylation Ricin - Answer- Depurinates adenosine in 28S rRNA, blocking peptidyl transferase activity Lac Operon - Answer- Glucose binds CAP (bad), Lactose removes repressor (good) Tamoxifen - Answer- Competitive antagonist to estrogen for estrogen receptor - causing it to bind co-repressor instead of co-activator Helix turn helix rich in what amino acids? - Answer- QNERK eIF2 and heme/iron relationship - Answer- When heme/iron is present, kinase is inhibited and eIF2 is stable Ferritin/transferrin - Answer- Presence of iron takes of binding protein from ferritin and transferrin. Ferritin translation is blocked and transferrin translation is stabilized Enzyme affected in Menke's disease/Ehlers-Danlos type IX - Answer- Lysyl Oxidase Rifampin - Answer- Blocks transcription initiation by binding to RNA polymerase actinomycin - Answer- Inhibits transcription elongation by binding to template strand Alpha-1-antitrypsin - Answer- inhibits elastase. Mutated a1antitrypsin - COPD/emphysema