USLME – BIOCHEMISTRY EXAM 2024 WITH 100% ACCURATE SOLUTIONS

Histones are rich in what AAs? - ANSWER ☑☑Lysine and arginine (both + charge) When does histone synthesis occur? - ANSWER ☑☑S phase (along with DNA getting synthesized) Heterochromatin is _________, euchromatin is _________ - ANSWER ☑☑Inactive/condensed; active/accessible What allows mismatch repair enzymes to distinguish between old and new DNA strands in prokaryotes? - ANSWER ☑☑Methylation; old/template strands are methylated, new/daughter strands are unmethylated (and might have errors) Methylated histones are _________ while acetylated histones are __________ - ANSWER ☑☑Inactive "Mute"; active How do you tell thymine and cytosine apart? - ANSWER ☑☑THYmine has a meTHYl group Which is stronger, CG or AT bonds? - ANSWER ☑☑CG (three H bonds instead of 2); higher GC content leads to higher melting temp of DNA Amino acids necessary for purine base synthesis - ANSWER ☑☑"GAG" = Glycine, Aspartate, Glutamine Nucleoside - ANSWER ☑☑Base + sugar (nucleoSide = Sugar) Nucleotide - ANSWER ☑☑Base + sugar + phosphate (nucleoTide = phosphaTe)