USMLE STEP 1 BIOCHEMISTRY EXAM 2024 WITH 100% CORRECT ANSWERS

What changes a cytosine into a uracil? Which base nucleotides contain an extra amino group? Which base nucleotide has an extra methyl group? What are the purines?Pyrimidines? How does Methyltrexate work on DNA? If a sample of DNA has 10% G, how much is the T %? Which DNA has a higher melting point?Why?Define melting point. What is the charge of Histones?What 2 AA are histones abundant in? what causes chromatin to be tightly packaged?Name of this type of chromatin? (active or inactive)If it is not packed tightly, what is it sensitive to? Endonuclease activation and chromatin fragmentation are characteristic of cell death by apoptosis. What nucleic cell structure would most likely be degraded first in an apoptotic cell? number of origins the prokaryote and eukaryote can begin with regarding DNA replication? What is the same structure in DNA and RNA synthesis?