MCAT Biology questions with answers

MCAT BiologyCentral Dogma - correct answer DNA → RNA → Protein Purines - which bases? - how many rings? - correct answer Pyrimidines - which bases? - how many rings? - correct answer Remember: "Pyrimidine" has a "y" in it; so does "cytosine" and "thymine." Phosphodiester Bond - correct answer Joins one nucleotide to the next; between the 3rd C of one ribose and the 5th C of the other to create the sugar-phosphate backbone Directionality of DNA (convention) - correct answer 5' → 3' (but strands are antiparallel, so other strand is opposite) 3' of DNA attached to ... - correct answer OH 5' of DNA attached to ... - correct answer Phosphate group DNA composition - correct answer 1. Phosphate group 2. 5-Carbon sugar 3. Nitrogenous base (A, T, G, C) Which nitrogenous bases form 2 hydrogen bonds? - correct answer A, T