MCAT Biology Exam Guide with Latest Update

Central Dogma - Answer-DNA → RNA → Protein Purines - which bases? - how many rings? - Answer- Pyrimidines - which bases? - how many rings? - Answer-Remember: "Pyrimidine" has a "y" in it; so does "cytosine" and "thymine." Phosphodiester Bond - 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) - Answer-5' → 3' (but strands are antiparallel, so other strand is opposite) 3' of DNA attached to ... - Answer-OH 5' of DNA attached to ... - Answer-Phosphate group DNA composition - Answer-1. Phosphate group 2. 5-Carbon sugar 3. Nitrogenous base (A, T, G, C) Which nitrogenous bases form 2 hydrogen bonds? - Answer-A, T Which nitrogenous bases form 3 hydrogen bonds? - Answer-G, C Replisome - Answer-Proteins that govern the replication process Origin of replication - Answer-Where replication begins. Prokaryotes have 1; eukaryotes have many on each chromosome DNA synthesis: direction of synthesis - Answer-5' → 3' (the DNA is read 3' → 5') Steps of replication (5) - Answer-1. Helicase unzips double helix 2. RNA polymerase builds a primer 3. DNA polymerase adds leading/lagging strands 4. Primers removed