LIFESCI 3 Chapter Notes - Chapter 11.2: Tautomer, Exonuclease, Okazaki Fragments
Document Summary
Dna polymerases elongate dna in the 5" 3" direction. A template strand that guides the polymerization reaction. A primer strand that is complementary to the template and contains a free 3"-oh group to which a nucleotide can be added. Dna polymerases can only add nucleotides to a preexisting strand. Can"t synthesize dna starting from only a template strand. Primer terminus: 3" end of primer where nucleotides are added. Primed template: double stranded rna-dna formed by primer and template. Nucleotide precursors to dna are the four dntps (deoxyribonucleoside 5"- triphosphates) Different dntps bind the same active sites on pol i. Pol i differentiates among dntps after undergoing a conformational change that checks for proper geometry of the base pair formed with the matching base on template strand. Incorrect fit results in dissociation of dntp and binding of new one. One in every 104 to 105 nucleotides are added incorrectly.
