Lecture 5 Flashcards
transforming principle
Transformation occurs when one bacterium picks up free-floating DNA and incorporates it into its own genome– the principle was that something caused the bacteria to transform from one type to another
Briefly describe the methods of Avery’s experiments (DNA as Molecule of Heredity)
added protease, RNAse, and DNAse to 3 different flasks with bacteria, transformation occurred in the protease and RNAse treatments but no transformation in the DNAse flask
What is the ultimate purpose of DNA?
Information storage and transfer
DNA polymerase can only add to the _____.
3’ end– must have a preexisting -OH gropu to add to
major groove vs. minor groove
major groove is where the backbones are far apart, minor groove where they are close together
Which direction does proofreading occur in?
3’-5’ by DNA Pol I
endonuclease
cleaves the phosphodiester bonds in the middle of the DNA strand– large component of restriction enzymes and recombinant DNA technology
exonuclease
hydrolyze phosphodiester bonds at the 3’ or 5’ end of the DNA
lagging vs. leading strand
lagging strand is constantly falling off, synthesizing, falling off, synthesizing– leading strand synthesizes continuously
At every origin there are ______.
2 replication forks– creates a bubble and forks grow in both directions
(only one origin in bacteria because they are circular)
helicase
enzyme that unzips DNA helix
primase
synthesizes an RNA primer to be used for DNA synthesis (one primer for leading strand, one per every Okazaki fragment for lagging)
DNA Polymerase III
Adds bases to new DNA chain, proofreads for mistakes
DNA Polymerase I
Removes RNA primers, replaces gaps with Okazaki fragments with the correct nucleotides, repairs mismatched bases
ligase
final binding of nicks in DNA during synthesis and repair
