DNA Replication And Repair Flashcards
What direction does DNA replication proceed?
5’ to 3’ direction
DNA is replicated in one smooth, continuous process
DNA is replicated in small sections then fused together
Short section of RNA which is complementary to the template strand and contains free 3’ OH group
Separates the DNA strands. Requires ATP.
What reaction does DNA polymerase catalyze?
Hydrolysis of PPi to 2Pi that allows the incoming nucleotide to be bound to the strand.
RNA polymerase that is required to initiate DNA synthsis
Short sections of primer RNA plus DNA that form on the lagging strand. Will be joined together later.
Total proteins and enzymes required for DNA synthesis at a replication fork
Acts to prevent the extreme supercoiling of the parental helix by breaking and rejoining DNA chains. Relieves the tension ahead of the replication fork.
Type I topoisomerase
Makes a break/nick in a strand of DNA helix, passes the other strand thru the break to relax the coil. Removes 1 supercoil
Type II topoisomerases
Requires ATP. AKA DNA gyrase in E. Coli Produce break in BOTH strands of DNA. 2 supercoils are removed in one step
Single Stranded binding protein
Keeps the separated strands as single strands. Are displaced and reused as DNA is replicated
DNA polymerase I
Removes RNA primers (5’ –> 3’ exonuclease activity) and fills in gaps with dNTP that matches the exposed DNA template. Edits/proofreads the strand (3’->5’ exonuclease activity), cleaving off any unpaired 3’ terminal nucleotide
DNA polymerase III
Major replicative enzyme. Stays on the DNA molecule for long stretches of processing
Enzyme that catalyzes formation of phosphodiester bond b/t 2 Okazaki fragments
Types of DNA mutations
Point mutations, insertions, deletions
substitution of one base for another