DNA replication: Repair Flashcards
A large protein complex forms at the origin of replication. One of the these initiator proteins is the product of what gene?
adnA gene
How many replication units are present in genomes?
20-80
What is an ARS?
Autonomous Replicating Sequence. Contains all elements necessary for replication. It includes the sequence required to bind the origin recognition complex
What is the ORC?
Origin recognition complex. Binds to chromosome most of the cell cycle
After the telomerase adds extra nucleotides to the end of the strand, what polymerase synthesizes the strand?
alpha
Define Depurination
Cleavage of the bond between the purines and the sugar
Define deamination
Loss of an amine turns a cytosine into uracil
What is thymine dimers?
A mutation where two adjacent thymines stick together. Caused by the sun
what enzyme excises misplaced base
specific base glycosylase
What excises the sugar-phosphate backbone of a misplaced nucleotides
endonuclease and phosphodiesterase
Define base excision repair
One misplaced nucleotide is excised and replaced by DNA polymerase, followed by ligation
Define nonhomologous end joining
When dsDNA is broken, its joined back together, with the loss of several nucleotides
Define homologous recombination
Use of sister chromatid as template to repair missing section caused by break
What is the importance of the H2AX histone variant
Is able to quickly spread across DNA after a break has occurred, attracting repair machinery and slowing transcription of genes.
What are the two types of double stranded break repair?
non-homologous end joining and homologous recombination
