Chapter 11 Flashcards
What is dna replication
Process that copies genetic material
What are original dna strands used for
Templates when synthesizing new strands with identical sequences
What does dna replication rely on
Complementarity of dna strands
The A T and G C rule
What are the old and new strands of dna called
New strands are daughter strands
Old strands are parental strands
What is bacterial dna replication
Formation of two replication forks at the origin of replication
Where does dna synthesis begin
Origin of replication
Each bacterial chromosome only has one
Which way can bacterial dna synthesize dna
Bidirectionally
What are the three types of dna sequences in the oriC
DnaA boxes which are the sites for binding DnaA protein
AT rich regions which are the sites where dna strands separate
GATC methylation sites which help regulate dna replication
After the DnaA proteins bind to the DnaA boxes and the strands separate at the AT rich region what does the DnaB or helix see do
Binds to the origin and further separates the DNA strands
It travels along the DNA in 5-3 prime direction and uses energy from ATP
Made of six subunits
Is the daughter strand methylated directly after replication
No the DNA adenine methyltransferase methylates it
Initiation of replication occurs only after the dna is fully methylated
What enzyme separates the two dna strands and how
DNA helicase by breaking hydrogen bonds
This creates positive supercoiling ahead of the replication fork
What does topoisomerase or dna gyrase do
Travels ahead of the helicase and gets rid of the supercoils
What is a single strand binding protein
Binds to separated dna strands to keep them apart
What are rna primers synthesized by
Primase
What is dna polymerase
Enzymes responsible for synthesizing dna
What does dna polymerase III do
Synthesize a daughter strand of dna
What does dna polymerase I
Removes rna primers and fills the gaps with base pairs
What does dna ligase do
Links the dna backbones in the Okazaki fragments together
What does dna polymerase I and III do versus dna polymerase II,IV, and V
I and III do normal replication
II, IV, and V repair and replicate damaged dna
What are some features of dna polymerase
It cannot initiate dna synthesis by linking nucleotides
It needs a 3’ hydroxyl group and always adds to the 3’ end
What is the leading strand
RNA primer made at the origin
DNA pol III adds nucleotides as it slides toward the replication fork
What is the lagging strand
Synthesized in the 5-3 prime direction but occurs away from the replication fork
Many rna primers are required
Looped
What are Okazaki fragments
Chunks of Complementary strands of dna on the lagging strand
Made by dna polymerase III
What makes up a primosome
DNA helicase and primase binding to each other
How is a replisome formed
Primosome associated with two dna polymerase holoenzymes
What are the two important ter sequences
T1 which stops counterclockwise forks
T2 which stops clockwise forks
When tus binds to ter sequences what happens
They stop the movement of the replication forks
What are catenanes
Intertwines circular molecules
Separated by the action of topoisomerase II
What does dna polymerase form bonds between
Innermost phosphate group of incoming deoxyribonucleoside triphosphate and the 3’ OH of the sugar of the previous deoxynucleotide
