DNA Replication Flashcards
What bonds are broken during DNA replication?
H Bonds
Where does DNA replication begin?
Origin of Replication (ORI)
How many ORI’s are in a bacterial genome?
One
TRUE OR FALSE:
Eukarotic genomes have many ORI’s
TRUE
What 2 bases are most prevalent in the ORI?
A and T
What is the difference between a bacterial genome and a eukaryotic genome?
- Bacterial genome is CIRCULAR
- Eukaryote genome is LINEAR
DNA replication is:
A) Unidirectional
or
B) Bidirectional
B) Bidirectional
Which end of a DNA strand are new nucleotides added to?
3’ end
What does the new nucleotide add onto the 3’ end of the primer strand as?
Deoxyribonucleoside Triphosphate
What does DNA polymerase require in order to work?
- Template
- Primer
What can RNA polymerase do the DNA polymerase cannot?
Start an RNA chain from scratch
What are the functions of DNA polymerase 1?
- Polymerase (adding onto template strand)
- 5’ exonuclease (correcting mistakes from 5’ to 3’)
- 3’ exonuclease (correcting mistakes from 3’ to 5’)
What are the functions of DNA Polymerase 3?
- 3’ exonuclease
- Polymerase
What are the three stages of DNA replication?
- Initiation
- Elongation
- Termination
What happens at the Initiation stage of DNA replication?
- Starts at ORI
- Helicase unwinds helix in both directions
- Creates 2 replication forks
- Single stranded binding protein (SSB) prevents reassociation between unwound DNA strands
What enzyme produces the primer for DNA polymerase?
Primase
What is the enzyme that links DNA strands together?
DNA Ligase
What happens at the Elongation stage of DNA replication?
Synthesis occurs in a 5’ to 3’ directions on BOTH STRANDS
On which DNA strand is synthesis happening continuously?
The Leading Strand
On which DNA strand is synthesis happening discontinuously?
The Lagging Strand
Which is the major DNA replication enzyme?
DNA Polymerase III
How does DNA synthesis happen on the LEADING STRAND?
- RNA primer is synthesised
- DNA Pol III adds DNA nucleotides to new strand
- DNA Pol I removes RNA primer and fills in the gap (5’ to 3’)
- DNA ligase links new DNA strands (phosphodiester bond)
How does DNA synthesis happen on the LAGGING STRAND?
- Made up of Okazaki Fragments each with its own primer
- DNA Pol III extends the primer from the 3’ end
- DNA Pol III stops at next RNA primer
- DNA Pol I removes RNA primer and fills in gap
- DNA ligase links the two new DNA strands (phosphodiester bond between 3’ OH and 5’ phosphate)
