the replication of DNA Flashcards
What happens prior to cell division?
DNA is replicated by DNA polymerase
What does DNA polymerase need?
PRIMERS to start replication
What is a primer?
It gives DNA polymerase a starting point for replication.
It is short strand of nucleotide that binds to the 3’ end of the template DNA strand.
This allows DNA polymerase to add DNA nucleotides
What is the first step of DNA replication?
DNA unwinds and hydrogen bonds between the complimentary bases break to form 2 template strands.
What is the second step of DNA replication?
A primer attaches to the 3’ end of the template strand to provide a starting point for replication
What is the 3rd step of DNA replication?
DNA polymerase adds free DNA nucleotides complementary to the template strand, to the deoxyribose (3’) of the new strand forming
What is the 4th step of DNA replication?
DNA polymerase can only add nucleotides in one direction from 5’ to 3’ on the new strand, so the LEADING strand is replicated CONTINUOUSLY and the lagging strand is replicated in FRAGMENTS
What is the 5th step of DNA replication?
Fragments on the lagging strand are joined together by the enzyme LIGASE
How does PCR amplify DNA?
PCR AMPLIFIES DNA using complimentary primers for specific target sequences.
What are primers in PCR?
In PCR, primers are short strands of nucleotides.
They are complimentary to specific target sequences at the 2 ends of the region of DNA to be amplified.
What is PCR?
Repeated cycles of HEATING & COOLING amplify the target region of DNA.
What is the first step of PCR?
DNA is heated to between 92 and 98C to separate the strands.
What is the 2nd step of PCR
It is then cooled to between 50 and 65c to allow Primers to bind to target sequences
What is the 3rd step of PCR?
It is then heated to between 70 and 80c for HEAT-TOLERANT DNA Polymerase to replicate the region of DNA.
What is the 4th step of PCR?
The cycle is then repeated.
Each cycle DOUBLES the amount of DNA present.
