Replication of DNA Flashcards
What is DNA replicated by?
DNA Polymerase
What does DNA Polymerase need to start replication?
Primers
What is a primer?
A primer is a short strand of nucleotides that binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides.
How does DNA polymerase replicate DNA?
It adds DNA nucleotides, using complementary base pairing, to the deoxyribose (3’) end of the new DNA strand that is forming.
What is the first step in DNA replication?
DNA is unwound and hydrogen bonds between bases are broken to form two template strands.
Explain the leading strand and lagging strand.
As DNA polymerase can only add DNA nucleotides in one direction, the leading strand is continuously replicated but the lagging strand has to be replicated in fragments.
What joins the fragments of DNA together?
A protein called ligase.
What does PCR do?
Polymerase chain reaction amplifies DNA using complementary primers for specific target sequences/
What are primers in PCR?
Primers are short strands of nucleotides complementary to specific target sequences at the two ends of the region of DNA to be amplified.
What amplifies the target region of DNA?
Repeated cycles of heating and cooling.
Name and describe the three steps in heating and cooling the target region.
- DNA is heated to between 92-98 celsius to separate the strands.
- It is then cooled to between 50-65 celsius to allow primers to bind to target sequences.
- It is then heated to between 70-80 celsius for heat-tolerant DNA polymerase to replicate the region of DNA.
What are the practical applications of PCR?
Helping to solve crimes, settle paternity suits and diagnose genetic disorders.
