Replication of DNA Flashcards
What is DNA replication?
Process where DNA makes an identical copy of itself and 2 doubles helices are produced.
What are the requirements for DNA replication?
DNA template
Enzymes (DNA polymerase)
ATP
DNA nucleotides
Primers
What does DNA polymerase require to start replication?
Primers
What are primers?
A short strand of nucleotides which binds to the 3’ end of the template DNA strand.
What is the first stage of DNA replication?
DNA is unwound by an enzyme.
What is the second stage of DNA replication?
Hydrogen bonds break between bases (unzip) to form two template DNA strands.
What is the third stage of DNA replication?
On the leading strand the primer binds at the 3’ end of the template strand.
On the lagging strand primers bind at several sites at the 3’ end.
What is the fourth stage of DNA replication?
DNA polymerase can add nucleotides in one direction (3’ to 5’).
This means DNA polymerase will add complimentary DNA nucleotides to the 3’ end of the leading strand continuously and the in fragments along the lagging strand.
What is the fifth stage of DNA replication?
The fragments of DNA on the lagging strand are joined together by the enzyme ligase.
What is PCR?
Polymerase chain reaction.
This amplifies DNA using complementary primers for specific target sequences.
What are primers in PCR?
Short strands of nucleotides which are complementary to specific target sequences at the two ends of the DNA to be amplified.
What are some practical applications of PCR?
Can amplify DNA to:
- Help solve crimes
- Settle paternity suits
- Diagnose genetic disorders
What is the first stage of PCR?
DNA is heated to between 92 and 98°C to separate the DNA strands.
What is the second stage of PCR?
DNA is then cooled to between 50 and 65°C to allow primers to bind to target sequences.
What is the third stage of PCR?
DNA is then heated to between 70 and 80°C for heat-tolerant DNA polymerase to replicate the region of DNA.
