1.2 DNA Replication and PCR Flashcards
How is DNA replicated?
By DNA polymerase and primers. DNA polymerase needs primers to start replication
When does DNA replication happen?
Prior to cell division
What is a primer?
A short strand of nucleotides which binds to the 3’ end of the template DNA strand, allowing polymerase to add DNA nucleotides
How does DNA polymerase add DNA nucleotides?
By using complementary base pairing, to the deoxyribose 3’ end of the new DNA strand which is forming
How are the template strands formed?
DNA is unwound and hydrogen bonds between the bases are broken to form 2 template strands
What does DNA polymerase only adding nucleotides in one direction mean?
The leading strand is replicated continuously and the lagging strand is replicated in fragments
How are fragments of DNA joined?
The enzyme ligase
What does PCR stand for?
Polymerase chain reaction
What does PCR do?
Amplifies DNA using complementary primers for specific target sequences
What is a primer (in PCR)?
A short strand of nucleotides which are complementary to specific target sequences at the two ends of the region of DNA to be amplified
What are the three stages of PCR?
Denaturing, Annealing, Extension
What happens in denaturing?
DNA is heated between 92-98°C to separate the strands
What happens in annealing?
It is cooled to 50-65°C to allow primers to bind to target sequences
What happens in extension?
It is heated to between 70-80°C for heat-tolerant DNA polymerase to replicate the region of DNA
What are the practical applications of PCR?
It can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders
