unit 1 KA2 - replication of DNA Flashcards
what is required to start DNA replication
DNA polymerase
when is DNA replicated and what does it
prior to cell division, DNA polymerase
what does DNA polymerase require to start replication
primers
what are primers
a primer is a short strand of nucleotides which binds to the 3’ prime end of the template DNA strand allowing polymerase to add DNA nucleotides
what enzyme is used to join fragments of DNA together
ligase
describe the steps to DNA replication
- prior to cell division, DNA is replicated by a DNA polymerase
- DNA polymerase needs primers to start replication
- a primer is a short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides
- DNA is unwound and hydrogen bonds between bases are broken to form two template strands. DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and the lagging strand replicated in fragments
what direction does DNA polymerase add DNA nucleotides onto the leading strand
5’ to 3’
what does DNA polymerase use to add nucleotides to the strands
complementary base pairing
what is the polymerase chain reaction
a process which 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 region of DNA to be amplified
what are the repeated cycles of heating and cooling in PCR. name the temperate and what happens at each stage
- 1) DNA heated to between 92-98 degrees to separate the strands.
- 2) it is then cooled to between 50 and 65 degrees to allow primers to bind to the target sequences
- 3) it is then heated to between 70 an 80 degrees for heat-tolerant DNA polymerase to replicate the region of DNA
what are the practical applications of PCR
- solve crimes
- settle paternity suits
- diagnose genetic disorders
what does PCR stand for
polymerase chain reaction
