Ka 2 Flashcards
Name 2 molecules needed to replicate DNA
Primers
DNA polymerase
Name the molecule needed before DNA polymerase can start replication
Primer
Describe the structure of a primer
Short strand of nucleotides
Which end does a primer bind to
3’ end
Explain why a primer binds to the 3’ end
This allows DNA polymerase to add DNA nucleotides
Describe the role of DNA polymerase in DNA replication
DNA polymerase adds nucleotides using complementary base pairing to the deoxyribose 3’ end of the new dna strand which is forming
Describe how dna is replicated in the leading strand
DNA is unwound and hydrogen bonds between the bases are broken to form 2 template strands
DNA polymerase can only add nucleotides in one direction resulting in the leading strand behind replicated continuously
State the function of PCR
To amplify DNA
Describe the role of primers in pcr
Primers are short strands of nucleotides which are complementary to specific target sequences at the two ends of the region of dna to be amplified
Describe how dna is replicated in the lagging strand
DNA is unwound and hydrogen bonds between the bases are broken to form 2 template strands
Dna polymerase can only add dna nucleotides in one direction creating fragments
Fragments of dna are then joined together by ligase
Describe the process of pcr
DNA is heated between 92°c and 98°c to separate the strands
Then cooled between 50°c and 60°c to allow primers to bind to target sequences
then heated again between 70°c and 80°c for heat tolerant polymerase to teplicse the region of dna
state the functions of PCR
help solve crime
settle paternity suits
diagnose genetic disorders
suggest why ligase is not needed in PCR
as only fragments of dna are replicated they do not need to be joined together
