U1.2 Replication of DNA Flashcards
How is DNA replicated?
Semi-conservatively.
What enzyme is required for DNA replication?
Original DNA template, free DNA nucleotides, DNA polymerase, primers.
What are primers?
Short strands of nucleotides.
What does the enzyme helicase do?
Unwinds the DNA double helix and the hydrogen bonds between complementary bases are broken.
What is required for DNA polymerase to start replication?
A primer must bind to the 3’ end of the single-stranded template of DNA, allowing polymerase to add DNA nucleotides.
In what way must DNA polymerase add DNA nucleotides to the new DNA strand?
To the 3’ (deoxyribose) end, i.e it only works in one direction.
Compare the replication of the leading versus the lagging strand of DNA.
The leading strand is replicated continuously whilst the lagging strand is replicated in Okazaki fragments.
What does the enzyme ligase do?
Joins DNA nucleotides together.
What does PCR do?
Amplifies short sections of DNA using primers for specific target sequences.
What are primers, in terms of 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 is required for PCR?
Primers.
Describe the PCR cycle.
DNA is heated to between 92 and 98°C to
separate the strands.
It is then cooled to between 50 and 65°C to allow primers to bind to target sequences.
It is then heated to between 70 and 80°C for heat-tolerant DNA (Taq) polymerase to replicate the region of DNA.
What are some uses of PCR?
Amplifies DNA samples to help solve crimes, settle paternity suits and diagnose genetic disorders.
