DNA Replication and Sequencing Flashcards
What is the key enzyme for DNA replication?
DNA polymerase
What is the template for DNA replication?
The parent strand of DNA
What are the subunits used for DNA replication?
dNTPs
Where does DNA replication begin?
Origin of replication - ori
What type of bond links two nucleotides together?
A phosphodiester linkage between the 3’ OH of the previous nucleotide and the 5’ phosphate of the next nucleotide
What provides the energy to link two nucleotides together?
Cleavage of two of the phosphates of the dNTP
What are the 3 steps of DNA replication?
- Helicase unwinds the DNA
- Primase creates a short RNA primer
- DNA polymerase synthesizes the new strand in the 5’ to 3’ direction
What is PCR used for?
To amplify a sequence of DNA of interest in vitro
What 4 things are required for PCR?
- Template DNA of the sequence of interest
- Sequence specific primers, forward and reverse
- dNTPs
- DNA polymerase
What are the 3 steps that are repeated in PCR?
- Denaturation. The two strands of DNA are separated by heat breaking the hydrogen bonds
- Primer hybridization. Cooled to allow the primers to anneal to their complementary sequences
- Extension. The temperature is increased to the optimal temperature of the Taq DNA polymerase and it synthesizes new DNA off the primer
What can PCR tell us?
- The size of the DNA fragment between the primers
2. If the sequence of interest is present
What can’t be determined by PCR?
The sequence of DNA that was amplified between the primers
What is Sanger sequencing?
A method to determine the order of nucleotides by chain termination
How does chain termination occur with Sanger sequencing?
Dideoxynucleotides. There is no 3’ OH for DNA polymerase to extend off, so the chain gets terminated
What are the 5 components in a Sanger sequencing reaction?
- Template DNA
- dNTPs
- DNA polymerase
- Labelled primers
- One of 4 ddNTPs in small amounts