Unit 1 (K2) - Replication/PCR Flashcards
What can the structure of DNA be described as?
A double helix
What do nucleotides consist of?
A deoxyribose sugar, a phosphate and a nitrogenous base.
What are the complimentary base pairs?
Adenine to Thymine, and Guanine to Cytosine.
What can be found at the 5’ end of a nucleotide?
A phosphate
What can be found at the 3’ end of a nucleotide?
A deoxyribose sugar.
What does antiparallel mean?
This is where one strand runs from 5’ to 3’ and the other 3’ to 5’.
How are bases on opposing strands connected?
Weak hydrogen bonds.
How are nucleotides on the same strand joined?
Peptide bonds.
What controls DNA replication?
DNA polymerase.
What does DNA polymerase need to start replication?
Primers
What are primers?
A short strand of nucleotides which bind to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides.
Where does DNA polymerase attach nucleotides?
To the 3’ end of the DNA strand.
What strand is replicated continuously?
The leading 3’ strand.
What strand is replicated in fragments (discontinuously)?
The lagging 5’ strand.
What enzyme joins the DNA fragments on the lagging strand?
Ligase.
In addition to enzymes and primers, what does DNA replication require?
ATP and free nucleotides.
What is a cellular process for which DNA replication is essential?
Mitosis/meiosis
What happens during stage 1 of PCR?
DNA is heated to between 92 to 98 degrees. This denatures DNA causing the strands to separate.
What happens during stage 2 of PCR?
Temperature is reduced to 55 degrees to allow primers to bind to target sequences.
What happens during stage 3 of PCR?
Temperature is increased to 72 degrees to allow heat tolerant DNA polymerase to replicate region of DNA (synthesise new DNA molecules).
What is the function of PCR?
To amplify DNA
What are the amplifications of PCR?
Solve crimes using DNA profiling, disease detection (genetic disorders), and for paternity testing.
Why is temperature increased during stage 3?
To allow heat-tolerant DNA polymerase to add complimentary DNA nucleotides and therefore replicate the DNA.
