topic 7 modern genetics

Question 1

what is PCR (polymerase chain reaction)

Answer 1

a technique which amplifies DNA and makes millions of copies of specific regions in a very short amount of time.

we say DNA is amplified when it is repeatedly replicated using PCR to produce a much larger sample

Question 2

explain the principles of PCR

Answer 2

1) setting up the reaction mixture contains of the primers (small sequences of DNA whuch must join the beginning of the seperated strands before copying can happen), the DNA sample to be amplified, free nucleotides and the DNA polymerase enzyme and the enzyme TAQ
2) the sample is heated to 95 degrees to cause DNA strands to break as hydrogen bonds are broke and cooled to 55 degrees to facilitate the binding of DNA primers with the DNA strand
3) the temp is set to 72 degrees for DNA polymerase + TAQ to work
4) DNA polymerase makes strands of new DNA by complement strand synthesis
5) each cycle doubles the amount of DNA present in the sample, this process then repeats

Question 3

what is the genome

Answer 3

the total of all the genetic material within a organism, the DNA that makes up human chromosomes consists of millions of base pairs however only 2% is coding (exons) and the large non coding section is known as introns

Question 4

explain the breakthrough of using the enzyme from bacteria Thermus aquaticus

Answer 4

• issue when scientists needed to heat the reaction to around 95-90 degrees as this destroyed DNA polymerase in most organisms
• Thermus aquaticus bacteria lived in hot springs, the enzymes were evolved to live in these conditions, so is used and joined with DNA polymerase