21.3 in vitro gene cloning - the polymerase chain reaction

Question 1

polymerase chain reaction

Answer 1

method of copying fragments of DNA
- automated making it rapid and effective

Question 2

what does the PCR need

Answer 2

1. DNA fragments to be copied
2. DNA polymerase (joins together nucleotides)
   - obtained from hot springs so is thermostable
   3, primers
   - short sequence of nucleotides that have bases complementary to the end of the DNA fragments
   - 10 -20 babes long
3. nucleotides
   - contain each of the 4 bases found in DNA
4. thermocycler
   - machine that varies temperature precisely

Question 3

PRC process

Answer 3

1. separation of the DNA strand
   - DNA fragments, primers and DNA polymerase placed in the thermocycler
   - temperature increased to 95 C - two strands of the DNA fragments to separate due to the breaking of the hydrogen bonds
2. Annealing of the primers
   - mixture cooled to 55 C
   - caused the primers to anneal to their complementary bases at the end of the DNA fragments
   - Primers signal DNA polymerase to begin DNA copying and prevent the strands from rejoining
3. synthesis of DNA
   - temperature is increased to 72 C
   - DNA polymerase adds complementary nucleotide along each of the separated DNA strands

Question 4

advantages of in vitro gene cloning

Answer 4

1. extremely rapid
2. does not require living cells