genetic engineering

Question 1

how is the required gene obtained in genetic cloning

Answer 1

-mRNA can be obtained from cell where the gene is expressed
-reverse transcriptase can then catalyse the formation of complementary DNA strand. then, double strand can be made with RNA polymerase and primers. base sequence codes for original protein
-if scientists know sequence of gene, they can design PCR to amplify the gene
-use a DNA probe to locate a gene, then cut out with restriction enzymes

Question 2

how is the gene placed in a vector

Answer 2

-plasmids are mixed with restriction enzymes which cut the plasmid at specific recognition sites
-this exposes unpaired nucleotide bases, called sticky ends
-complementary nucleotides added to a gene, so will anneal to cut plasmid with DNA ligase

Question 3

ways of getting the vetcor into the recipient cell

Answer 3

-heat shock treatment
-electroporation
-electrofusion
-transfection

Question 4

what is electroporation

Answer 4

a high voltage pulse applied to cell to disrupt membrane

Question 5

what is electrofusion

Answer 5

electrical field to introduce DNA into cells. tiny currents applied to membranes of two cells. membranes fuse.

Question 6

what is transfection

Answer 6

DNA can be packaged into bacteriophage, the transferred into host cell

Question 7

what is the direct method of introducing gene into recipient

Answer 7

small pieces of gold or tungsten are coated with DNA and shot into the plant cell. called ‘gene gun’

Question 8

what does ligase enzymes do

Answer 8

catalyse condensation reactions that join DNA