Genetically modifying Bacteria

Question 1

How does gene therapy work?

Answer 1

1 The ends of the desired gene are cut using a restriction enzyme which breaks the DNA at specific base sequences to leave complementary
‘sticky ends’ on the gene. The plasmid is also cut open using the same restriction enzyme.
DN
are both res
The plasmid may be labelled by having marker genes (e.g., antibiotic resistance genes, an enzyme gene, or fluorescence genes) inserted into it so that it can be detected after modification.
2 Ligase enzymes ‘glue’ the sticky ends of
sticky
DNA
the plasmid and the gene together with a phosphodiester bond to seal the sugar phosphate backbone, thus forming recombinant DNA.
3 Large quantities of the plasmid are incubated with the host bacteria to ensure the bacteria take up some of the recombinant DNA.

Question 2

What is Electroporation used for?

Answer 2

Electroporation (an electric shock) may be used to increase cell membrane permeability to plasmid uptake.