Unit 1 Topic 6
Genetic Engineering
Pupil Notes
Transfer of genetic information
Genetic information can be transferred from one cell to another naturally or by genetic engineering.
Natural transfer of genetic information
Genes can be transferred naturally between cells, for example bacteria contain circles of
DNA called plasmids. These and the genes they contain can be passed from one bacterial cell
to another (the cell receiving the plasmid may be a totally different type of bacterium from
the one donating it).
Gene transfer of this kind can result in antibiotic resistance in one species of bacteria being
transferred to another species of bacteria.
Viruses can also transfer genes between bacterial cells.
Genetic information can also be transferred artificially between cells by genetic engineering.
Artificial transfer of genetic information by genetic engineering.
Any organism produced by genetic engineering processes can be called a genetically
modified (GM) organism, or GMO.
In genetic engineering, a piece of chromosome containing a desired gene from the cell of one
organism (e.g. a human) can be transferred into a bacterial cell. The bacterial cell may then
produce a substance normally made by the other organism.
Genetic engineering is of medical value because useful substances which can be produced
include: human insulin used by people suffering from diabetes to control their blood sugar
levels, and human growth hormone.
Stages in genetic engineering
plasmid
1. Gene to be
chromosome
transferred is
identified and cut
from the
chromosome using
an enzyme
bacterial cell containing plasmid
Plasmid removed from
cell
2. Gene is joined
to the plasmid
using an enzyme
Plasmid cut open using
an enzyme
3. Plasmid containing the
transferred gene is placed
into a bacterial cell
4. “Host” bacterial cell and the
plasmid it contains reproduce
to make more copies of the
transferred gene
5. Protein made by the gene, e.g. insulin, is
extracted and purified
Human insulin was first produced by this method in 1982.
Advantages of genetic engineering include, given suitable conditions, the bacteria used for
genetic engineering can be grown quickly, the product can be produced relatively cheaply
and large quantities of product can be manufactured.