Medical applications of GM technology products - gene therapy
- gene editing
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of biology notes on genetics and applications of GM biotechnology from
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Medical applications of GM technology products including
genetic modifications to the human genome
(a) The production of human insulin by
genetically modified bacteria (discussed in detail
in Part 2).
GM produced insulin production has
been described in detail above.
The process overall is one of inserting the
human insulin gene into bacteria and growing the bacteria to produce lots of
insulin quickly and economically efficiently (cheaply!).
The resulting, and efficiently produced, insulin can be used to treat people with
diabetes, and is an example of genetically engineering bacteria, in this
case to produce human insulin.
other medical applications, scientists have
transferred human genes into cows and sheep to produce useful proteins.
You can 'manufacture' human antibodies used in
the treatment of arthritis, multiple sclerosis and some types of cancer.
These useful proteins can be extracted from the
'host' animal e.g. from cows milk.
It might be possible in future to use animal
organs grown specially for transplant operations - ethical issues!
(c) Medical researchers are trying to develop
genetic modification treatments for inherited diseases caused by faulty
The idea is to insert correctly working genes
(the normal correctly working allele)
into the cells of people suffering from the disorder caused by
alleles of faulty genes.
This technique is called gene therapy - a
sort of allele replacement technique.
Gene therapy is at a very experimental stage,
but much is hoped from this technique.
It is sometimes possible to transfer the
'working' gene when the organism is at an early stage of development.
However, the following description describes one
particular type of gene therapy involving cell exchange.
example of a gene therapy procedure
A deactivated virus is used as a vector, but it
is quite difficult to replace genes effectively.
(1) A normal human allele is inserted into the
virus vector - the altered virus.
(2) Cells carrying the defective gene are removed
from the patient.
(3) The altered virus is inserted into the cells
removed from the patient.
(4) The modified cells are then injected back
into the patient.
(5) Then, hopefully, the modified cells can then
carry out their function correctly.
Problems encountered in gene therapy patients
An overactive immune response, which in some
early cases was lethal - the modified cells were treated as foreign
pathogens by the immune system.
Leukaemia cases occurred, probably due to the
Genome editing is emerging as a potential
biotechnology involving replacing or removing sections of DNA of an
It is possible to do this using 'molecular
scissors' and the technique is improving all the time.
(As I'm writing this in 2020, two female
scientists have been awarded the Nobel Prize in Chemistry for their work
in developing gene editing techniques. Emmanuelle Charpentier and
Jennifer A. Doudna developed the Crispr tool, which can change the DNA
of animals, plants and microorganisms with high precision.)
Note that any successful gene therapy cannot
prevent the patient from passing on an inherited medical condition to
It is only the patient's cells that are modified.
Any modification of the reproductive cells (male
and female gametes) involves at least two immediate problems.
(i) Extremely technically difficult to do,
(ii) and poses major ethical problems as to the
right to carry out such a procedure - 'designer babies'.
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