Gene technology
Task 1 – Genetic engineering of human insulin
The process of genetic engineering involves taking a gene from one organism and inserting it
into another. The activity below is a cut and stick task showing how an insulin gene from a
human cell is removed and inserted into bacteria which will produce the insulin for us.
DNA plasmid is cut with
Bacteria multiply by
same enzyme
mitosis
Insulin gene is
Insulin gene is cut out
inserted into plasmid
of the human DNA
by a second enzyme
using an enzyme
Bacterial cell
Human cell containing
containing DNA
insulin gene
plasmid
Insulin produced by the
Plasmid is taken up by
bacteria can be
bacteria
removed
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In the early part of the 19th century, patients suffering from diabetes often died in childhood as
there was no known treatment. In 1921, a young surgeon named Frederick Banting and his
assistant Charles Best discovered that insulin from animals could be used to treat humans.
1.
Suggest possible problems associated with using animal insulin to treat humans.
2.
It wasn’t until 1978 that insulin was produced by genetic engineering.
Explain why bacteria are ideal cells to use when carrying out this process.
3.
Explain why the enzyme used to remove the human insulin gene from the DNA is the same
enzyme used to cut the bacterial plasmid.
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4.
Genes can also be inserted into animals and plants.
Suggest reasons why scientists may want to do this.
5.
Trials have been carried out using genetic engineering to treat genetically inherited
conditions.
Suggest how genetic engineering can be used to treat conditions where faulty genes have
been inherited.
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Task 2a – Genetic testing for Huntington’s disease
Huntington’s disease is a life limiting condition that is hereditary. It is a disorder of the central
nervous system caused by a single faulty gene known as a gene mutation. If a patient has one
copy of the gene, they will suffer from Huntington’s later in life and will die from the disease as
there is no cure.
If one of the patient’s parents has Huntington’s disease, there is a 50% chance that any of their
children will get the disease.
The uncertainty of living with the knowledge that there is a 50% chance that you carry the gene
can be distressing but there is a DNA test available that can identify if a patient carries the gene.
However, not all people want to find out if they carry the gene. If the test is positive, it would be
very distressing as there is no cure for the disease. It may also prove difficult for the patient to get
a mortgage and life insurance to buy a house. Another thing to consider is that it creates moral
issues if they decide to start a family.
People who decide to get the test are first advised to discuss the options with a counsellor, close
family members and partners as it can have implications for them too.
Only patients over the age of 18 can make the decision about whether they want to be tested so
parents cannot have their children tested to see if they have inherited the gene.
If a patient’s grandparent has Huntington’s disease but no other family member has been tested or
shown symptoms of the disease, they are advised to think very carefully before considering the
DNA test.
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1.
Is Huntington's disease caused by a dominant or recessive gene?
2.
Why might a patient decide not to get the DNA test even if their parents do have it?
3.
Why might it prove difficult to get life insurance or mortgage if a patient has the test?
4.
Why do you think parents of a child who is under the age of 18 cannot get the test carried out
on the child?
5.
Why might knowing about having the gene cause a moral issue if they decide to start a
family?
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6.
Why is it advisable to carefully consider taking a DNA test if a grandparent has the condition
but no other family members have been tested or shown symptoms of the disease?
7.
Why do you think people decide to get tested?
8.
Do you think this test should be available?
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Task 2b – Genetic testing for Down’s syndrome
Down’s syndrome is a genetic condition caused by a chromosome mutation. In people with
Down's syndrome, all or some of the cells in their bodies contain 47 chromosomes, as there is
an extra copy of chromosome 21. This is known as trisomy 21.
Usually, cells contain 46 chromosomes. A child inherits 23 from the mother and 23 from the
father but in Down’s syndrome the child inherits 24 chromosomes from one parent due to a
mistake made during the production of their sex cells (sperm or egg). The additional genetic
material causes physical and developmental characteristics associated with Down's syndrome
and does reduce their life expectancy to 60 years.
The main factor that increases the chance of having a baby with Down's syndrome is the age
of the woman when she becomes pregnant. An increase in age of the woman increases the
risk of having a child with Down’s syndrome as below:
•
20 years of age has a risk of one in 1,500
•
30 years of age has a risk of one in 800
•
35 years of age has a risk of one in 270
•
40 years of age has a risk of one in 100
•
45 years of age has a risk of one in 50 or greater.
However, babies with Down's syndrome are born to mothers of all ages.
The uncertainty of going through pregnancy with the knowledge that there is a chance that
your child may have a chromosome mutation can be distressing. Pregnant mothers are offered
the opportunity to have a test to see if they have a high chance of having a child with a genetic
mutation such as Down’s syndrome.
The test involves a procedure called an ‘amniocentesis’ where a large needle is inserted into
the abdomen of the female and into the fluid surrounding the baby. A sample of the fluid is
then tested to see if the cells of the baby are ‘trisomy’. This is usually done between 15 and 20
weeks of pregnancy. However, not all people want to have an amniocentesis to find out if their
child has Down’s syndrome as it creates a moral issue if they decide to continue the
pregnancy.
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The diagram below shows the result of an amniocentesis where trisomy 21 can be seen –
there are three copies of chromosome 21 instead of two. This picture is called a karyotype.
1.
What risks could there be with having an amniocentesis?
2.
Why do you think it is not recommended to get the test done before 15 weeks of
pregnancy?
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3.
Why do you think people decide to get tested?
4.
Why might a pregnant mother decide not to have an amniocentesis?
5.
Why might it cause a moral issue if they continue with the pregnancy?
6.
Individuals suffering from Down’s syndrome are often infertile and cannot have children
of their own. Why do you think this is?
7.
Do you think this test should be available?
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Task 3a – Making choices on Genetic engineering
Genetic engineering divides people’s opinions. Some people agree with it, some people only
agree on some of its uses and some are totally against it.
Uses of genetic engineering that divides opinion are often Genetically Modified (GM) crops
and GM animals.
Divide your exercise book into 3 columns with headings, the first being ‘yes I agree’, the
second being ‘no I do not agree’ and the third column ‘reasons’. Cut out each of the
statements below and stick them into one of the first two columns based on whether you agree
or disagree with the statement. In the third column try to come up with a reason why you agree
or a reason why you do not agree for each statement.
Modified animals
GM crops could
could become the new
escape and breed
Modified animals can
with weeds making
be made disease
‘super weeds’
‘wonder pet’ and make
loads of money
resistant
The more we modify
animals the more we
We do not know what
learn to treat human
GM crops could do to
conditions
us if we eat them
GM crops can be
made that will grow in
GM crops can be
very dry
made to taste better
environments
and be bigger!
GM crops can be pest
Parents could pick
resistant so will not
genes for their babies
require expensive
making ‘Designer
pesticides
babies’
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Task 3b – The issues behind Genetic engineering
There are a number of economic, social and ethical issues concerning genetic engineering.
For each of the statements below you need to decide which issue(s) it relates by placing a ‘’ in
the box. Be ready to justify your answer to your teacher.
The issue
Economic
Modified animals could become the new ‘wonder
pet’ and make loads of money
GM crops could escape and breed with weeds
making ‘super weeds’
Modified animals can be made disease resistant
Parents could pick genes for their babies making
‘Designer babies’
GM crops can be made to taste better and be
bigger
GM crops can be pest resistant so will not require
expensive pesticides
GM crops can be made that will grow in very dry
environments
The more we modify animals the more we learn to
treat human conditions
We do not know what GM crops could do to us if
we eat them
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Social
Ethical