Application of gene technology

Transgenic organisms and gene therapy

Unit 4, AOS 2

Marina Kalcina

What do you think of when you look at this picture?

By the end of today’s lesson you will know about one aspect of gene technology & be

able to:• Describe the different

ways transgenics are made• List examples of transgenic

organisms• Explain how gene therapy

works and list diseases for which it has been used

• Debate issues surrounding the use of transgenic organisms and gene therapy

Artist: Patricia Piccininihttp://www.patriciapiccinini.net/

How are transgenic organisms made?Getting genes into animal cells

A transgenic organism is one in which a foreign gene has been inserted into it’s genome to enable production of a specific protein. There are 4 main ways transgenics can be made in animals:

• Microinjection• Electroporation• Fusion of vesicles• Gene gun

Microinjection

A glass micropipette is used to puncture a hole in the cell and nuclear membranes and insert the genes.

Allows only one cell to be treated at a time

Electroporation

A short electric shock makes many cells permeable at the same time.

This allows the DNA to enter the cell

What does permeable mean?

How is electroporation different to microinjection?

Fusion of vesicles

Vesicle is created where desired DNA is enclosed in a membrane.

Vesicle membranes fuse with cell membranes and DNA enters the cell.

The vesicles can be made to fuse with many cells at a time.

Gene gun

Gold or other metallic particles are coated with DNA of interest

The DNA covered metallic particles are then fired into the nucleus of a cell using a gene gun

How have bacterial transgenics helped us?

• http://www.biotechnologyonline.gov.au/biotechnologyonline/popups/int_splicing.html

• Insulin is a hormone diabetics need to inject every day • Too complex to be made in the lab• Limited amounts used to be obtained from pancreas of animals

being slaughtered for food• The human insulin producing gene was placed in a bacterial

plasmid, bacteria reproduced and made few billion copies of itself• Insulin extracted from bacteria for medical use• The animation above allows students to explore this.• Ask students to make a flow chart after working through the

animation

Some examples of transgenics

• GFP animals from the start• Bacteria used for insulin and some vaccines• Sheep with a human gene which causes their

milk to contain a blood-clotting protein which can then be extracted from milk to treat humans

• Silk worms that produce human collagen• Many examples – get students to research more

and present them?

Gene therapy

Gene therapy is the technique of delivering normal and fully functional genes to individuals to compensate for a disease causing mutation. It has the potential to treat or cure people suffering from a range of genetic conditions.

The functional gene has to be located, isolated and cloned in sufficient quantities and a suitable vector needs to be found to deliver the gene.

The inserted gene needs to be able to persist and function normally within the target cells

Gene therapy procedure and examples

• AIDS• Cystic

fibrosis• Cancer• Parkinson’s• Alzheimer’s• Arthritis

Somatic cell vs. germ-line gene therapy

Somatic cell gene therapy: • The process talked about so far• Alters the genotype of somatic

cells• Extremely difficult to insert new

genes into every cell or organ• The healthy gene cannot be passed

onto offspringGerm-line gene therapy:• Transformation of eggs or sperm• The healthy genotype will be

passed onto offspring• Extremely controversial• Not an accepted medical practice

Questions and activities to ask students to stimulate thinking in the higher order

• What do you think would be some risks associated with gene therapy?

• Write down some arguments ‘for’ and ‘against’ gene therapy.

• Organise debates! Split the class in half. One half will argue for transgenic organisms, the other half will argue against them.

• Debate: Is a tomato injected with an arctic fish gene to prevent it from frosting, still a tomato? Or, is the transgenic tomato still a suitable food for vegetarians?

Another activity:Present the following scenario:

Any gene researcher conducting experiments in an institute needs to have approval from the biosafety and bioethics committee. Imagine a research team is applying for permission to develop a particular transgenic organism….

• Split the students into groups of 5• Allocate the role of committee to 2 or

3 members of the group.• Allocate the role of research

applicants to 2 or 3 members of the group

Higher order thinking activity continued….Some points students may want to discuss in their groups:

Researchers Committee members

Name of the company for which you want to develop the transgenic organism?

What guidelines are the researchers to follow to ensure:• Safety to researchers in

lab• Safety to environment• Ethical issues are

addressed?

What transgenic organism would you like to develop and why?

What sorts of questions will be asked of the researchers?

How will we respond to questions the committee has?

• Once students have had time to talk about the points listed in the table, ask them to present their findings in a group role-play

• Members of the audience (rest of the class) can help the committee decide whether to agree to the researchers’ proposal

References and resources:

• ScienceAlert facebook page• Science Quest 4 textbook, Lofts & Evergreen 2007• Nelson Biology textbook, VCE units 3 & 4, Borger et al,

2006• Spotlight Biology textbook, VCE units 3 & 4, Joanne

Burke, 2007• Biotechnology online for the animation:http

://www.biotechnologyonline.gov.au/ biotechnologyonline/popups/int_splicing.html

• Google images