Teacher Resource 8: Genetic Engineering

Teacher Resource 8

Genetic engineering

This activity is for higher learners only and covers learning outcome B6.2e.

Learners work in groups of 2 or 3. Each has a worksheet that they can cut out the statements explaining the process of genetically engineering insulin, including the use of antibiotic marker genes to select plasmids containing the insulin gene.

Learners work together to place the statements in the correct order.

Each group then uses various art/craft resources such as Plasticine, wool, pipe-cleaners, straws, card etc. to model the process. Digital cameras/video recorders can be used to take snapshots of each stage of the process. Learners can either use one image for each statement to make a storyboard/cartoon describing the process, or can take numerous snapshots and put together a moving 'film' that can be shown to the class whilst each stage is narrated by a learner from the group.

Once completed, learners complete the questions on the second part of the worksheet individually.

Teacher preparation: Photocopy the worksheets, one per learners (each page should be on a separate piece of paper, not back to back as the first part will be cut out by learners). IT facilities and digital cameras will need to be booked prior to the lesson. A range of art/craft resources to model each stage of genetic engineering will need to be collected and made available for learners.

Answers

Card sort

1.Restriction enzymes cut the donor human DNA at each end of the insulin gene.

2.Sticky ends (exposed, unpaired bases) are formed on the ends of the DNA sections. (Note this could also be acceptable as the third point.)

3.The same restriction enzyme is used to cut open a loop of bacterial DNA called a plasmid, which contains an antibiotic marker gene.

5.The human insulin geneand open plasmid loop are mixed together with DNA ligase.

6.DNA ligase joins the sticky ends of DNA fragments together. Some loops will close before the insulin gene has been attached, others close after the insulin gene attached.

7.The loops of DNA are then inserted into a new bacterium (vector)

8.The bacteria are transferred to an agar plate containing the antibiotic that the antibiotic resistance genes codes for.

9.The bacteria are allowed to grow. Any colonies of bacteria that grow on the plate must contain the Abresistant gene and therefore the human insulin gene.

10.These bacteria are now called transgenic bacteria as they have DNA from another organism. They can now be grown in large numbers commercially and the insulin collected.

Questions

1.For each key term, write a definition.

Key term / Definition
Restriction enzyme / An enzyme that cuts DNA at a particular base sequence
Ligase enzyme / An enzyme that joins pieces of DNA with the same sticky ends together
Sticky end / A section of exposed, unpaired bases on the ends of a strand of DNA
Resistance marker / Something (usually a gene) to identify genetically engineered bacteria
Plasmid / A circular piece of DNA from a bacterium
Vector / Something (usually a bacterium or virus) that carries DNA into a cell.

2.What is the reason for using bacteria to produce genetically engineered hormones such as insulin?

Bacteria grow very fast so can produce huge quantities of hormone quickly and cost effectively.

3.Give two examples of vectors.

plasmids, viruses (most commonly use). There are others yeast artificial chromosomes YACs, bacterial artificial chromosomes BACs etc.

4.Give an example of a beneficial characteristic that could be incorporated into;

a)a crop

b)an agricultural animal

a)pest resistance, herbicide resistance, drought tolerance, salt tolerance, sweetness, disease resistance, increased yields etc.
b)pharmaceutical products in milk, disease resistance, increased growth over short time period, etc.

5.How might genetic engineering to form genetically modified crops be useful in treating nutrient deficiency diseases in certain countries?

Crops can be genetically modified to contain a number of nutrients that wouldn't normally be found in the crop for example: Golden rice produces beta-carotene from a gene taken from a daffodil. This beta-carotene is used to make vitamin A in the body, lack of which may lead to blindness.
For countries where limited crops can be grown, and often only one staple crop such as rice is grown as a result limiting the variety and amount of nutrients the people get, genetic engineering can increase the variety of essential vitamins and minerals in peoples diet leading to fewer deficiency diseases.