Use of recombinant DNA technology

Aqa p.256-61

Homework

• Hand in todays poster• Wsheet making an artificial gene• Wsheet exam q on pcr

• Green p.265-6• Red p.265• Optional – gene therapy using

artificial chromosomes stretch and challenge

Objectives

• How has genetic modification of organisms benefitted humans?

• What roles have genetically modified microorganisms, plants and animals played in the beneficial use of recombinant DNA technology?

Poster with list on please(hand in)

• Title; The use of recombinant DNA technology to produce transformed organisms that benefit humans.

• Divide into 4• On 3 sections include one or more

examples of microbes, plants and animals

• make a list with arguments for and against DNA technology from p260-1 OR do green p.261

• use the pink and green response cards to discuss ethics

plants

Microbes

Using technology to modify organisms

Recombinant DNA technology can now be used to alter the genetic make-up of organisms much more quickly.

Crop plants and domestic animals have been modified over generations using selective breeding, to produce organisms with desirable characteristics.

Some genetically modified organisms are already being produced. In 2006, 252 million acres of transgenic crops were grown globally.

Types of GM cropsSeveral different type of genetically-modified crops are currently being grown throughout the world. These include:

herbicide-resistant crops

disease-resistant crops

crops with increased nutritional value – these include Golden Rice.

pest-resistant crops – these include insect-resistant crops that have been engineered to produce a bacterial toxin that kills a specific pest.

Golden RiceRice that has been engineered to contain beta-carotene is known as Golden RiceTM. Beta carotene is converted into vitamin A when digested.

Golden Rice is thought to have potential benefits, as vitamin A deficiency currently affects a large number of people in economically less developed countries.

The production of Golden RiceRice plants naturally contain the gene for beta-carotene. This gene is expressed in the photosynthesizing parts of the plants. However, it is not expressed in the endosperm (grain).

The production of beta-carotene relies on the presence of several enzymes. Not all of the enzymes are naturally available in the endosperm.

In order to complete the biosynthetic pathway to restore the production of beta-carotene, scientists inserted two genes from other organisms into the rice genome, to complete the biosynthetic pathway.

Using genetically modified bacteria

Production of drugsTransgenic animals and plants can be modified to produce useful pharmaceuticals. This is known as pharming.

For example, alpha-1-antitrypsin protects the lungs from damage during infection. Transgenic sheep can be produced that contain the gene for this protein.

The gene can be pre-programmed to be expressed only in the mammary gland cells and secreted in milk. It can be extracted, purified and used for treating emphysema sufferers.

XenotransplantationXenotransplantation is the transfer of organs or tissues into humans from other species, including pigs.

Transplanted organs are often rejected by the new host’s immune system, as antigens on the cells’ surface will be recognized as foreign.

Recombinant DNA technology has been used to engineer pigs that lack an enzyme that is thought to contribute to transplant rejection.

It is thought that with future developments xenotransplantationmay be able to provide a large number of organ transplants.

The GM debate

Opinions on GM organisms

Genetic modification: you vote