GENETIC ENGINEERING

Genetic engineering examples include taking the gene that programs poison in the tail of a scorpion, and combining it with a cabbage.  These genetically modified cabbages kill caterpillers because they produce scorpion poison (insecticide) in their sap. Potatoes have been engineered to resist pests by producing a chemical coded for by a frog gene.

Genetic engineering also includes insertion of human genes into sheep so that they secrete alpha-1 antitrypsin in their milk - a useful substance in treating some cases of lung disease.

Genetic engineering works because there is one “language of life” (universal genetic code):  human genes work in bacteria, monkey genes work in mice, pepper plant genes work in bananas and spider genes work in goats.  There is no limit, in theory, to what genetic engineering could produce!

Genetic engineering has created a chicken with four legs and no wings. Scientists were studying the genes that control limb formation in embryo development.

What is genetic engineering?• the use of technology to

change the genetic make-up of cells to produce a new and useful result

Is genetic engineering a new idea?

• Humans have been selecting and breeding organisms with desired traits for thousands of years. Some examples:– “Seedless” oranges– Pluots: Plum-apricot hybrid

Comparing selective breeding and genetic engineering

In selective breeding (think Mendel’s peas), we are combining two traits to get a mixture of results

In genetic engineering, a single gene, a half page recipe in the 52-thousand-page set of recipe books, can direct the plant to make new traits or remove them

Comparison

How does genetic engineering work?• First, a desired gene in an

organism must be identified and isolated.

• Once isolated, the gene is further modified in the lab

• The modified gene is inserted into a vector (like a bacterium or virus) and the vector “delivers” the gene to the desired organism.

http://cmbi.bjmu.edu.cn/cmbidata/therapy/research/re02/021.htm

How it works:

Example: Insulin Production

• Protein that codes for insulin production is cut from human DNA using restriction enzyme (EcoRI)

Example: Insulin Production

• Plasmid (from E.coli) is also cut with EcoRI– Sticky ends are now

exposed on both human DNA and plasmid DNA

Example: Insulin Production

• Ligase seals sticky ends of desired DNA and plasmid DNA

• Recombinant DNA is inserted into a bacterium

How Did They Do That?1. Jellyfish make a protein that

causes them to glow in some types of light.

2. The glowing gene is taken from a jellyfish cell and inserted into an empty virus cell

3. The genetically engineered virus attaches itself to the fertilized mouse egg cell.

4. The virus delivers the glowing gene into the egg cell nucleus, where it joins the mouse DNA.

5. The genetically engineered mouse egg grows into an adult mouse which will make the glowing protein.

Virus

Jellyfish cell

Mouse cell

Virus inserting their DNA into a cell

Transgenic Organisms• Any organism that contains genes from a

different organism (traits not normally found in that species) is a transgenic organism.

Extended shelf-life tomato (Flavr-Savr)

Herbicide resistant soybean (Roundup Ready)

What are some possible uses of genetic engineering?

• Improving crops

• Creating bacteria that can produce medicine

• Increasing food supplies

• Alternative energy sources

• Human body parts for transplant

• Preventing human diseases (gene therapy)

Improving Crops

• Crops may be improved by making them resistant to certain factors, like insects, drought, herbicides, or frost

• Crops may also be “improved” by engineering them to produce things like vitamins that are not normally found in the species

Agriculture Transgenics On the Market

Source: USDA

Insect resistant cotton – Bt toxin kills the cotton boll worm• transgene = Bt protein

Insect resistant corn – Bt toxin kills the European corn borer• transgene = Bt protein

Normal Transgenic

Bt Corn

Virus resistance - papya resistant to papaya ringspot virus• transgene = virus coat protein

Source: Monsanto

Herbicide resistant crops Now: soybean, corn, canola Coming: sugarbeet, lettuce, strawberry alfalfa, potato, wheat (2005?)• transgene = modified EPSP synthase or phosphinothricin-N-acetyltransferase

The flounder is a fish that live in icy seas. It has a gene that stops it from freezing to death.

Strawberries are soft fruits that can easily be damaged by frost.

1. Fish antifreeze gene is inserted into a plasmid.

2. Plasmid with gene is placed into a bacterium.

3. The bacterium with the flounder gene is used to “infect” strawberry cells.

Strawberry cell with Antifreeze gene

4. The infected cells grow into a frost-resistant strawberry plant.

Fishy Strawberries- Making a frost resistant strawberry

Can genetic engineering end malnutrition and vitamin deficiencies?

• Golden rice is genetically modified to contain large amounts of beta-carotene, which is converted by the body into vitamin A

• Vitamin A is important to factor for good vision (particularly night vision) and a strong immune system.

• Many individuals in poor and underdeveloped countries receive inadequate amounts of vitamin A in their diets, leading to higher incidences of blindness.

Creating bacteria that can produce medicine

• As you saw in a previous example, bacteria have already been engineered to produce insulin proteins that can be injected by human diabetics to control their diabetes.

• Some other examples:– Bacteria produce human growth hormone to treat

types of dwarfism– Producing interferon for cancer treatments

Increasing Food Supplies• In many parts of the world, hunger is

rampant due to limited food resources.

• One possibility is to produce fish species that mature more quickly so that they can breed and create new generations sooner.

Salmon

http://fish.dnr.cornell.edu/nyfish/Salmonidae/salmonidae.html

Alternative Energy Sources

• Fossil fuels are dwindling

• Ethanol (the current alternative) comes mostly from corn, which is used as a major food crop in most countries

• It would be most beneficial to use “waste” and “leftovers” for fuel.

http://www.teachersdomain.org/resource/biot09.sci.engin.systems.ethanol/

Creating Human Body Parts for Transplant

• Individuals in need of an organ transplant can often wait years for a donor organ.

• Organs from other species is not usually an option because the immune system attacks such transplants as “foreign”.

• Scientists are researching the possibility of inserting human genes into other species so that they can grow “human” organs for transplant.

What’s Going On Here?

Photo of mouse growing a "human ear" - a shape made of cartilage

Some Other Possibilities

• Earlier this decade, scientists at the University of Minnesota created pigs that pumped human blood (specifically human hemoglobin)

Preventing and Curing Human Diseases• Several human diseases (like cystic fibrosis

or breast cancer) have a genetic component.

• Individuals with these disorders have a mutation, or mistake, somewhere in their DNA sequence

• Replacing these mutated sequences with “normal” sequences should fix the problem

• This process is known as gene therapy.

What is Gene Therapy?1. Individuals with cystic fibrosis

have a faulty gene.

2. To fix the problem, a copy of the same gene from a healthy person is spliced into a virus.

3. The patient’s lungs are infected with the virus. It delivers the working gene into the patient’s cells. The cells can then make the right protein, and the patient can breathe normally.

Patient’s cell

Patient’s DNA

Faulty Gene

Virus DNA

New working gene

Patient’s DNA

Virus DNA with new gene

Will We Be Able To Cure Cancer With Gene Therapy?

Lung cancer cells (530x). These cells are from a tumor located in the alveolus (air sac) of a lung.

                             

Cancer happens when body cells grow out of control. Scientists have found a gene called p-53 which normally keeps cells under control. Some individuals with cancer may have a non-working copy of p-53. Experts are now looking for a way to cure cancer by modifying faulty DNA to make the p-53 gene work.

Breast Cancer

What Else?Using the jellyfish protein to make a naturally glowing Christmas tree!

Genetically engineered moths that pass on deadly disease genes to their relatives so they die and won’t be able to destroy crops!

Adding a gene from insect killing bacteria to cotton so that insects who eat cotton will be poisoned!

A gene from a spider has been inserted into some goats. Their milk now contains tiny strands of spider silk which can be made into a strong, stretchy rope.