1. Genetic Engineering and Selective Breeding Notes

2. Selective Breeding: Breeding Plants and Animals for the Benefit of Humans
Selective Breeding: Selecting individuals with desired traits to produce offspring for the next generation
Used to produce most crops (corn, wheat…)
Used to produce all breeds of domestic animals – dogs, horses, cats, sheep, cattle
Also called artificial selection

3. developed over 800 varieties of plants.
All of the different plants produced from wild mustard by selective breeding!
Luther Burbank
( )
developed over 800 varieties of plants.

4. Limits of Selective Breeding
It can be a slow process, taking lots of time and many generations to get the traits that you want.
Can not mix traits from two different species
Can result in undesirable offspring or traits
Example: Might want plants that are drought resistant; however, end up with drought resistant plants that don’t produce many seeds!

5. Two Types of Selective Breeding: 1. Inbreeding
Inbreeding: crossing two individuals with similar traits.
Advantages:
Desired trait is enhanced and preserved through many generations
Disadvantages:
Decreases genetic variation which could lead to vulnerability to disease
Homozygous recessive traits that are unwanted or unhealthy are more likely to show up.

6. This entire crop was wiped out in weeks by one disease!
Disadvantages of Inbreeding
Because of the loss of genetic variation within this crop, all were equally vulnerable to disease.
This entire crop was wiped out in weeks by one disease!

7. Two Types of Selective Breeding: 2. Hybridization
Hybridization: crossing 2 dissimilar, but related organisms
Offspring called hybrids
Advantages:
Usually stronger/hardier than parents –
known as hybrid vigor
Disadvantages:
May promote the loss of native species if released into the wild.

8. Hybridization Examples
1. African catfish (left) grows faster than Thai catfish.
2. Thai catfish (middle) has better tasting flesh than African catfish.
3. Hybrid (right) grows fast & has good tasting flesh.
Problem: It has been released into rivers of Thailand and is disrupting food chains.

9. Other hybrids: The horse and donkey are mated to produce a mule
Other hybrids: The horse and donkey are mated to produce a mule. The lion and tiger are breed to produce a Liger or Tigon. The horse and zebra are mated to produce a zorse

10. Genetic engineering: changing an organism’s DNA to make it more beneficial to humans

11. Genetic Engineering: Recombinant DNA and Transgenic Organisms
Recombinant DNA: DNA made from two separate species
A gene from one organism is “recombined” with another organisms DNA.
Transgenic Organism: any organism that contains recombinant DNA.
These new gene combinations could never be possible in nature

12. Researchers isolate a gene from an organism that has the trait they want to give to a plant.
and cells are grown
Transgenic Plants

13. Just for Fun?- a glowing tobacco plant

14. What’s Next on Your Plate?
What’s Next on Your Plate?
What genes do we want them to have?
Insect, Herbicide, and Fungal resistance
Drought resistance
Product quality
New vitamins or other nutritional benefits
Longer Shelf Life (Flavr Savr Tomato)

15. Transgenic Organisms: Plants
Example: Rice plants and daffodils can not
cross pollinate with each other in nature.
The rice on the right is called Golden Rice. Its genome contains the gene for producing vitamin A from daffodils.
This rice is healthier for people who do not get enough vitamin A in their diets.

16. Transgenic Organisms: Animals
Animals are now being produced with genes that increase milk production and muscle mass (meat). Problem: unhealthy; legs cannot support weight

17. Transgenic Organisms: Animals
Genetically engineered mice used in cancer research:
Contain gene from glowing jellyfish
Glow when a cancer is growing in them
Mice are given chemotherapy drugs; if the tumor shrinks, they glow less & less
Mice don’t die from the cancer or the chemotherapy drugs
Mice expressing “glow” gene from jellyfish.
Glowing jellyfish

18. Transgenic Organisms: Bacteria
Used to produce important medicines:
Insulin for diabetics
Human growth hormone
Anticoagulants for (for treating heart attack patients)
Bacteria cultures
Insulin

19. Other Uses for Transgenic Bacteria
What’s Next?
The artificial sweetener in most diet sodas phenylalanine is already being made by transgenic bacteria.
How about making a transgenic bacteria that when introduced to the mouth, prevents cavities?
What about transgenic bacteria able to clean up oil spills?

20. Dangers of Transgenic Organisms
Ethical problem (should we)
Transgenic bacteria could be used to create biological weapons
Insertion of gene may interfere with workings of other genes causing disease
A superior transgenic organism that escaped into the environment may damage the ecosystem (food chains)

21. Genetic Engineering and the Future
Got Silk? Video
Spider silk in goat’s milk

22. Creating hybrids to study evolutionary relationships
Hybrid form is similar to types found in archeological digs.
Hugh Iltis
Corn domestication started around 10,000 years ago in central America. Creating hybrids between modern corn and the wild grass teosinte has produced fertilize hybrids. Analyzing the genetic differences between the hybrids and parent stocks, has shown that single gene mutations are responsible for:
Changing a bushy phenotype (seen in teosinte) to a single stalk phenotype (corn)
Turning teosinte seeds inside out—the hard outer casing became the central cob.