Genetic Engineering Genetic Engineering and and

Selective Breeding Selective Breeding NotesNotes

Selective Breeding:Selective Breeding:Breeding Plants and Animals forBreeding Plants and Animals for

the Benefit of Humans the Benefit of Humans

Selective BreedingSelective Breeding: Selecting individuals with desired : Selecting individuals with desired traits to produce offspring for the next generationtraits to produce offspring for the next generation

a.a. Used to produce most crops (corn, wheat…)Used to produce most crops (corn, wheat…)

b.b. Used to produce all breeds of domestic animals – Used to produce all breeds of domestic animals – dogs, horses, cats, sheep, cattledogs, horses, cats, sheep, cattle

c.c. Also called Also called artificial selectionartificial selection

All of the different plants produced from wild All of the different plants produced from wild mustard by mustard by selective breedingselective breeding!!Luther

Burbank(1849-1926)developed over 800

varieties of plants.

Limits of Selective BreedingLimits of Selective Breeding

1.1. It can be a slow process, taking lots of It can be a slow process, taking lots of time and many generations to get the time and many generations to get the traits that you want.traits that you want.

2.2. Can not mix traits from two different Can not mix traits from two different speciesspecies

3.3. Can result in undesirable offspring or Can result in undesirable offspring or traitstraits

a.a. ExampleExample: Might want plants that : Might want plants that are drought resistant; however, are drought resistant; however, end up with drought resistant end up with drought resistant plants that don’t produce many plants that don’t produce many seeds!seeds!

Two Types of Selective Two Types of Selective Breeding: Breeding:

1. Inbreeding1. InbreedingInbreedingInbreeding: crossing two individuals with similar : crossing two individuals with similar

traits. traits. • AdvantagesAdvantages::

1.1. Desired trait is Desired trait is enhancedenhanced and and preservedpreserved through many generationsthrough many generations

• DisadvantagesDisadvantages::1.1. Decreases genetic variation which could lead Decreases genetic variation which could lead

to vulnerability to diseaseto vulnerability to disease2.2. Homozygous recessive traits that are Homozygous recessive traits that are

unwanted or unhealthy are more likely to show unwanted or unhealthy are more likely to show up.up.

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!

Disadvantages of InbreedingDisadvantages of Inbreeding

Two Types of Selective Breeding: Two Types of Selective Breeding: 2. Hybridization2. Hybridization

HybridizationHybridization: crossing 2 dissimilar, but : crossing 2 dissimilar, but related organismsrelated organisms

1.1. Offspring called Offspring called hybridshybrids

• AdvantagesAdvantages::1.1. Usually stronger/hardier than parents – Usually stronger/hardier than parents – 2.2. known as known as hybrid vigorhybrid vigor

• DisadvantagesDisadvantages::1.1. May promote the loss of native species May promote the loss of native species

if released into the wild.if released into the wild.

Hybridization ExamplesHybridization 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.

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

Genetic engineeringGenetic engineering:: changing an organism’s changing an organism’s DNA to make it more DNA to make it more beneficial to humansbeneficial to humans

Genetic Engineering: Genetic Engineering: Recombinant DNARecombinant DNA and and Transgenic Transgenic

OrganismsOrganisms

1.1. Recombinant DNARecombinant DNA: DNA made from : DNA made from two separate speciestwo separate species

a.a. A gene from one organism is A gene from one organism is “recombined” with another organisms “recombined” with another organisms DNA.DNA.

2.2. Transgenic OrganismTransgenic Organism: any organism : any organism that contains recombinant DNA.that contains recombinant DNA.

a.a. These new gene combinations These new gene combinations could never be possible in naturecould never be possible in nature

Researchers isolate a gene from an organism that has the trait they want to give to a plant.

and cells are grown

Transgenic Plants

Just for Fun?- a glowing tobacco plantJust for Fun?- a glowing tobacco plant

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)

http://archives.cbc.ca/IDD-1-75-1597/science_technology/genetically_modified_food/

Transgenic Organisms: Transgenic Organisms: PlantsPlants

The rice on the right is

called Golden RiceGolden 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.

Example:Example: Rice plants and daffodils can not Rice plants and daffodils can not cross pollinate with each other in nature.cross pollinate with each other in nature.

Transgenic Organisms: AnimalsTransgenic Organisms: Animals

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

Transgenic Organisms: AnimalsTransgenic Organisms: Animals

1.1.Genetically engineered mice Genetically engineered mice used in cancer research:used in cancer research:

a.a. Contain gene from glowing Contain gene from glowing jellyfishjellyfish

b.b. Glow when a cancer is growing Glow when a cancer is growing in themin them

c.c. Mice are given chemotherapy Mice are given chemotherapy drugs; if the tumor shrinks, drugs; if the tumor shrinks, they glow less & lessthey glow less & less

2.2. Mice don’t die from the cancer or Mice don’t die from the cancer or the chemotherapy drugsthe chemotherapy drugs

Mice expressing “glow” gene from jellyfish.

Glowing jellyfish

http://www.pbs.org/wgbh/nova/baby/

Transgenic Organisms: BacteriaTransgenic Organisms: Bacteria

Used to produce important Used to produce important medicinesmedicines::

a.a. Insulin for diabeticsInsulin for diabetics

b.b. Human growth hormoneHuman growth hormone

c.c. Anticoagulants for (for Anticoagulants for (for treating heart attack treating heart attack patients)patients)

Bacteria cultures

Insulin

The artificial sweetener in most The artificial sweetener in most diet sodas diet sodas phenylalaninephenylalanine is is already being made by already being made by transgenic bacteria. transgenic bacteria.

Other Uses for Transgenic Bacteria Other Uses for Transgenic Bacteria What’s Next?

How about making a transgenic bacteria that when introduced to the mouth, prevents cavities?

What about transgenic bacteria able to clean up oil spills?

Dangers of Transgenic OrganismsDangers of Transgenic Organisms

Ethical problem (should we)Ethical problem (should we) Transgenic bacteria could be used to Transgenic bacteria could be used to

create biological weapons create biological weapons Insertion of gene may interfere with Insertion of gene may interfere with

workings of other genes causing diseaseworkings of other genes causing disease A superior transgenic organism that A superior transgenic organism that

escaped into the environment may escaped into the environment may damage the ecosystem (food chains)damage the ecosystem (food chains)

Genetic Engineering Genetic Engineering and the Futureand the Future

Got Silk? VideoSpider silk in goat’s milk

Creating hybrids to study Creating hybrids to study evolutionary relationshipsevolutionary relationships

Hugh IltisHugh 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.

Hybrid form is similar to types found in archeological digs.