13.1 Changing the Living World

1. Selective Breeding

• Allowing only those animals with desired characteristics to reproduce

• Example: breeding dogs

2. Selective Breeding

• Luther Burbank:– Developed disease-resistant potatoes– Went on to develop 800+ varieties of plants

3. Selective Breeding

• Hybridization:– Crossing dissimilar

individuals to bring out the best of both organisms

– Hybrids are produced• Burbank’s plants:

disease resistant and food producing

4. Selective Breeding

• Inbreeding– Continued breeding of individuals with similar characteristics– Breeds of dogs are maintained through inbreeding

• Serious problems can arise– Two recessive alleles for a disease can be passed on more easily– Joint problems and blindness

5. Increasing Variation

• Variation can be introduced by inducing mutations• Induce mutation through radiation and chemicals• New Bacteria

– Oil “eating” bacteria– Caused variation which allowed some bacteria to digest oil– Cleaning of oil spills

6. New plants

• Polyploidy– Causes chromosomes to not split apart

• Creates 3N or 4N individuals

– Usually fatal, but plants survive– These plants can be stronger and larger than

normal, diploid plants

13.4 Applications of Genetic Engineering

1. Transgenic Organisms

• Transgenic: contains genes from other species

• Tobacco plant with gene to cause it to fluorescently glow

Transgenic Organisms

2. Transgenic Organisms

• Microorganisms:

– Bacteria are commonly used because they are small and easy to grow

3. Transgenic Organisms

• Microorganisms– Can be used to

produce insulin, growth hormone and clotting factor easily

– Human genes to produce these compounds were inserted into the bacteria

4. Transgenic Organisms

• Animals– Mice with immune

systems similar to humans

– Allows scientists to study the effects of diseases on the immune system

– Livestock with growth hormone to grow larger and faster

5. Transgenic Organisms

• Plants– 52% of the soy beans

and 25% of corn were genetically modified

– Contain natural insecticide so the crop does not need to be treated with pesticides

– Resistant to weed-killing chemicals

• The plant can still grow while weeds are killed

6. Cloning

• producing a genetically identical individual from a single cell

• 1997 Ian Wilmut cloned a sheep and named her Dolly

7. What happens during cloning?

• Nucleus from one cell is put into an egg cell where the nucleus has been removed

• The cell begins to divide and produce a new individual, genetically identical to the donor

8. Cloning

• One hope for cloning is to help endangered species

• Controversial because cloned animals may have genetic defects and health problems