Modifying GenesModifying GenesHow can they be changed?

1. Genetic Engineering1. Genetic EngineeringReplacing genes for desired

traits…◦Must know exact location

Gene map (genome project)

Example 1:◦Cloning: Identical copy of gene or

entire organism Organ transplants Organism can have genetic

disorders/health issues

Dolly the SheepDolly the SheepFirst cloned mammal

(from a mammary gland), 1997

1. Genetic Engineering1. Genetic EngineeringExample 2:

◦Gene Therapy Normal gene inserted to abnormal or

absent gene location Host often rejects new foreign material

1. Genetic Engineering1. Genetic EngineeringExample 3:

◦Stem cells: Undifferentiated – can become specialized (become any type cell)

◦Embryos & adults ◦Can replace damaged tissues

February 2004    242 donor eggs --> 30 blastocysts --> 1 stem cell May 2005    181 donor eggs --> 31 blastocysts --> 11 stem cells

 10 donor eggs fused with skin cells      from 9 patients with spinal injuries & 1 with diabetes all formed embryonic cell layers and       each was compatible with patients immune systems      and was genetically matched to donors.

1. Genetic Engineering1. Genetic EngineeringGoals:

◦Plants: Resist insects, more nutritious, keep longer

◦Animals: Bigger, grow faster, disease resistant

◦Bacteria: Produce insulin or growth hormone

◦Humans: Replace mutant genes (Tay-Sachs, CF, Sickle Cell Anemia) [in theory]

2. Selective Breeding2. Selective BreedingMethod of artificially selecting

and breeding only organisms with a desired trait to produce the next generation.

Most all domesticated animals and most crop plants

2. Selective Breeding2. Selective BreedingHybridization: Combining two

desired traits of an org. into one generation

Usually between two diff (but similar) species.

Plant breeders can cross a large yellow pepper and a Plant breeders can cross a large yellow pepper and a small red pepper to create a hybrid that is large and red. small red pepper to create a hybrid that is large and red. In this case the traits for size and red color are dominant In this case the traits for size and red color are dominant (yellow is a recessive trait). Traits like nutritional levels (yellow is a recessive trait). Traits like nutritional levels operate under the same laws, but are far more complex operate under the same laws, but are far more complex to work with.to work with.