Ch 13 Genetic Engineering

Vocab: selective breeding, hybridization, inbreeding, genetic engineering, restriction enzyme, gel electrophoresis, recombinant DNA, polymerase chain reaction (PCR), plasmid, genetic marker,

transgenic, clone

13-1 Changing the Living World

Humans use selective breeding, which takes advantage of naturally occurring genetic variation in plants, animals, and other organisms, to pass desired traits to the next generation of organisms.

• Ex: dog breeding, horse breeding – choose parents for their traits, attempts to make disease resistant plants that have a high production rate

• Hybridization = crossing dissimilar organisms

• Inbreeding = continued breeding of individuals with similar characteristics… has resulted in the combination of recessive alleles with genetic defects: weepy eyes in dogs

Inbreeding Persian Catflat face= breathing problems

Shar-peiHuge rolls of skin=Skin disease Basset hound

Droopy, baggy eyes=Prone to eye infection

• Breeders can increase the genetic variation in a population by inducing mutation which are the ultimate source of genetic variability… use radiation and chemicals.

– New bacteria – oil-digesting to clean up oil spills

– Polyploidy plants – larger and stronger plants

13-2 Manipulating DNA

• Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules. Different techniques are used to extract DNA from cells, to cut DNA into smaller pieces, to identify the sequence of bases in a DNA molecule, and to make unlimited copies of DNA.

Genetic engineering = making changes in the DNA code of a living organism

• Extract DNA from cells

• Cutting DNA with restriction enzymes

• Separate DNA using gel electrophoresis

• Identify the sequence using different dyes that attach to nitrogen bases

• Make copies using polymerase chain reaction

Restriction Digest and Gel Electrophoresis

DNA sequencing

13-3 Cell Transformation

During transformation, a cell takes in DNA from outside the cell. This external DNA becomes a component of the cell’s DNA.

Transformation

• Scientists can synthesize a DNA strand and connect it to a circular DNA molecule known as a plasmid… which can be found naturally in bacteria. This bacteria can then be injected into a plant, and will insert its DNA into the plant.

• If transformation is successful, the recombinant DNA is integrated into one of the chromosomes of the cell.

13-4 Applications of Genetic Engineering

Genetic engineering has spurred the growth of biotechnology, which is a new industry that is changing the way we interact with the living world.

• Humans construct organisms that are transgenic and have genes from other species.

• Transgenic bacteria are being used to produce insulin, growth hormone, and clotting factor.

• Transgenic animals: mice, livestock

• Transgenic plants: 52% of soybeans and 25% corn is transgenic or genetically modified.

Clone = a member of a population of genetically identical cells produced from a single cell.

Cloning animals

• Bacteria naturally clone as do plants, multicellular organisms are more difficult; 1997 Dolly the sheep was cloned

• The possibilities raise many ethical and moral issues.