Genetic Engineering

I. Changing the Living World

• A. Humans are the ones responsible for directing the change among domestic animals and plants.

• B. The want for better “hunters,” “retrievers,” and large food crop resulted in selective breeding.– 1. selective breeding – allowing only the animals/plants

with desired traits to produce the next generation (taking advantage of the naturally occurring genetic variation)

II. Selective Breeding• A. Tool that were used during selective

breeding:– 1. Hybridization – crossing dissimilar individuals

to bring together the best of both organisms• a. Ex. Crossing a disease resistant plant with a large

food production

– 2. Inbreeding – continue breeding of individuals with similar characteristics to maintain desired characteristics• a. Can bring up recessive genetic defects

III. Increasing Variation• A. Breeders can also increase genetic variation by

inducing mutations, by using chemicals and radiation. – 1. Drugs that prevent chromosomal separation during

meiosis results in larger fruit– 2. Genetic mutated bacteria consume oil to help with oil

spills

In the beginning when Humans were trying to alter genetic code among animals and plants they left it all to

chance. Today with the technology & tools

scientists are able to be more precise with the genetic mutations they create

IV. Genetic Engineering• A. Genetic Engineering – making changes in the

DNA code of a living organisms. – 1. Using Recombinant DNA are taking two or more

sources and combining them into one molecule• a. Occurred by: viral transduction, bacterial transformation,

conjugation or in vitro

V. Extracting the Genes• A. The process occurs in several steps: 1st Get DNA– 1. DNA Extraction – simply done by chemical procedure– 2. Cutting DNA – cutting DNA into smaller fragments at

specific sequences “sticky ends” allows scientists to analyze the code and make changes. The DNA is cut using restrictive enzymes • a. can also mark the specific sequence with a probe (radioactive

labeled)

– 3. Insert Gene into Plasmid: place plasmid into a vector (i.e. bacterium) allow bacteria to reproduce by fission• a. require reverse transcriptase since bacteria do not read introns

VI. Analyze the Gene Sequence• A. Separating DNA – gel electrophoresis, a mixture of DNA

fragments is placed along one end and run through a gel that is charged. The DNA moves toward the positive end (anode), smaller the DNA fragments the farther is moves. • a. it is used to compared genomes of different individuals (RFLPs)

restriction fragment length polymorphisms

VII. Genetic Engineering: Changing DNA

• A. Knowing the sequence of an organism's DNA allows researchers to study specific genes compare them, and to try to discover the functions of different genes and gene combinations.

• The following are some techniques scientists use to read and change the sequence of DNA molecules.– 1. Reading the sequence – 2. Cutting & Pasting – 3. Making Copies (PCR-polymerase chain reaction)

IIX. Transferring DNA• A. There wouldn’t be a point to changing DNA if you

couldn’t put it back into a living cell.– 1. Bacteria can easily be transformed using recombinant DNA

(to produce medicines; insulin)– 2. Plants today are being infected by bacteria that have

altered DNA (create own insecticide)– 3. Most egg cells are large enough that DNA can be directly

injected into the nucleus. Inserting this foreign DNA can “knock out” the DNA normally found in the cell (disappointed results )

(livestock produce leaner meats or specific proteins in their milk)

IX. Applications of Genetic Engineering

• A. Genetic engineering has made it possible to transfer DNA sequences, including whole genes.– 1. 1986 Steven Howell inserted the gene that allows

fireflies to glow into a tobacco plant

• B. Transgenic organism is one that contains genes from other species.

Is this always a good thing for our ecosystem?

Will there be a large genetic variety anymore?

X. Cloning

• A. Clone a mammal—to use a single cell from an adult to grow an entirely new individual that is genetically identical to the organism from which the cell was taken.

• B. 1997 Scottish scientist Ian Wilmut cloned a multicellular organism.– 1. Wilmut’s technique is as follows: nucleus of an egg

cell is removed and a cell from the sheep to be cloned is fused with a cell. The fused cell begins to divide and the embryo is then placed in the reproductive system of a foster mother, where it develops normally

Why clone sheep?

• Dolly the sheep, was produced as part of research into producing medicines in the milk of farm animals.

• Researchers have managed to transfer human genes that produce useful proteins into sheep and cows, so that they can produce, for instance, the blood clotting agent factor IX to treat hemophilia or alpha-1-antitrypsin to treat cystic fibrosis and other lung conditions.