GENETIC ENGINEERING

1. GENETIC ENGINEERING Chapter 13

2. Selective Breeding • Humans use selective breeding to pass desired traits on to the next generation of organisms. • Allows only those animals with desired characteristics to produce the next generation. • 2 Types of Selective breeding: • Hybridization • Inbreeding

3. Hybridization • Hybridization – cross breeding non-similar individuals that bring together the best traits of both organisms. • Produces hybrids (mixed organisms) that are often BETTER than either parent… • disease resistant plants • plants with higher food producing capacity

4. Inbreeding • Inbreeding- continued breeding of individuals with similar characteristics • Used to maintain the desired characteristic of an organism. • Ex Dog breeding (beagles, poodles, golden retrievers, etc.) • Risks of inbreeding: • genetically similar breeds increase the likelihood of passing on recessive alleles for genetic defects

5. Increasing Variation • Breeders can increase the genetic variation in a population by causing mutations, which are the ultimate source of genetic variability. • mutations are inheritable changes in DNA that occur spontaneously • radiation or chemicals may be used • If lucky, breeders can produce a few mutants with desirable characteristics that are not found in the original population

6. Manipulating/ Changing DNA • Genetic engineering is used to make changes in the DNA. • First, the DNA is extracted/ removed from an opened cell. • Restriction enzymes are then used to cut the DNA at a specific section of nucleotides. • The fragments are then separated and analyzed using gel electrophoresis (used to compare genomes of different organisms)  this way scientists can locate & identify single genes out of millions in a genome.

7. Cutting DNA with Restriction Enzymes

8. Separating DNA with Gel Electrophoresis

9. DNA Sequencing • In DNA sequencing, a complementary DNA strand is made using a small proportion of fluorescently labeled nucleotides.

10. Cutting, Pasting, & Making Copies of DNA • Recombinant DNA is produced by combining DNA from different sources. • These DNA sequences are joined by using enzymes to splice/ squeeze the DNA together • A polymerase chain reaction (PCR) allows biologists to make many copies of a particular gen • A few dozen cycles of PCR can produce millions of copies of a DNA sequence

11. During Cell Transformation, a cell incorporates/ includes foreign DNA into its own DNA. A plasmid (circular DNA) is made, and contains a genetic marker, which distinguishes the human DNA from the bacterial DNA. One way to make recombinant DNA is to insert a human gene into bacterial DNA. The new combination of genes is then returned to a bacterial cell, and the bacteria can produce the human protein.

12. Knock-Out Genes • Recombinant DNA can replace a gene in an animal’s genome. When recombinant DNA is inserted into the target location, the host cell’s original gene is lost or “knocked out” of its place.

13. Applications of Genetic Engineering • Transgenic Organisms: organisms that contain some genes from other organisms

14. Transgenic Organisms are the basis for Biotechnology!!! • Transgenic bacteria now produce a host of important substances useful for health & industry. • Human insulin, growth hormone, and clotting factor are now produced by transgenic bacteria. • Transgenic animals have been used to study genes and improve the food supply. • These animals often grow faster and produce LESS fatty meat. • Transgenic plants are an important part of our food supply. • Many transgenic plants produce a natural insecticide, so the crops do not have to be sprayed with pesticides.

15. Cloning –a member of a population of genetically identical cells produced from a single cell.

16. Cloning…Meet Dolly the Sheep!!!