Ch. 13 Genetic Engineering Unit 4 Genetics Ch. 13 Genetic Engineering

Selective Breeding Selective breeding - allowing animals with desired characteristics to reproduce It takes advantage of naturally occurring genetic variation in plants, animals, etc.

Selective Breeding Humans use selective breeding to pass desired traits on to the next generation of organisms Nearly all domestic animals (horses, cats, etc.) & most crop plants have been produced by selective breeding

 Selective Breeding Hybridization - crossing dissimilar individuals to bring together the best of both organisms The organisms produced, hybrids, are usually hardier than both parents

Selective Breeding Inbreeding - continued breeding of individuals with similar characteristics Many breeds of dogs are maintained by inbreeding It helps to ensure the characteristics of each breed are preserved

Increasing Variation Selective breeding can increase genetic variation in a population by causing mutations to occur SB was used to create oil-eating bacteria, used to clean up oil spills

Manipulating DNA Scientists study & change DNA molecules Different techniques are used to extract (remove) DNA from cells, to cut DNA into smaller pieces, to identify the sequence of bases in a DNA molecule, & to make unlimited copies of DNA

The Tools of Molecular Biology Genetic engineering - making changes in the DNA code of a living organism

The Tools of Molecular Biology Cutting DNA: DNA molecules are too large to be analyzed, so biologists cut them precisely into smaller fragments Restriction enzymes - enzymes that cut DNA at a specific sequence of nucleotides

The Tools of Molecular Biology Separating DNA: Gel electrophoresis - a mixture of DNA fragments is placed at 1 end of a gel, & an electric voltage is applied to the gel When the power is turned on, DNA fragments move toward the + end of the gel Smaller DNA fragments move faster & farther

Gel Electrophoresis

Using the DNA Sequence Cutting & pasting: DNA sequences can be changed Restriction enzymes - used to take a gene from 1 organism & attach it to the DNA of another organism Recombinant DNA - DNA molecules produced by combining DNA from different sources

Using the DNA Sequence Making copies: Polymerase chain reaction (PCR) - technique that allows biologists to make many copies of a particular gene

Cell Transformation During transformation, a cell takes in DNA from the outside (DNA from another organism) That external DNA combines with the cell’s DNA As the cell copies its own DNA, it also copies the external DNA, since the 2 were combined during transformation

Transforming Bacteria Plasmid - circular DNA of bacteria

Applications of Genetic Engineering Genetic engineering makes it possible to transfer DNA sequences, including whole genes, from 1 organism to another It has spurred the growth of biotechnology, a new industry that is changing the way we interact with the living world

Transgenic Organisms Transgenic - organisms have genes from other species A gene from 1 organism can be inserted into cells from another organism Those transformed cells can be used to grow new organisms

Transgenic Organisms Transgenic Animals: They have been used to study genes & improve the food supply Mice have been produced with human genes that make their immune systems similar to ours Livestock have extra copies of human growth hormone

Transgenic Organisms Transgenic Plants: Many crop plants contain genes that produce a natural insecticide Others have genes that allow them to resist weed-killing chemicals Rice has been genetically modified to contain Vitamin A, essential for human health

Cloning Clone - a member of a population of genetically identical cells produced from a single cell

Cloning