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