chapter 13 genetic engineering selective breeding- choosing what parents you want to produce...

Chapter 13 Genetic Engineering

• Selective Breeding- choosing what parents you want to produce offspring for the next generation.

• What do get when you cross a bull dog and a shitzu?

• Hybridization- Crossing dissimilar individuals to bring together the best of both organisms.

• Hybrid Vigor- phenomenon, offspring are better than the parents.

• Inbreeding is the continued breeding of individuals with similar characteristics. – Risky, because it could bring out the

recessive alleles and cause a genetic defect.Blindness, joint problems

Increase Variation

• Why would humans want to increase variations?– Better the species– Make the mutation occur faster– More variety

• http://www.techapps.net/interactives/pepperMoths.swf

Manipulating DNA

• Scientist change DNA by– Extracting DNA from cells– Cut into smaller pieces– Identify the sequence of bases on the DNA

molecule– Make unlimitied copies of DNA

DNA Extraction

• Cells are opened up and DNA is separated from other parts of the cell

Cutting DNA

• DNA is cut into small fragments by restriction enzymes. (Cuts DNA at a specific nucleotide sequence…very precise)

Separating DNA

• Gel Electrophoresis- DNA Fragments are placed in certain gel wells and an electric voltage is passed through them.

• DNA molecules move toward the opposite end of the gel.

• Smaller DNA fragments move faster through the gel.

Using the DNA Sequence

• The DNA Sequence can be read, studied, or changed.

• Compare genes with other organisms.

• Recombinant DNA- produced by combining DNA from different sources.

Making Copies

• In order to study genes, it helps to make copies.

• PCR (Polymerase Chain Reaction)- makes many copies of DNA through a process of heating and cooling using DNA polymerase.

13.4 Applications of Genetic Engineering

• Transgenic Organisms- organisms contain genes from other organisms. – Example: The enzyme (luciferase) from fire

flies was transferred into a tobacco plant cell. – What do you think happens?

• The plant glows at dark…page 331

Why make transgenic organisms?

• Resist pests, herbicides, harsh conditions

• Improve nutritional value, shelf life

• Test and study

• Medical purposes…insulin, growth hormone, clotting factors

• Transgenic Animals can produce more milk, less fat, human proteins

Cloning

• Cloning is producing genetically identical cells from a single cell. – Bacteria is easy to clone (unicellular)– What about multicellular organisms? – Ian Wilmut cloned the first sheep. DOLLY.

Cloning Process

To Clone or Not to Clone?