Genetic Engineering 13-1 Changing the Living World Selective Breeding

HybridizationInbreedingIncreasing Variation

13-2 Manipulating DNAThe Tools of Molecular BiologyDNA ExtractionCutting DNASeparating DNAUsing the DNA SequenceReading the SequenceCutting and PastingMaking Copies

13-3 Cell TransformationTransforming BacteriaTransforming Plant CellsTransforming Animal Cells

13-4 Applications of Genetic EngineeringTransgenic OrganismsTransgenic MicroorganismsTransgenic AnimalsTransgenic PlantsCloning

Changing the Living World

• Genetic engineering is the alteration of genetic code by artificial means, and is therefore different from traditional selective breeding. Only allowing desired characteristics to reproduce.

• Scorpion poison DNA is located and inserted into cabbage DNA. Cabbage kills caterpillars (insecticide).

Selective breeding

• Hybridization - the act or process of mating organisms of different varieties or species to create a hybrid.

Selective BreedingHybridization cont.

Insecticide resistant cropsHerbicide resistant cropsVitamin enriched crops• Maize streak virus symptoms in a

commercial maize field in Klerksdorp, NorthWest South Africa, showing chlorotic streaking and deformed cob development. This farm grew USA commercial hybrids and experienced almost total yield losses.

Selective Breeding

• Inbreeding-is the continued breeding of individuals with similar characteristics.

Pros- maintains characteristics of the breed

Cons- genetic defects more common

Increasing Variation

• In nature there is a lot of genetic variation found in wild natural populations.

• Breeders can increase variation by inducing mutations.

• Ex. Belgium Blue –myostatin muscle mutation

Increasing Variations with Mutations

• Oil eating bacteria strains created using mutations

Increasing Variation…. with mutations

• Plants have success by introducing more chromosomes (mutation).

• Polyploidy is caused by drugs that double or triple the amount of chromosomes. The effect causes larger and stronger plants.

• Citrus fruits, bananas• Not successful with animals

Manipulating DNA

• Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules. Different techniques are used to extract DNA from Cells.

Manipulating DNA

Different techniques are used to :

• extract DNA from cells• cut DNA into smaller

pieces• identify the sequence

of bases in a DNA molecule

• make unlimited copies of DNA.

The Tools of Molecular Biology

• Genetic Engineering – making changes in the DNA code

• DNA Extraction – The cells are opened and the DNA is separated from the other cell parts.

The Tools of Molecular Biology

Cutting DNA• DNA strands are too long

to work with so scientists use restriction enzymes to cut DNA into fragments, at precise points, on the DNA strand.

• Fits like a “lock and key” when the DNA is opened.

The Tools of Molecular Biology

Separating DNA• How DNA is separated

and analyzed• Gel electrophoresis-

used to compare genomes or gene composition of different organisms or individuals

Using the DNA Sequence

• Once DNA is in a manageable form, it sequence can be read, studied, and even changed. Knowing the DNA sequence allows researchers to study specific genes, to compare them, and to try to discover the functions of different genes and gene combinations.

Using the DNA Sequence

• A chemical dye is added as a marker on bases to help read the DNA sequence before electrophoresis is started.

Using the DNA Sequence

Cutting and Pasting • “Synthetic” sequences can

be joined to “natural” sequences using enzymes that splice DNA together. It’s like taking a gene from one organism and implanting it in another organism.

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

Using the DNA Sequence

Making Copies• Scientists need many

copies of a particular gene to study

• Polymerase Chain Reaction (PCR) is a technique used to make DNA copies.

Cell Transformation

• During transformation, a cell takes in DNA from outside the cell. This external DNA becomes a component of the cell’s DNA.

-ex. Griffith’s experiment, in 1928, proved bacteria could transform DNA

Griffith’s Experiment

Transforming Bacteria• Bacteria can be transformed

using recombinant DNA• Foreign DNA is joined to the

bacteria’s DNA in the Plasmid.• Plasmid’s contain DNA in the

bacteria -contains DNA sequences that

promotes plasmid replication -Plasmid’s contain genetic

markers making it easy to identify transformed bacteria.

Transforming Plant Cells

• Many plants are transformed by using bacteria that insert their DNA into a plant cell to produce tumors

1) Scientists turn off the gene for tumors and insert recombinant DNA into the plasmid. 2) Then the recombinant plasmid can be used to infect plant cells

Transforming Plant Cells cont…

• When plant cell walls are removed, plant cells in culture will sometimes take up DNA on their own.

-DNA can also be injected into some plant cells.

• Tobacco plant cells transformed with reprogrammed virus. Virus makes chromophores to get energy from the sun to be used in solar panels.

Transforming Animal Cells

• Animal cells can be transformed in some of the same ways as plant cells

• Egg cells can be injected w/foreign DNA into the nucleus

• Foreign DNA contains markers for identification by scientists

• Genes can be replaced with new genes

• Great for figuring out the specific functions of genes

Applications of Genetic Engineering

• Genetic engineering makes it possible to transfer DNA sequences, including whole genes, from one organism to another.

-including plants to animals -Enzyme luciferase, gene

fireflys glow, combined with tobacco plant

• Proved that the basic mechanisms of gene expression are shared by plants and animals.

Transgenic Organisms• DNA allows us to construct

organisms that are transgenic.

• Transgenic means that organisms contain genes from other species.

• Transformed cells can create whole new organisms

ex. Glow in dark cats, transgenic salmon compared to regular salmon after one yr.

Transgenic Microorganisms

• Transgenic bacteria used to create important substances useful in health and industry

-reproduce rapidly -easy to grow -cheap ex. Insulin, growth

hormone, clotting factor, Pic- chickens that can’t

pass the bird flu

Transgenic Animals

• Pic – turned off myostatin gene more muscle with-out more food

• Used to study genes and to improve the food supply

• Mice given human genes to mimic our immune systems to study diseases

• Livestock given extra growth hormone to grow faster

• Chickens bacterial resistant to bacteria that cause food poisoning

• Sheep and pigs make human milk (proteins)

Transgenic Plants• Important part of the food supply• Insecticide and herbicide

resistant• Food with more vitamins (Vit.A

rice)• May soon produce -human antibodies that can be used to fight disease -Plastics from plants (maybe)? - Food resistant to rot and spoilage

Cloning

• A clone is a member of a population of genetically identical cells produced from a single cell.

• Bacteria are easy to clone• Multi-cellular organisms

are more difficult to clone• Help save endangered

species• 1997 William Wilmut

cloned Dolly