13 genetic engineering bw

Genetic Engineering

- Archeological evidence shows that humans began cultivating plants and animals for food about 10,000 years ago

- Specific organisms were bred to improve future generations

- Simple form of applied genetics

CONTROLLED BREEDING

Manipulates the characteristics of the off spring by selecting parents

with specific phenotypic traits

Types of Controlled Breeding

1. Selective BreedingProcess of choosing a few individuals to serve

as parents for next generation

- Luther Burbank: Californian plant breeder (early 1900s)

- responsible for 800 new plant varietiesEx: seedless grape

Spineless cactusBurbank potatoDaisies

- Corn: bred for 7000 years- Small horses, dogs, cats: bred for different

breeds

Types of Controlled Breeding

2. Inbreeding

Process of crossing individuals with similar characteristics so those characteristics appear in offspring

- purpose: to maintain or intensify desireable traits

- individuals closely related (same species)

- more risk of passing recessive genetic defects

ex: poodles: joint deformities maine coon cats: heart murmurs

Types of Controlled Breeding3. Hybridization

Process of crossing individuals of different but related species

- produces hybrids

- hybrid vigor: offspring are hardier than parents

(grow faster, larger, and are healthier)

Ex: cattle - disease resistant corn – yield 10 times more than old

varieties

broccoflower liger zonkey leopon tangelo

Types of Controlled Breeding4. Induced Mutations (1927)

Polyploidy: common in plants, deadly in animals

- plants treated with chemicals to prevents cell plates

- resulting cells have multiple sets of chromosomes

- results in larger fruit and vegetables

• Techniques were forerunners modern genetic engineering

• Today geneticists engineer changes directly into an organismsDNA

GENETIC ENGINEERING (GENE SPLICING/GENE

CLONING)

• Process of direct gene manipulation

• Goal: to introduce new characteristics into organisms to increase its usefulness

• Basic steps of genetic engineering involve:1. isolation of gene2. manipulation of gene/cloning gene -PCR3. reintroduction of DNA into model organisms

animation: steps in cloning a gene

Genetic Engineering TechniquesI. Making Recombinant DNA

1. Restriction enzymes cut DNA into fragments that can be isolated and separated

- very specific proteins, recognizes and cuts DNA at specific sequence into pieces

Ex: EcoRI – cuts DNA whenever C-T-T-A-A-G sequence occurs

2. Production of recombinant DNA

- DNA composed of fragments of DNA segments from at least two different organisms

- restriction enzymes cut bacterial plasmids (extra circular DNA molecules in bacteria)

- plasmids have “sticky ends” (unpaired bases)

- original DNA is attached to plasmid sticky ends

Genetic Engineering Techniques

3. reintroduction of DNA into bacterial vector

- recombinant DNA taken up with bacterial

DNA and now produced by bacterial cell

- recombinant DNA is isolated and CLONED

- PCR (polymerase chain reaction) induced

- purpose: to make 1000s of recombinant plasmids

PCR animation

4.DNA sequencing

- Process of reading exact order of bases in fragment of DNA

- makes it possible for scientists to make sure gene of interest has been cloned

rDNA: animation

Genetic Engineering Techniques

II. Microinjection - Process of injecting genetic material containing the new gene into the recipient cell

- direct gene transfer, no use of vectors

- in large cells done with fine tipped glass needle

- somehow injected genes find the host cell genes and incorporate themselves among them

Ex: most common method of making genetically altered mice

Genetic Engineering Techniques

III. Bioballistics

- projectile methods that use metal slivers to deliver the genetic material to the interior of the cell.

- small slivers coated with genetic material

- once in the cell, genetic material is transported to nucleus where it is incorporated among the host genes

IV. Electro and Chemical Poration

- process that creates pores or holes in the cell membrane to allow direct entry of new genes

- done by bathing cells in solutions of special chemicals or weak electric current

TRANSGENIC ORGANISMS /GENETICALLY MODIFIED

ORGANISMS (GMO’s)

• organisms that contain foreign genes

TransgenesisThe use of recombinant DNA techniques to introduce new characters (ie. genes) into organisms (including humans) that were not present previously.

Types GMO’sI. Bacteria

-human DNA inserted in bacterial plasmid

-recombinant produces large volumes of proteins

Ex: human growth hormone (HGH), insulin

Types GMO’sII. Plants

- 1986: Howell - inserted gene to producer enzyme luciferase (fireflies)into tobacco plant

- enzyme in fireflies

- only produces enzyme in conditions without light

(gene expression)

- cloned cells reproduced tobacco plant that

glowed in the dark

Making Transgenic Crops

Steps

1. extracting DNA

2. cloning a gene of interest

3. designing the gene for plant infiltration

4. transformation

5. plant breeding

Other Transgenic PlantsBT corn (bacillus thuringiensis)

Soil bacterium that resists insecticidal toxins: makes corn resistant to pests and less need for pesticides

Other Transgenic Plants

Calgene tomato “Flavr Savr”

stays fresh longer because enzyme to break down pectin are reduced by genetic alteration

Types GMO’sIII. Animals

Transgenic sheep:

human gene for milk production inserted into sheep and now produces proteins of human milk

Oncomice (cancer mice)

Used in medical research to find cures for cancer

Other examples of transgenic animals:

Transgenic chickens: - grow faster and larger in close quarters - produce more protein in their egg whites- produce human protein drugs in their eggs

Transgenic pigs: - produced by fertilizing normal eggs with sperm cells that have incorporated foreign DNA

- may someday be able to produce transgenic pigs that can serve as a source of transplanted

organs for humans

video

Cloning Animals 1997 Wilmut (Scottish)

- cloned sheep “Dolly”

- process: nucleus of egg is replaced with nucleus of adult , resultant organism identical to adult

- now companies are making

cloning available to pet owners for

their beloved pets who die

- is this ethical?

Genetic Savings and Clone

Ethics of GMOs and Cloning

• Imagine cloning humans to make armies.

• Could clones and GMOs be patented?

• Are genetically modified livestock and agriculture harmful?

• Would only perfect genetically engineered infants be desirable.

APPLICATIONS OF G.E. The first genetic fingerprint 1984

Electrophoresis Animation Detail

1. DNA Fingerprinting (used in forensics)

Process of identifying and distinguishing DNA of individuals

- each person has unique repeat sequences and numbers of

non coding introns

- sample is taken and DNA is extracted

- fragments of repeats of introns are labeled and put into a gel electrophoresis where they separate

- create banding patterns which are unique for every human

APPLICATIONS OF G.E.- Once banding patterns are apparent they are transferred

to a Southern Blot for identification

Southern blot animation

Applications of Genetic EngineeringDNA Fingerprinting

Applications of Genetic EngineeringDNA Fingerprinting

Restriction fragment length polymorphisms

Applications of Genetic EngineeringDNA Fingerprinting

APPLICATIONS OF G.E.Microarray

APPLICATIONS OF G.E.2. Gene therapy

Creating transgenic humans to erase genetic diseases

- recombinant DNA put directly into human cells or through virus vectors

APPLICATIONS OF G.E. 3. Pollution control

- genetically altered bacteria used to decompose garbage

sewage, and petroleum products

Unlike the left tower, which uses chemicals, the tower on the right at this wastewater-treatment plant now uses bacteria-covered foam blocks (inset) to eliminate the hydrogen sulfide bubbling from treated sewage.

Deshusses/PNAS

APPLICATIONS OF G.E.

4. Medicines and Vaccines produced by bacteria and viruses

- E coli: used to make human insulin

- hamster cell cultures: used to make TPA (tissue plasminogen activator)- dissolves blood clots in heart attacks

- EPO (erythropoiten): increases red blood cell production

- interferon: fights viral infections, increases immunity

- vaccines

vaccine animation

APPLICATIONS OF G.E.

5. Agriculture and livestock

- hardier, disease and environmentally resistant fruits and vegetables

- larger sturdier animals

HUMAN GENOME PROJECT

• begun in 1990: coordinated by US Dept of Energy and NIH

• purpose: - to identify the 20-25,000 genes in human DNA

- to determine sequences of 3 billion DNA base pairs

- to license info to biotech companies to foster new medical applications

• international: US, England, China, France, Germany, Japan

• used combined genomes of anonymous small number of people

Study for the test !