Genetically Modified Organisms

Chapter 15 (ibook)

GMO: Genetically Modified Organism

• GMO: organism whose genome has been engineered in the laboratory in order to favour the expression of desired physiological traits or the production of desired biological products.

• NY Times – Genetically Modified Food Navigator

• Britannica article • Britannica GMO background

More New Vocab

• Biotechnology – process of manipulating organisms, cells, or molecules to produce a specific products.

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

• Transgenic organism – containing genes from another species • host that carries the inserted DNA from one or more organisms = genetically

modified organism

Genetic Engineering/Modification

• Selective Breeding (hybridization vs. inbreeding)• Ex: dog breeds• 1849 -1926 Luther Burbank (botanist) developed more than

800 varieties of plants via hybridization

Hybridization – crossing dissimilar individuals to bring together the best of both.Inbreeding – maintains desirable characteristics in a line of organisms

• Associated risk: increase chance that a cross will bring together 2 recessive alleles for genetic defect.

Fig. 12.11, p. 273

Crop

Cross breeding

Desired trait(color)

ApplePear

Offspring

Cross breeding

Best results

Newoffspring

Desiredresult

Biotech Crops in the United States [from Wikipedia]

Fig. 9-10 here

The Objectives of Genomics

• Disease resistance• Drought tolerance• Frost tolerance• Salt tolerance• Improved nutritional value• Incorporate human vaccines

The Problems with Genomics

• Environmental concerns• Not considered safe by all consumers • Not affordable in all countries• Major player in the future of agriculture• Might keep food production in pace with

population growth

Environmental Problems

• Pest resistance to genetically engineered toxin

• Broad spectrum impact on non-target species

• “Super weeds”

• Contamination (decreasing natural variation)

Food Safety Issues

• Proteins cause allergic responses

• Antibiotic resistance to human pathogens

• Plant produces new toxic substances

Summary: GMF Controversy• Unexpected plant mutations create higher toxin levels• Introduce new allergens into foods• Lower nutritional value• Don’t help feed world’s hungry• Reduce effectiveness of natural pesticides• Resistant genes passed on through pollination to wild relatives =

super weeds• Increased herbicide use on resistant crops• Increased costs of food to cover devp. & patenting of GMF• Rapid evolution of pesticide resistant insects.• Killing beneficial insects – monarch butterfly• Introducing chemicals into soil killing soil organisms• Irreversible and unpredictable genetic & ecological effects

Polymerase Chain Reaction

• Amplifies a selected section of DNA quickly – Provides LOTS of DNA to

work with and analyze

• PCR animation

• PCR tutorial

• PCR song

35S Promoter Gene

• This is a “marker” found in many GMO’s– from cauliflower mosaic virus; allows modified

genes to enter original modified plant cells

• Wild Type : no marker = (-)• Round-Up Ready: yes marker = (+)• Your food sample:

– (-) result = not a GMO– (+) result = yes a GMO!

Tubulin Protein

• Plant protein found in all plants, therefore, the gene for this protein should be found in all plant DNA samples.

• (-) Your sample is missing plant DNA!

• (+) Your sample contains captured plant DNA!

Results you should get:

• Wild Type Soy Bean:(-) 35s

(+) Tubulin

• Round-Up Ready Soy Bean:

(+) 35 s

(+) Tubulin

• Your Food Item:

(???) 35s

(+) Tubulin unless your food is really over-processed!

Gel Electrophoresis• Physically separate different sized

fragments through an agarose gel using an electrical current

• Tutorial 1 • Tutorial 2 - Work through 4 Discovery Modules

• Tutorial 3- Go to “Manipulation” then “techniques” then “sorting and sequencing”