genetically modified foods vvv
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Genetically Modified Foods
Dr.M.KANNANDepartment of Microbiology,V.H.N.Senthikumara Nadar College,Virudhunagar 626 001
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Have you ever eaten any genetically
modified food?
Can you tell the difference between a
genetically modified organism and a non-GMorganism?
Do GM foods taste any different? Could they?
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Before Reading Any Further
What is the first impression youget when you hear genetically
modified foods?
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Is it
? or
1
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What is a Genetically Modified (GM)
Food?
Foods that contain an added genesequence
Foods that have a deleted gene sequence
Animal products from animals fed GMfeed
Products produced by GM organisms
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Also called genetically modified organisms (GMO). Involves the insertion of DNA from one organism into
another OR modification of an organisms DNA in
order to achieve a desired trait.
+
A strawberry
resistant tofrost=
4 5
Arctic fish DNA strawberry
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What are GMs?
are a result of technology that has altered the
DNA of living organisms (animals, plants or
bacteria)
Other terms that mean the same thing:
Genetically engineered
Transgenic Recombinant DNA (rDNA) technology
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How does this differ from Mendel and his
peas?
GM vs. Selective breading
Selective breading
-slow
-imprecise
-modification of genes that naturally occur in the organism
GM
-very fast
-precise
-can introduce genes into an organism that would not occurnaturally!
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Examples of GMOs
Golden rice rice that contains beta-carotene
(Vitamin A), which is not found in regular rice.
Bt corn corn that contains a chemical
normally found in a bacterium (Bacillus
thuringiensis) that is toxic to insects but not to
humans.
Herbicide resistant plants.
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Common GM Food
GM Food~Plants 10
Tomato Maize
PastaCabbage
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Why produce GM food?
To improve the quality of foodTo improve food production to feed theworld
To strengthen the resistance against herband pests
To cope better with climatic changes
To minimize the cost of production
To minimize loss during transport andstorage
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Why do it?
Rice- not high in essential nutrients
Modification:
+ daffodil genes and a bacterium = beta-carotenecontent drastically increased
+ genes from a french bean = double the ironcontent.
Tomatoes- Introduce genes to increase shelflife.
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Worldwide, 40 % of
our food productiondepends on
irrigation. Depletion
of aquifers isoccurring at twice the
re-charge rate.
Salinization is a major
consequence of
irrigation
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Environmental Hazards from Pesticides
Substantial healthimpacts on workers
Pollution of naturalecosystems/waterways
Loss of insectbiodiversity in agro-ecosystems
Creation of secondarypests
Creation of insectraces resistant to
pesticides
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What is genetic modification?
Does genetic modification only happen in plants?
No, the first gene was transferred into bacteria.
What are some reasons for genetic modification?
Express recombinant insulin in bacteria
What are some of the benefits and some of the
disadvantages of GM foods?
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Many of the same techniques are
used to make a genetic
modifications as to detect one
Polymerase Chain Reaction (PCR) Restriction enzymes
Gel electrophoresis
Transformation
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How is genetic modification
possible?
The components of DNAare the same in all
organisms.
Sequences that code forproteins can be moved
from one organism toanother.
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How can DNA be moved from one organism
to another?
Its quitesimple,
REALLY!!!
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How can DNA be moved from one organism
to another?
Find an organism with the desired
traitIsolate the gene sequence that codesfor the desired trait
Insert the gene sequence into thegenome of the plant cell
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Genetic Engineering
Genetic Engineers can alter
the DNA code of living
organisms.
Selective Breeding
Recombinant DNA
PCR
Gel Electrophoresis
Transgenic Organisms
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Selective Breeding
Breed only those plantsor animals withdesirable traits
People have been usingselective breeding for1000s of years with
farm crops anddomesticated animals.
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Recombinant DNA
The ability to combinethe DNA of oneorganism with the DNAof another organism.
Recombinant DNAtechnology was first
used in the 1970s withbacteria.
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Recombinant Bacteria1. Remove bacterial DNA (plasmid).
2. Cut the Bacterial DNA withrestriction enzymes.
3. Cut the DNA from anotherorganism with restrictionenzymes.
4. Combine the cut pieces of DNAtogether with another enzyme andinsert them into bacteria.
5. Reproduce the recombinantbacteria.
6. The foreign genes will be expressedin the bacteria.
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Restriction Enzymes
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Restriction enzymes are also called restriction
endonucleases They cut double stranded DNA at sequence specific
sites They can produce sticky ends or blunt ends
depending on the enzyme
Sticky Ends
Sticky Ends
Blunt Ends
Blunt Ends
Restriction Enzymes
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1978 Nobel Prize in Medicine was awarded to DanielNathans and Hamilton Smith for the discovery of
restriction endonucleases
Restriction enzymes were discovered in E.colias a defense
mechanism against bacterial viruses (bacteriophages)
The recognition sites are usually 4-12 nucleotides
long
Sequences are palindromic (GAATTC)
There are hundreds of restriction enzymes currently
being used
Restriction Enzymes
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Restriction Enzymes
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Polymerase Chain Reaction
PCR
PCR allows scientists tomake many copies of apiece of DNA.
1. Heat the DNA so itunzips.
2. Add the complementarynitrogenous bases.
3. Allow DNA to cool so thecomplementary strandscan zip together.
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Invented in 1983 by Kary Mullis (Nobel Prize in 1993for its discovery)
Uses primers to exponentially amplify a specificregion of DNA
Components needed for the reaction: DNA
Primers to region of interest
DNA polymerase (Taq used to synthesize the DNA) dNTPS (the building blocks of the copied DNA)
Buffer (with appropriate salts to ensure the enzyme worksproperly)
PCR
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Three steps of the reaction: Denaturation: High heat (94-98o) to separate the strands of
DNA
Annealing: (50-60o depends on the primers) this step
allows the primers to bind to the denatured DNA strands Elongation (74o) DNA polymerase synthesizes the new
strand
This step is dependant on the length of the product to beamplified (1min/1kb of DNA)
Check products with gel electrophoresis andsequencing
PCR
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PCR: Cycles
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PCR: Thermocycler
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Gel Electrophoresis
This technology allows
scientists to identify
someones DNA!
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Steps Involved in Gel Electrophoresis
1. Cut DNA sample withrestriction enzymes.
2. Run the DNA fragments througha gel.
3. Bands will form in the gel.
4. Everyones DNA bands are uniqueand can be used to identify a
person.
5. DNA bands are like geneticfingerprints.
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Gel Electrophoresis
Gel electrophoresis is used to separate nucleicacids (DNA and RNA) or proteins for analytical use
DNA and RNA are separated using agarose
Proteins are separated using polyacrylamide
The gel is a matrix (cross-linked polymers) that allowproducts to be separated
Separation is based on the size (based on charge)of a product as it moves through a charged field
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Gel Electrophoresis
The negative charge is at the top (closest tothe samples) and the positive charge is at thebottom
Samples are negatively charged and will travel
towards the positive charge DNA and RNA are negative because of their sugar-
phosphate backbone
Proteins are denatured to give a constant shape and
given a charge through the negative loading bufferused
Samples are diluted in a loading buffer thathelps the samples stay in the wells
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Gel Electrophoresis
Applications
Separating restriction digests
Analyzing/purifying PCR products Sequencing
Protein analysis
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Gel Electrophoresis
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Gel Electrophoresis
Sample agarose gel stained with ethidium bromide (EtBr)
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How are animals targeted?
The microinjection
method uses a fine
needle to inject asolution of DNA into a
developing embryo.6
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How are plants targeted?
A particle gun is used to shoot
small bits of metal coated with
the gene into the plant.
Agrobacterium that normally normallyinfects plants with disease is used to infectplant with gene of interests or
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The DNA of plants and animals
can also be altered.
PLANTS
1. disease-resistant andinsect-resistant crops
2. Hardier fruit
3. 70-75% of food insupermarket is geneticallymodified.
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How to Create a Genetically
Modified Plant
1.Create recombinantbacteria with desiredgene.
2. Allow the bacteria toinfect" the plant cells.
3. Desired gene is insertedinto plantchromosomes.
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How is this done?: Transgenic tomatoes
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What do you think about eating genetically
modified foods?
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Genetically modified organisms are called
transgenic organisms.
TRANSGENIC ANIMALS
1. Mice used to study humanimmune system
2. Chickens more resistant toinfections
3. Cows increase milk supply andleaner meat
4. Goats, sheep and pigs producehuman proteins in their milk
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Human DNA ina Goat Cell
This goat contains a humangene that codes for a bloodclotting agent. The bloodclotting agent can be harvestedin the goats milk.
.
Transgenic Goat
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Desired DNA
isadded to an
egg cell.
How to Create a Transgenic Animal
Molecular agriculture makes new gene combinations possible
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Molecular agriculture makes new gene combinations possible
Peas (on the left) that make a genetically engineeredbean protein are insect-resistant and do not need tobe sprayed with pesticides.
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Ha Ha Ha!
d
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Genetic Engineering and
Crime Scenes
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Roundup Ready Gene
The glyphosate resistance gene protects food plantsagainst the broad-spectrum herbicide Roundup,which efficiently kills invasive weeds in thefield. The major advantages of the "Roundup
Ready system include better weed control,reduction of crop injury, higher yield, and lowerenvironmental impact than traditional weed controlsystems. Notably, fields treated with Roundup
require less tilling; this preserves soil fertility bylessening soil run-off and oxidation.
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Herbicide Resistance
Herbicides, like glyphosate and glufosinate, areused to eliminate weeds to maintain nutrientcontent in the soil but they decrease the yield.
Scientists insert the herbicide resistance genes viaagrobacterium into food plants so that they willnot be affected by the herbicide.
This reduces the excessive use of herbicide.
GM Food~Plants 53
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Pest resistance
Scientists insert the toxin producing gene fromBacillus thuringienus, a kind of soil bacterium,into maize.
Destructive insects will be killed when eating thecrop.
The loss due to destructive insects is greatly
reduced.
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Other applications
Potato - modified to produce a beetle killing toxin Yellow squash modified to contain to viral genes
that resistant the most common viral diseases
Develop foods that contain vaccines and antibodies
that offer valuable protection against diseases suchas cholera, hepatitis, and malaria
Canola modified to resist one type of herbicide orpesticide
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GM CanolaCanadian-Australian Relations
Bayer CropScience produces genetically modified canola in Australia for
the Canadian market. It is produced to resist the herbicide Liberty and can
yield up to 20% higher than conventional canola.
B fit f G ti E i i
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Benefits of Genetic Engineering
and Modifying
1. Higher yielding crops, more efficient use of land
2. Can save money and promote higher profits
3. Longer shelf life, less wasteExample// Tomatoes from genetically
modified seeds stay fresh
longer.
4. Enhanced taste and quality
5. Reduced maturation time
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Importance of GM crops
Worldwide, 9 percent theglobal primary crop
production from genetically
modified crops
2006: over 100 millionhectares in 22 countries
64% of total soya crop and
24% of the global maize
crop
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Importance (2)
Many processed foods
contain Soybean oil
and/or glucose syrup
(from corn)
Difficult to avoid food
containing genetically
modified material,
especially in the USA
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Animal feeds
Likewise animal feeds
commonly contain corn
and soybean meal from
GM crops
Also in Europe GM
material was found in
milk and meat
Some GM crops will improve the
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Some GM crops will improve the
nutritional quality of foods. Such foods are
now in the pipeline.
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Labels are not neutral!
Produced by
RadiationBreeding!
Truthful labels can be misleading or meaningless
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There are no GM apples anywhere!
Is food labeled this waynutritious?
Truthful labels can be misleading or meaningless
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How to Label?
Conventionallygrown
GMO
Pesticides, twice a week Pesticide free
Should foods from GM crops be labeled?
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Should foods from GM crops be labeled?
Perhaps!
The US takes the view that if
foods are substantially equivalent,the method of producing them
need not be on the label.
Farmers use a variety of techniques, and keeping
production streams separate from plow to platecosts money. Such separation is called identity
preservation. Who should pay for this?
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How common are GM foods?
48 foods have
been
approved for
use by the
Canadian
Food
InspectionAgency.
ProductsCornCanola
PotatoesTomatoesSquashSoybeans
FlaxCottonseedoilSugarbeets
Derived
Products
Corn syrupTofuCanned foodsSoya sauceAnimals that
feed onGMOs.AND MORE
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How common are GMO foods?
Labeling of GM foods is not mandatory unless ifthereis a health or safety concern (Health Canada/CanadianFood Inspection Agency)
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Who Uses this technology
The Countries that Grow 99% of the
World's Transgenic Crops
69%
23%
7% 1%
USA
Argentina
Canada
China
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Potential Environmental Hazards
Reduced
effectiveness of
pesticides as insects
become resistant toengineered toxins.
Loss of biodiversity
Harm to other organismsPollen from Bt corn was shown to
cause high mortality rates inmonarch butterfly larvae(9). BUT
follow-up studies have shown
that the exposure levels in thefields are negligible(10).
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Potential Environmental Hazards
Gene Transfer to non-target species
Herbicide resistant plants and weeds could cross
breed and create superweeds
To address this one could: Create sterile male plants that dont produce pollen
Engineer the plants so that pollen doesnt contain the
foreign genes
Create buffer zones of non-GM crops around GM
crops. The buffer crops would not be harvested.
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Potential Human Health Risks
Allergens
Genetic engineering could potential introduce or create
allergens
For example, inserting genes from a nut into another
plant could be dangerous for people who are allergic to
nuts
Unknown health risks
Biological processes involve a lot of INTERACTIONS It is often difficult to identify every possible interaction.
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Economic Hazards
Elimination of competition
GM seeds are patented
Suicide seeds
Plants with sterile seeds that are infertile are
created
Farmers are forced to buy seeds every year
However, some companies have reduced costsor donated GM seeds to impoverished nations.
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Creating a balance
So are GM foods a
good or bad thing?
It depend on each
individual case.
Consumers, the
government and
scientists should be
responsible for
weighing thebenefits against the
costs.
Improved Nutrition
Resistance todisease
Reduced use ofchemicals
Environmental risks
Health risks
Economic risks
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Religion and choice?
What happens if vegetarians eat food whichis genetically engineered with an animal gene?
Will it repel choice of food?
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Solutions
Add labels to the packages
Improve genetic modification technology
Food tests
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Concern: Food Safety
GM food is not labeled as such The industry argues GM crops
are substantially equivalent
to their conventional
counterparts Consequently no need for
special considerations
concerning safety
Label GMO free opposed
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Risks with GM continued:
Biodiversity
Addition of Bt gene into plants including corn, potatoes andcotton to increase resistance to plants
Bt gene obtained from Bacillus thuringiensis (a soil bacteriumthat produces a natural insecticide)
Problem: plants producing Bt toxin are releasing toxin inpollen
Draper, D. (2002). Our Environment: A Canadian Perspective 2nd Ed. Scarborough: Thompson Canada Lmt.
Pollen from a Bt plant was dusted on to milkweed:
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Pollen from a Bt plant was dusted on to milkweed:
- only 56% of young monarch butterfly larvae lived
- whereas pollen from organic plants dusted on the
milkweed produced a survival rate of 100%.Approximately half of the monarch butterflypopulation live in the corn belt of the USA
= this new gene could have serious repercussions for
this organism