Transcript Finally…Genetically Modified Food

Genetically Modified Food
Genetically Modified Foods
Which of the following does not qualify as a
genetically modified food?
A)
B)
C)
D)
E)
Angus cattle
Guernsey dairy cows
Rhode Island red chickens
Broccoli
Corn
F) None of the above!
There are almost no foods you eat that come from
naturally occurring species
Farmers have been selectively breeding, crosspollinating, etc. for thousands of years
Basic Genetics
• Dominant & Recessive Genes
• Someone might express a dominant gene
but carry a recessive gene
• Recessive genes from both sides can appear
in subsequent generations
• Plants (or animals or people) can be
modified by selecting for desirable traits
Plant Breeding by Trial & Error
• Natural Selection – Darwin
• Artificial Selection
– Used for millennia for crop improvement
– Select best product for future use
• Artificial selection has led to much more
profitable and edible crops
– Higher food to waste ratio
– Land produces higher yields
Modern Plant Breeding
• Gregor Mendel’s laws of inheritance 1857 – peas (tall,
short, smooth, wrinkled, etc.)
• Mendel’s theories accepted ~ 1900
• Crossing plants with thousands of genes (45,000 – 56,000
genes in rice)
• Improves crop yield but undetermined consequences
because of large number of genes involved
• Improves edibility of crops – break down plant’s natural
defenses against predators (chemicals which may be toxic
or allergenic to humans)
Plant Genetic Modification (GM)
• Introduce gene or genes artificially
• Plants can be described as “transgenic”
• Began in late 1970s – development of DNA
manipulation
• Gained knowledge of how to cut DNA
molecules at particular points and glue back
together – recombinant DNA technology
GM Process
• Propagate selected DNA through bacteria
propagation
• Cut & splice plant genes into plasmids and then
propagate in Escherichia coli (human gut
bacterium)
• Used to modify plant characteristics – higher
yield, more edible, disease resistant, pest resistant,
etc.
• First used in pharmaceutical industry to make
recombinant human insulin – approved by FDA in
1981
Genetic Modification of the Potato
Genetically Modified Crops, Nigel Halford, 2003
Advantages of GM
• Precision – involve only individual genes that are
desirable
• Genes can act on only a specific part of plant or a
particular portion of its life cycle
• Safety of protein produced by gene can be studied
prior to use in GM program
• Improved crop yields
• Improved crop characteristics
• Reduce pesticide use – insect resistant and/or
herbicide resistant crops
Disadvantages of GM
• Invest more time & money than program of
random mutations
• Barriers and restrictions to GM crop
development – regulations in some
countries
• Safety????
GM Statistics
• In 2001, 6% of total world agriculture were
GM crops
• > 50% of world’s soybean crop is
genetically modified
• Countries growing GM crops: US, Canada,
Argentina, Uruguay, Mexico, Spain,
Bulgaria, Ukraine, Romania, China, South
Africa, Australia
Golden Rice
The vitamin A-producing gene is taken out of
a red pepper and put into rice
Advantage: Could save millions of children
world-wide from blindness
Siberian Tomatoes (Strawberries, too)
The anti-freeze-producing gene is taken out of a
flounder and put into tomatoes
Advantage: Tomatoes that can be shipped at
lower temperatures, less rotting, less waste, and
more profit for tomato growers
B.t. Corn
An insecticidal protein from
the bacteria Bacillus
thuringiensis is put into
corn
Advantage: Corn is
protected from pests, so
chemical pesticides are not
necessary
In development: Banana Vaccine
Viral proteins for infectious diseases such as
Hepatitis B will be put into bananas
Advantage: Ability to efficiently vaccinate
people world-wide
Potential Safety Concerns
1. Pleiotropy: genes have multiple functions,
especially when they work in conjunction with
other genes

We may transfer genes that have other
functions we don’t want
 The genes may develop new functions when
they interact with a new genome
Potential Safety Concerns
2. Plasmids: functions (especially undesirable
ones) may transfer to other organisms in the
environment
3. Pollination: When plants spread seeds, other
farms could pick up transgenic traits without
realizing it
Potential Safety Concerns
Since transgenic foods haven’t been around
long, nobody can study the long-term effects of
eating these foods yet
And these are just the safety issues–there’s a lot
more to consider!
Questions for you
• Are the benefits of golden rice worth the risks?
Why or why not?
• Are the benefits of Siberian tomatoes worth the
risks? Why or why not?
• How do you decide what type of genetically
modified food is worth the risk of eating?
• The EU currently bans the importation of live
genetically modified plants but does import
genetically modified foods. Is this good policy?