Transcript Finally…Genetically Modified Food

Genetically Modified Food
Plan for Today
•Quick foot-and-mouth disease trivia
•Let’s talk about our survey results
•Some background on genetically modified food
A question from last time
Foot-and-mouth (or hoof-and-mouth) disease
• Caused by a virus that affects hoofed animals (cows, pigs, sheep, etc)
– Causes blisters on the mouths and feet of infected animals, fever, lack of
appetite, shivering, lack of milk production
– Spreads quickly in a herd through direct contact, through the air, and via
shoes/tires
– Animals recover in 2-3 weeks, but are usually destroyed before then so don’t
transmit disease to other animals
• Rarely transmitted to humans (and only causes flu-like symptoms in
humans)
• No vaccine because virus mutates quickly and is cheaper to deal with
outbreaks than pay for immunization
Your assignment from Monday!
Tally your responses to each question and write the numbers on the
board:
1)
2)
How effective are antibiotics at fighting colds?
Have you ever taken an antibiotic at a time when you were not
prescribed to do so by a doctor?
3)
Do you use antibacterial soap?
4)
Is it possible for a disease to become resistant to antibiotics?
5)
Is it possible for a human being to become resistant to
antibiotics?
6)
Did you know that many farmers (particularly fruit growers)
treat their crops with antibiotics? Do you know why they do that?
• Are most people well-educated about
antibiotics and antibacterial soap?
• Are you surprised by the results?
• What are some practical implications of
these results?
And now…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
And now…genetically modified foods
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
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
• How it works: Propagate selected DNA through bacteria
propagation
– Cut & splice plant genes and then propagate in bacteria
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????
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!
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
GM Statistics
• In 2001, 6% of total world agriculture was
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
Questions for you
• Are the benefits of golden rice, siberian tomatoes,
B.t. corn, and the banana vaccine 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?