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Genetics and Biotechnology
Biotechnology
A group of many technologies that use
living cells or their processes to make
products or solve problems
Used in basic and applied research
Used in developing products for the
marketplace
Fields Contributing to Biotechnology
Medicine
Statistics
Plant Science
Mathematics
Food Science
Engineering
Genetics
Computer Science
Biochemistry
Philosophy (Ethics)
Applications of Biotechnology
Cloning
Genes
Whole organisms
Drug production
Insulin
Disease prevention
HIV test
Blood-type test
Pregnancy test
Applications of Biotechnology
Genetic engineering
Gene therapy
Gene discovery
Human disease genes
Alzheimer’s
Breast cancer
Huntington’s Disease
Plant genes
Carotenoid synthesis
Oil production
Genetics Primer
Gene: basic unit of heredity
Protein: product of a gene
Genotype: genetic makeup of an
individual (sum of all the genes)
Phenotype: observed traits of an
individual, due to expression of its genes
and interaction with the environment
Genes are made of DNA
Cell
Nucleus
DNA is a ladder-like double
helix.
Rungs of the ladder are
made of pairs of four bases:
A, C, G, T
Sugar-phosphate backbone
Bases
Genes code for proteins
The sequence of bases in the DNA of a gene
contains information to make a protein
The DNA code is triplet
Each triplet codes for an amino acid
Example: the sequence TTG is the code for the amino acid
tryptophan
Proteins are built from amino acids
Transferring the information from DNA to protein
is called gene expression
gene (DNA)
expression
protein
Gene expression is regulated
The same set of genes is contained in (nearly)
every cell of an organism, but...
Not all genes are expressed in every cell
Genes for helping plants absorb minerals from the
soil are expressed in the root
Genes for plant oil production are expressed
primarily in the embryo
Genes for milk production in mammals are
expressed in the mammary glands
Proteins have many functions
Transport:
hemoglobin carries oxygen in blood
Structural:
collagen holds cells together
Receptor:
receives signals sent to cell
Regulatory:
control gene expression
Enzymes:
catalyze chemical reactions in the cell
Proteins govern traits
An organism’s appearance and qualities are
the products of gene expression
expression
Genes
Proteins
=
Traits
Variation in traits is due to different alleles
Different forms of a gene (called alleles)
can lead to different phenotypes (expression of traits)
Gene A
Trait (Fruit Color)
Allele 1
Purple
Allele 2
White
Transmitting genes to offspring
Traditional mating or breeding
Female contributes half her genes through egg
Male contributes half his genes through sperm
Offspring have half their genes from mom and half
from dad
Genetic engineering
Donor contributes one or a few genes
Offspring have all their own genes plus one or a few
genes
“Breeding” vs. “Engineering”
TRADITIONAL BREEDING
Donor
Commercial variety
New variety
(many genes transferred)
=
(cross)
Desired gene
Desired gene
GENETIC ENGINEERING
Commercial variety
Desired gene
New variety
(one gene transferred)
=
(transfer)
Desired gene
Terms
Transgenic organism
One in which a gene has been introduced or
modified by genetic engineering
Genetically engineered organism (GEO)
Same as transgenic organism
Genetically modified organism (GMO)
Erroneously assumed to be same as transgenic
organism
Actually, organisms can be modified genetically by
“breeding” or by “engineering”
Applications of Biotechnology
Agricultural food production
Improved production
Disease resistance
Herbicide tolerance
Insect resistance
Improved food quality
Modified oils
Delayed fruit ripening
Nutritional enhancement
Insect resistance: Bt corn
Plants contain a gene from the soil bacterium,
Bacillus thuringensis
Bacillus thuringensis strains contain genes for a
series of proteins called Bt toxins
Bt toxins:
are toxic to certain insects, including European corn
borer
break down rapidly in the soil
are not harmful to mammals or birds
Concerns
Environmental concerns
Effect of Bt corn on monarchs
Invasion of natural plant
populations by genetically
engineered crops
Food safety concerns
StarLink in taco shells
Farmer’s point of view
Impact of Bt corn on monarch butterflies
In 1999, an article* was published stating that
pollen from Bt corn plants could kill monarch
butterfly larvae
Assertion: planting of Bt corn poses a risk to
monarch butterflies
Concerns were raised and more research was
done
*
Losey et al., 1999. Transgenic pollen harms monarch
larvae. Nature 399:214.
Questions asked
Are the data
reproducible?
Does the lab represent
the field?
What controls should
be included?
What does monarch
reproductive behavior
say about the lab
experiment?
Is all Bt corn the same?
How does Bt corn
compare to impact of
current insect control
methods?
What is the greatest
documented threat to
monarch survival?
Is the monarch
endangered?
Findings
Some varieties of Bt corn produce pollen with
toxic levels of Bt; these have been phased out
of commercial production in favor of varieties
that do not produce Bt in the pollen
In most parts of the country where corn is
grown, the time of monarch larvae feeding does
not coincide with the time that corn pollen is
shedding.
More Findings
Pollen does not accumulate on the same leaves
as monarchs lay their eggs, even when
milkweed plants (preferred host) are found in
corn fields
The greatest threat to monarchs is predation.
Overall conclusion: Bt corn does not pose a
significant risk to monarch butterflies
Gatehouse et al., 2002. The case of the monarch
butterfly: a verdict is returned. Trends in Genetics
18:249-251.
The taco shell controversy
A variety of Bt corn called StarLink was detected
in taco shells and other foods
StarLink produces a variety of Bt toxin that had
not been tested for allergenicity in humans
Therefore, StarLink was approved by FDA only
for animal feed and not for human consumption
http://www.cbsnews.com/stories/2000/09/18/tech/main234240.shtml;
accessed 10 June 05
Risks to natural plant populations
Survival / reproduction of genetically engineered
crops outside cultivation
Pollen flow of genetically engineered crop to
wild relatives, hybrid formation, survival and
reproduction
Spread and persistence represent possible
economic or environmental harm
Wolfenberger and Phifer, 2000. The ecological risks and benefits of genetically
engineered plants. Science 290:2088.
Farmer’s view
45% of farmers had higher yields in fields of Bt
corn than conventional corn in 1998
Nearly 26% of farmers using Bt corn reported a
decrease in pesticide use
Even considering additional cost of planting Bt
corn (~$15/acre), Bt corn should pay off in 7 out
of 10 years
Bt corn can also reduce occurrence of Fusarium
ear rot (spread by borers)
Applications of Biotechnology
Agricultural food production
Plants
Animals
Medical treatment
Biopharmaceuticals
Gene therapy
Environmental detoxification
Bioremediation
Phytoremediation
Animal production
Improving production through cloning
Strategy:
Good producer
Clones
(identical copies)
Interbreed
Cloned Animals
Dolly and Mom
Calf Clones
Medical treatments:
Biopharmaceuticals
Biological factors administered as drugs
Methods of production
purification from animals
purification from genetically
engineered organisms
Examples
insulin, for diabetes
human growth hormone, for genetic deficiencies
clotting factors for types of hemophilia
Using animals for pharmaceuticals:
Molecular “pharming”
Proteins from milk of transgenic animals
Lactoferrin
Iron supplement in
infant formula
Clotting factor IX
Treatment of hemophilia
Insulin-like growth factor
Treatment of diabetes
Medical treatments:
Gene therapy
David Vetter, the “Bubble Boy”
Severe Combined Immune Deficiency
Applications of Biotechnology
Agricultural food production
Plants
Animals
Medical treatment
Biopharmaceuticals
Gene therapy
Environmental detoxification
Bioremediation by bacteria
Phytoremediation by plants
Environmental detoxification:
Phytoremediation
Types of contaminants detoxified
heavy metals
radionuclides
organic compounds
petroleum products
explosives
Mechanisms plants use to detoxify
Accumulating heavy metals
Breaking down organic compounds
Volatilizing organic compounds
Phytodegradation
contaminant
Enzymes in plant roots break down (degrade) organic
contaminants.
The fragments are incorporated into new plant materials.
Phytoaccumulation
Nickel is removed from soil by moving into plant roots,
stems, and leaves.
Plant is then harvested and disposed of, and site is
replanted until nickel levels are acceptably low.
Genetics and Biotechnology