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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