Post on 17-Dec-2015
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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
Plant Science
Food Science
Genetics
Biochemistry
Statistics
Mathematics
Engineering
Computer Science
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 engineeringGene therapyGene discovery
Human disease genesAlzheimer’s Breast cancer Huntington’s Disease
Plant genesCarotenoid synthesisOil production
Genetics Primer
Gene: basic unit of heredityProtein: product of a geneGenotype: 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
Sugar-phosphate backbone
Bases
DNA is a ladder-like double helix.
Rungs of the ladder are made of pairs of four bases: A, C, G, T
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
proteingene (DNA)expression
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
Genes Proteins Traitsexpression
=
Variation in traits is due to different alleles
Allele 1
Allele 2
Different forms of a gene (called alleles) can lead to different phenotypes (expression of traits)
Gene A Trait (Fruit Color)
Purple
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
GENETIC ENGINEERING
Desired gene
Donor Commercial variety New variety
Desired gene
Desired gene
(cross)
Desired gene Commercial variety New variety
(transfer)
=
=
(many genes transferred)
(one gene transferred)
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 qualityModified oilsDelayed fruit ripeningNutritional 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 are being phased out of
commercial production in favor of varieties 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 17 June 04
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 cloningStrategy:
Good producer
Clones(identical copies)
Interbreed
Medical treatments:Biopharmaceuticals
Biological factors administered as drugsMethods 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
Clotting factor IX
Insulin-like growth factor
Iron supplement ininfant formula
Treatment of hemophilia
Treatment of diabetes
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
Enzymes in plant roots break down (degrade) organic contaminants.
The fragments are incorporated into new plant materials.
contaminant
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.