Genetics and Biotechnology

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Genetics and Biotechnology
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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

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Fields Contributing to Biotechnology

• Medicine
• Plant Science
• Food Science
• Genetics
• Biochemistry

• Statistics
• Mathematics
• Engineering
• Computer Science
• Philosophy (Ethics)

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Applications of Biotechnology

• Cloning
• Genes
• Whole organisms
• Drug production
• Insulin
• Disease prevention
• HIV test
• Blood-type test
• Pregnancy test

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Applications of Biotechnology

• Genetic engineering
• Gene therapy
• Gene discovery
• Human disease genes
• Alzheimers
• Breast cancer
• Huntingtons Disease
• Plant genes
• Carotenoid synthesis
• Oil production

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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

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Genes are made of DNA
Cell

• DNA is a ladder-like double helix.
• Rungs of the ladder are made of pairs of four
  bases A, C, G, T

Nucleus
Sugar-phosphate backbone
Bases
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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

expression
protein
gene (DNA)
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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

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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

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Proteins govern traits

• An organisms appearance and qualities are the
  products of gene expression

expression
Genes
Proteins
Traits

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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
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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

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Breeding vs. Engineering
TRADITIONAL BREEDING
Donor
Commercial variety
New variety
(many genes transferred)

Desired gene
Desired gene
GENETIC ENGINEERING
Commercial variety
New variety
Desired gene
(one gene transferred)

(transfer)
Desired gene
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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

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Applications of Biotechnology

• Agricultural food production
• Improved production
• Disease resistance
• Herbicide tolerance
• Insect resistance
• Improved food quality
• Modified oils
• Delayed fruit ripening
• Nutritional enhancement

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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

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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
• Farmers point of view

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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 399214.

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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?

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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.

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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 18249-251.

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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/mai
n234240.shtml accessed 10 June 05
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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 2902088.
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Farmers 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)

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Applications of Biotechnology

• Agricultural food production
• Plants
• Animals
• Medical treatment
• Biopharmaceuticals
• Gene therapy
• Environmental detoxification
• Bioremediation
• Phytoremediation

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Animal production

• Improving production through cloning
• Strategy

Good producer
Clones (identical copies)
Interbreed
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Cloned Animals
Dolly and Mom
Calf Clones
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Medical treatmentsBiopharmaceuticals

• 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

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Using animals for pharmaceuticalsMolecular
pharming

• Proteins from milk of transgenic animals

Lactoferrin Clotting factor IX Insulin-like
growth factor
Iron supplement in infant formula Treatment of
hemophilia Treatment of diabetes
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Medical treatmentsGene therapy
David Vetter, the Bubble Boy
Severe Combined Immune Deficiency
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Applications of Biotechnology

• Agricultural food production
• Plants
• Animals
• Medical treatment
• Biopharmaceuticals
• Gene therapy
• Environmental detoxification
• Bioremediation by bacteria
• Phytoremediation by plants

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Environmental detoxificationPhytoremediation

• 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

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Phytodegradation
contaminant

• Enzymes in plant roots break down (degrade)
  organic contaminants.
• The fragments are incorporated into new plant
  materials.

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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.

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Genetics and Biotechnology