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

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

Cloned Animals

Dolly and Mom

Calf Clones

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

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

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.

Genetics and Biotechnology