Biotechnology
Chapter 17 section 1 (only)
5-16-16
Learning Goals for Today:
• Explain how DNA profiling can identify individuals
• Interpret data from DNA electrophoresis
• Discuss genetically modified organisms
• Explain some ways DNA can be recombined in nature
What Is Biotechnology?
• Biotechnology is the use of organisms, cells, or biological molecules to produce food, drugs, or other goods – Yeast: fermentation (10,000 years ago)– Selective breeding of animals/plants (between 6
and 15,000 years ago)– cloning– genetic engineering– Finger-printing– Genome sequencing– Diagnosing and treating diseases
• Merriam Webster’s definition of natural: “being in accordance with or determined by nature”
Is all this natural?
According to nature
Lemon
Corn
Banana
PigDog
Things that we assume com straight from nature, do not!
ALL dogs come from the wolf!
All these veggies come from wild mustard!
Genetically Modified Organism (GMO):
– an organism that contains foreign DNA
– w/ altered characteristic(s)
– does not occur naturally because the selection pressure in for human benefit
– obtained via cloning technology
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Genetic engineering
• Recombinant DNA - combining DNA molecules not found together in nature; via cloning
How Does DNA Recombine in Nature?
• Bacteria and yeast: can take in DNA from the environment– Transformation
• DNA piece can come from a the same or a different species
plasmid
plasmid
bacterial
chromosome
(a) Bacterium
DNA
fragments
bacterial
chromosome
(b) Transformation with a DNA fragment
(c) Transformation with a plasmid
A DNA fragment is
incorporated into
the chromosome
bacterial
chromosome
The plasmid replicates
in the cytoplasm
1 micrometer
Transformation in Bacteria
Fig. 13-1
Bacteria can take in DNA from their environment
New DNA might code for anything
Big Issue: Genes for antibiotic resistance
Viruses Also Transfer DNA
Fig. 13-2
The virus releases itsDNA into the host cell; some viral DNA (red) may be incorporated intothe host cell’s DNA (blue)
The virus enters the host cell
Viral genes encode the synthesis of viral proteins and viral gene replication; some host cell DNA may attach to the replicated viral DNA (red/blue combination)New viruses assemble;
some host cell DNA is carried by recombinant viruses
The host cell bursts open, releasing newly assembled viruses; if recombinant viruses infect a second cell, they may transfer genes from the first cell to the second cell
viral proteinsrecombinant virus
virus
viral DNA
viral DNA
A virus attaches to a susceptible host cell
host
cell
host cell DNA
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3
1
4
5
6
Types of Cloning
• Molecular cloning (DNA cloning)
– Manipulating a small piece of DNA, typically using bacteria as host
• Therapeutic cloning
– Creating stem cell lines with same DNA as a patient, used for treating diseases and disorders
• Reproductive cloning
– Technique used to generate an animal with exact genetic makeup (DNA) as another animal
Genetic Engineering
Recombinant DNA - combining DNA molecules not found together in nature; via cloning
DNA Cloning –
– Molecular cloning
– Inserting foreign DNA from one organism into another
what is it?
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Bacteria can transfer DNA into plants
• Agrobacterium infects plants
• Physically injects part of its own DNA into the plant cell
• Plant will grow a gall at the infection site– Bacteria live in the gall
– Plant synthesizes nutrients for the bacteria
• Similar process with Rhizogenes bacteria but the end result benefits the plant
Agrobacterium is a natural, and
commonly used, plant genetic engineer
The “gene gun” is also used to introduce
DNA into cells
After cells are
modified, they
are induced to
regenerate into
whole plants
Where are GM foods?
The Marketplace
– 60 to 70% of processed food contains GMO
In the US:
– Corn ~45% is GM
– Soybean ~85% is GM
– Cotton ~76% is GM
– Canola ~60% is GM
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Biotech crops widespread, rapidly
adopted: Grown on >10% arable land on planet,
extensive uptake in developing world
http://www.isaaa.org/resources/publications/briefs/46/pptslides/Brief46slides.pdf
Four crops dominate,
8+ crops in USA
http://www.isaaa.org/resources/publications/briefs/46/pptslides/Brief46slides.pdf
Two traits dominate worldwide
http://www.isaaa.org/resources/publications/briefs/46/pptslides/Brief46slides.pdf
Newly approved GE crop varieties in
USA • Soybean – insect resistant (Apr. 2014)
• Alfalfa – reduced lignin (Nov. 2014)
• Potato – reduced black spot bruise and low acrylamide production (Nov. 2014), reduced browning and disease resistant as well (August 2015)
• Soybean and cotton – new herbicide tolerances (Jul. 2014 – Jan. 2015)
• Apple – non-browning (Feb. 2015)
• Plum – virus resistant (2014)
Non-browning “Arctic Apple” Reduced spoilage/waste, improved quality – USDA
approved
Courtesy of Jennifer Armen, Okanagan Specialty Fruits, Canada
Non-browning “Arctic Apple” Time lapse video
“Innate” potato approved – reduced browning
and acrylamide (↓waste, ↑safety)
“Innate” potato in my hands for teaching
One hour after cutting – Control vs. Innate
Two days after cutting – Innate vs. Control
“Innate” potato 2.0 – late blight resistant,
reduced acrylamide, reduced sprouting and
browning (↓ waste, ↑ safety, ↓ pesticide, ↑ yield)
Dramatic change in color of chips,
highly prized by consumers
Provided by Walter De Jong, Cornell University
Scientific AmericanMarch, 2013
Resistance transgenes promising solution/s to devastating ‘citrus greening’
Face the “wall of opposition” ?
Defensin-like proteins from spinach
for citrus greening disease resistance
Courtesy of Eric Mirkov, Texas A & M
Helping forests: American Chestnut
restoration by genetic modification
March 2014 issue - Scientific American
Forest health a major and growing
concern
Diverse pipeline of biofortification
products = enhancement of critical
vitamins or nutrients
Many more examples funded by Gates Foundation / other sources
• Rice
• Cassava
• Sorghum
• Banana
Biotech methods useful where breeding is
ineffective or slow
RiceCassava
Management of monocultures
• Mismanagement promotes the proliferation of weeds resistant to herbicides and bugs resistant to pesticide– Many weeds have developed resistance to glyphosate
(RoundUp)
– Rootworms have also developed resistance to Bt
• Herbicide can kills plants that are not weeds– Milkweed supplies Monarch butterflies eat
• Rotating crops, eliminate volunteers, and creating havens with no pesticide
Cloned Stem Cells• Immune system will recognize & destroy cells with different DNA
• Therefore, stem cells need to contain same DNA as patient
• Cloned Stem Cells -
• Somatic Cell Nuclear Transfer
“Therapeutic Cloning”
Somatic cells = all body cells
Nucleus = region of cell containing DNA
Transfer = remove and replace
Somatic Cell Nuclear Transfer
https://www.youtube.com/watch?v=tELZEPcgKkE
Induced Pluripotent Stem cells
(iPScells)
• Reprogramming somatic cells (skin) so they
behave as stem cells
• Can replace embryo harvesting
• Human cloning not needed
• Used for therapeutic cloning
• Must add new proteins (transcription factors)
to reprogram
https://www.youtube.com/watch?v=Q9-
4SMGiKnE
https://www.youtube.com/watch?v=Q6U5kf5By
NE
How Is Biotechnology Used in Forensic Science?
• DNA identification: huge role in criminal investigations
• Individual have unique DNA sequences
– DNA “fingerprint”
• How to we figure out a person’s DNA “fingerprint”?
Differences in short tandem repeats (STRs) can identify individuals by their DNA
• STRs: noncoding DNA
– STRs are not transcribed into mRNA
– Short sequence of 2-5 nucleotides
– Repeated many times (up to 50)
– All in a row (in tandem)
• Number of repeats varies (different alleles)
Example of a STR
Fig. 13-4
Eight side-by-side (tandem) repeats
of the same four-nucleotide sequence
Using STRs to Identify Individuals
• Different people may have different alleles of the STRs – Allele: number of repeats
• U.S. Department of Justice – 13 standard STRs tested
• Over a trillion possible combinations of alleles
– Exact match needed for conviction
https://www.youtube.com/watch?v=9bEAJYnVVBA
Question for Thought:
• DNA fingerprinting is very useful– Paternity/mate
rnity testing– Criminal
investigations
• Should there be a national database of everyone’s DNA?
How do we figure out someone’s DNA “fingerprint?”
• DNA sequence cannot be read directly
• Sequencing entire genomes is expensive and takes time
• Sometimes there isn’t much DNA in the sample
• PCR: a technique for making lots of DNA copies of specified pieces of DNA
PCR: the Polymerase Chain Reaction• Modern version developed by Kary Mullis
• Only need a tiny amount of starting DNA
• Makes lots of copies of DNA of interest
DNA Learning Center, Cold Spring Harbor Laboratory
Gel electrophoresis: a method to examine PCR results
• After PCR: a lot of pieces of DNA
– Often alleles are different sizes
• Gel electrophoresis: a method to separate DNA based on size
Example of DNA Profiling for one STR
DNA samples from
13 different people
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13
12
11
10
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D16: An STR on chromosome 16
Nu
mb
er
of
rep
eat
s
Why do some people have 1 band and some people have 2 bands?
DNA Profiling
Fig. 13-7
STR name
Penta D
CSF
D16
D7
Mutations
• Substitutions or point mutations
• Insertions
• Deletions
• Inversions
• Translocations
Due to errors during replication (1 in 100,000, but proof-reading fixes 99%) or external factors like toxins and radiation
Mutations in STRs
• STRs: Sequence Tandem Repeats (forensics)
• Errors are due to replication slippage
• Slippage occurs in STRs about 1 per 1000 generations
Replication slippage
Other uses for gene sequencing
• Genes other than the STRs are often sequenced
– Health-related tests
– Studying gene function
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