biotechnology - linn–benton community...
TRANSCRIPT
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Biotechnology
Chapter 17 section 1 (only)
5-16-16
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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
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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
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• Merriam Webster’s definition of natural: “being in accordance with or determined by nature”
Is all this natural?
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According to nature
Lemon
Corn
Banana
PigDog
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Things that we assume com straight from nature, do not!
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ALL dogs come from the wolf!
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All these veggies come from wild mustard!
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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
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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
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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
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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
2
3
1
4
5
6
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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
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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
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Agrobacterium is a natural, and
commonly used, plant genetic engineer
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The “gene gun” is also used to introduce
DNA into cells
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After cells are
modified, they
are induced to
regenerate into
whole plants
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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
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Four crops dominate,
8+ crops in USA
http://www.isaaa.org/resources/publications/briefs/46/pptslides/Brief46slides.pdf
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Two traits dominate worldwide
http://www.isaaa.org/resources/publications/briefs/46/pptslides/Brief46slides.pdf
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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)
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Non-browning “Arctic Apple” Reduced spoilage/waste, improved quality – USDA
approved
Courtesy of Jennifer Armen, Okanagan Specialty Fruits, Canada
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Non-browning “Arctic Apple” Time lapse video
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“Innate” potato approved – reduced browning
and acrylamide (↓waste, ↑safety)
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“Innate” potato in my hands for teaching
One hour after cutting – Control vs. Innate
Two days after cutting – Innate vs. Control
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“Innate” potato 2.0 – late blight resistant,
reduced acrylamide, reduced sprouting and
browning (↓ waste, ↑ safety, ↓ pesticide, ↑ yield)
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Dramatic change in color of chips,
highly prized by consumers
Provided by Walter De Jong, Cornell University
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Scientific AmericanMarch, 2013
Resistance transgenes promising solution/s to devastating ‘citrus greening’
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Face the “wall of opposition” ?
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Defensin-like proteins from spinach
for citrus greening disease resistance
Courtesy of Eric Mirkov, Texas A & M
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Helping forests: American Chestnut
restoration by genetic modification
March 2014 issue - Scientific American
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Forest health a major and growing
concern
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Diverse pipeline of biofortification
products = enhancement of critical
vitamins or nutrients
Many more examples funded by Gates Foundation / other sources
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• Rice
• Cassava
• Sorghum
• Banana
Biotech methods useful where breeding is
ineffective or slow
RiceCassava
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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
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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
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Somatic Cell Nuclear Transfer
https://www.youtube.com/watch?v=tELZEPcgKkE
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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
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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”?
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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)
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Example of a STR
Fig. 13-4
Eight side-by-side (tandem) repeats
of the same four-nucleotide sequence
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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
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Question for Thought:
• DNA fingerprinting is very useful– Paternity/mate
rnity testing– Criminal
investigations
• Should there be a national database of everyone’s DNA?
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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
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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
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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
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Example of DNA Profiling for one STR
DNA samples from
13 different people
15
14
13
12
11
10
9
8
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?
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DNA Profiling
Fig. 13-7
STR name
Penta D
CSF
D16
D7
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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
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Mutations in STRs
• STRs: Sequence Tandem Repeats (forensics)
• Errors are due to replication slippage
• Slippage occurs in STRs about 1 per 1000 generations
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Replication slippage
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Other uses for gene sequencing
• Genes other than the STRs are often sequenced
– Health-related tests
– Studying gene function