Download Genetic Engineering Genetically

Genetic Engineering
Genetically-modified animals…
Bovine Growth
Hormone (BGH)
• Protein that increases
milk production when
injected
How did scientists get bacteria to
produce BGH?
Goals: Be able to…
• Describe the structure of DNA
• Translate DNA into protein
• Explain the process of gene expression
• Historical source:
Ground up cows
• New source: Bacteria
The structure of Deoxyribonucleic acid
What do you know about DNA?
Fig 2.13
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The structure of DNA
Nucleotide contains:
Nitrogenous
base
Phosphate
Each DNA
subunit:
nucleotide
Sugar
Fig 2.13
Fig 2.13
Nitrogenous
bases
Sugarphosphate
backbone
Fig 2.13
Fig 2.13
N-bases on one side base pair with partner on
the other
Fig 2.13
Fig 2.13
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Why is it important for DNA to have matching
base pairing?
GENE: DNA sequence that encodes a protein
DNA vs. RNA
How do DNA instructions result in proteins?
Gene expression!!
U instead of T
DNA
Transcription
RNA
Translation
Protein
Fig 8.3
DNA nucleotide
RNA nucleotide
Functional differences…
Fig 8.2
mRNA is transcribed from DNA
Nucleotides
Why is it important that RNA make proteins,
not DNA itself?
RNA polymerase
Transcription: Creating RNA from DNA template
mRNA = messenger RNA
Fig 8.4
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Gene expression
Keratin
DNA
Transcription
RNA
Translation
Protein
Fig 8.3
Fibroin
Lactase
The genetic code translates between RNA
language and protein language
tRNA is the translator molecule
Protein
3 mRNA nucleotides = codon = 1 amino acid
RNA
Fig 8.6
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mRNA and tRNA meet in the Ribosome
tRNA brings in amino acid that matches
mRNA codon
Ribosome
assembles protein:
Attaches amino
acids in a string
Fig 8.5
Fig 8.7
String of amino acids = protein
Enzyme, etc…
Real-time translation
Fig 8.7
Gene mutations Æ different amino acid Æ
different protein
Genetic mutation: Altered DNA nucleotide
Why could a genetic mutation lead to a
nonfunctional protein?
Fig 8.8
Cystic fibrosis movie
Fig 8.8
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What protein would this DNA sequence
make?
TACCCGGGGAAGAAATTCACT
TACCCGGGGAAGAAATTCACT
What protein would this DNA sequence
make?
AUG GGC CCC UUC UUU AAG UGA
TACCCGGGGAAGAAATTCACT
AUGGGCCCCUUCUUUAAGUGA
mRNA
met - gly - pro - phe - phe - lys - stop
Which of the following plays a role first during
gene expression?
A DNA strand that has the nucleotides A C G A G
would produce an RNA strand that read
A. RNA polymerase
A. T G C T C
B. Ribosome
B. A C G A G
C. tRNA
C. U G C U C
D. mRNA transcript
D. G T A G A
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Bovine Growth
Hormone (BGH)
Goals: Be able to…
• Define genetic engineering
How did scientists get bacteria to
produce BGH?
• Describe the basic steps involved in genetic
engineering
• List some applications of genetic engineering
• Explain how to engineer an animal
• Explain how the Ti plasmid works
• Support a position on genetic engineering
using scientific arguments
What would YOU do?
1. Isolate gene of interest
Genetic engineering: Using technology to
change genes in an organism
2. Put gene into vehicle
1. Isolate gene of interest
2. Put gene into “vehicle”
3. Vehicle puts new gene into organism
3. Vehicle puts new gene
into organism
Fig 8.12
1. Isolate gene of interest: Remove gene from
cow chromosome
Use biological scissors:
restriction enzymes
Fig 8.12
Restriction enzymes cut DNA only at specific
sequences
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2. Put gene into vehicle: Bacterial plasmid
Use SAME
restriction
enzymes to cut
plasmid
Plasmid is recombinant: contains DNA from >1
source
Sticky ends base pair
rBGH
Fig 8.12
Bacteria are promiscuous
TRANSFORMATION
3. Vehicle puts gene into
new organism: Bacteria
uptakes plasmid
Free DNA
Bacteria are now transgenic
Bacterial DNA
Plasmid
Fig 8.12
Bacteria produce large amounts
of cheap rBGH
Design your own multiple choice question about
the process of genetic engineering. Test it on
your friend.
Farmers inject the protein into cows
Fig 8.12
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Human insulin produced in E. coli bacteria
Is this genetically engineering humans? If
not, what was engineered?
How do you feel about genetically engineering
bacteria?
Socioeconomic Implications
rBGH…
Are farmers benefiting from using rBGH?
Monsanto vs. Oakhurst
Humans were not
the first genetic
engineers…
Viruses inject their
own genes
Fig 10.1
Gene Therapy
What is being genetically engineered here?
Viral genes make
new viruses
Viruses inject non-mutant (normal) gene
Fig 8.21
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What are some reasons people want to
genetically engineer foods?
• More production (bigger)
Genetically-engineered foods and crops
http://www.colostate.edu/programs/lifesciences/TransgenicCrops/current.html
What are some reasons people want to
genetically engineer foods?
What are some reasons people want to
genetically engineer foods?
• More production (bigger)
• More production (bigger)
• Healthier foods
• Healthier foods
• Herbicide-resistant plants
Golden rice
What are some reasons people want to
genetically engineer foods?
• Insect-resistant plants
PHARM ANIMALS
• More production (bigger)
• Healthier foods
• Herbicide-resistant plants
• Insect-resistant plants
• “Pharm”aceutical organisms
Cystic fibrosis proteins
Multiple sclerosis proteins
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Creating completely transgenic animals…
Insert genes into animal embryos, then transplant
into surrogate mother.
egg
Inject genes
Should we allow genetic engineering of humans in
order to prevent incurable diseases?
GM
sheep
Genetic engineering of humans?
Plant genetic engineering
Use a “gene gun”
Engineering plants
Fig 8.16
Ti (tumor-inducing) plasmid
Genetic engineering by bacteria
Ti plasmid of Agrobacterium tumefaciens
food synthesis
T-DNA:
transferred to
plant
Plant
hormones
Fig 8.15
opbs.okstate.edu/ ~petracek/CHAPTER%2029
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T-DNA on plasmid
Ti plasmid
Agrobacterium
tumefaciens
Agrobacterium
Bacteria cuts T-DNA
from its plasmid
T-DNA inserted
into plant
chromosome
Movie
New
gene
Ti plasmid with
new gene instead
of T-DNA
Recombine engineered Ti
plasmid with Agrobacterium
Why are plants able to read genetic instructions
from bacteria?
Agrobacterium infects plant and
inserts new gene into plant
chromosome
Humans have been modifying organisms
for thousands of years…
What’s different now?
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GM foods and human health
Genetic engineering: What’s different from
breeding?
• Shorter time period than traditional
breeding.
• Exchange of genes between
organisms that cannot mate in nature.
What happens to the DNA that we eat?
GM foods and human health
GM crops and the environment
DNA is not an allergen
• Risks to nontarget organisms
Some proteins are allergens
GM crops and the environment
GM crops and the environment
• Risks to nontarget organisms
Bacillus thuringiensis
(Bt) makes toxic protein
Bt gene engineered
into corn so it
produces toxic protein
Fig 8.19
Problem: toxin kills ALL caterpillars
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GM crops and the environment
Round-up Ready
plants are herbicideresistant
• Risks to nontarget organisms
• Evolution of resistant pests and weeds
Encourages farmers to spray more herbicide
Herbicide resistance can also spread in weeds
GM crops and the environment
• Risks to nontarget organisms
• Evolution of resistant pests and weeds
• Threats to native diversity
Roundup-Ready canola
Biological systems are more unpredictable
than physical systems
Escape and competition
Human safety and human error.
StarLink corn
(Marvier and VanAcker 2005)
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Do you think that genetically-engineered
products should be labeled? Why or why not?
How do genetic engineers get genes into
bacteria?
A. They shoot them with a gene gun.
B. They inject the DNA into an egg nucleus.
C. They cut open the bacteria using restriction
enzymes.
D. They incorporate genes into plasmids, which
bacteria take up from their surroundings.
Which of the following is a true statement?
A. A farmer injects rBGH into cows. She is
genetically engineering the cows.
B. A doctor injects recombinant human insulin
into a child. He is engineering the child.
C. A doctor injects engineered viruses into a
patient in order to modify her DNA. He is
engineering the patient.
E. Bacteria cannot be genetically engineered.
Why does Agrobacterium tumefaciens engineer
plants?
A. To make the plant produce toxic Bt proteins.
B. To make the plant produce food and a home for
it.
C. To make the plant produce rBGH.
D. Agrobacterium does not engineer plants.
Humans use its Ti plasmid.
Which of the following is NOT a valid argument
against genetic engineering?
A. It is unnatural.
B. Genes may escape into wild relatives.
C. Proteins produced may have affects on nontarget organisms.
D. Insect pests and weeds may become resistant
due to overuse of engineered products.
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