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