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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.