1. BTY100-Lec#5.1
Genetic Engineering
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2. Outline Introduction to Genetic Engineering Goal Tools Process
Molecular Scissors
Cloning Vectors
Process
Enhanced Traits- Bt Crops
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3. Genetic Engineering Goal
Altering/ Manipulating the traits of living organisms by changing the information encoded in their DNA.
Goal
To add one or more new traits that are not naturally already found in that organism. 
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4. Altering DNA? Is it possible?
DNA is a ‘universal language’. The genetic code means the same thing in all organisms.
All living organisms have the same bases (A, T, G, C) which code for proteins.
The codons they form always code for the same amino acids, so transferred DNA codes for the same polypeptide chain in the host organism as it did in the donor organism.
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5. Human appearance is a results of the information stored in our genes
Human appearance is a results of the information stored in our genes. Differences in Eye color, hair color, skin complexion, height etc all are due to different information stored in different persons.
Does it means any change in our DNA will result in some change in our appearance?
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6. Changing faces of Michael Jackson….?????
A Question for you….?
In one of the most memorable moments of Oprah's interview, Michael told her he had a skin disorder that destroyed the pigmentation of his skin. The disease, called vitiligo, was in his family, Michael said. "It is something I cannot help”.
Genetic Engineering? OR
Skin Bleaching? OR
Skin Disease???
He kept getting whiter and whiter and whiter, and nobody understood why
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7. Coming back to our Question
Does it means any change in our DNA will result in some change in our appearance?
Answer- NO, The Purpose of science is not this……. Ultimate aim of all type of researches is to benefit the society.
In this unit we will be discussing the examples which were created for some useful purpose.
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8. How does Genetic Engineering work?
removing a gene from one organism and inserting it into another (a process called gene transfer).
When a gene for a desirable trait is taken from one organism and inserted into another, it gives the ‘recipient’ organism the ability to express that same trait.
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9. Glossary
Donor cell- is the cell that provides the new DNA fragment for the recipient cell
Recipient cell/Host Cell- is the cell that is reviewing the ‘new’ DNA.
Target Gene/Foreign DNA- Gene with the desired trait.
Ligation- Uniting attaching two DNA fragments.
DNA recombination- The DNA fragment to be cloned is inserted into a vector.
Transformation- The recombinant DNA enters into the host cell and proliferates
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10. GENETIC ENGINEERING: PROCESS
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11. PROCESS:
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12. Tools for Genetic Engineering
Molecular Scissors
Construct/Cloning Vectors
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13. Molecular Scissors
Restriction enzymes are DNA-cutting enzymes found in bacteria.
A restriction endonuclease : cuts DNA at or near a particular place known as restriction sites.
E.g. EcoRI:
always cuts at site: GAATTC
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14. Cloning Vectors A DNA molecule that:
carries foreign DNA into a host cell.
replicates inside cell and produces many copies of itself and the foreign DNA.
E.g.: Plasmid: an extrachromosomal circular DNA molecule that replicates on its own inside the bacterial cell
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15. Transformation
The plasmids carrying the desired traits are introduced into host cells via a process called transformation.
Bacteria are most commonly used as host cells for gene cloning because :
Their DNA can be easily isolated and reintroduced into their cells.
Bacterial cultures also grow quickly, rapidly replicating the foreign genes.
Bacteria will also produce large amounts of the protein of interest
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16. Process… Gene of interest is cut out with Restriction enzyme.
Host plasmid is cut with same Restriction enzyme.
Gene is inserted into plasmid and ligated with ligase enzyme
New plasmid inserted into bacterium (transform).
Bacteria divides and plasmid divides along with that.
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17. Genetic Engineering: Enhanced Traits
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18. Bt Crops
Are crops that are genetically engineered to produce the same toxin as produced by B. thuringiensis in every cell of the plant, with the goal of protecting the crop from pests.
Examples: Bt Cotton, Bt corn, Bt Brinjal
What is Bt?
Bacillus thuringiensis (Bt) is a spore forming bacterium that produces crystals protein (cry proteins), which are toxic to many species of insects
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19. Bt Cotton
Bt Cotton is a variety of cotton that has been genetically engineered to produce an insecticide in every cell.
It contains the gene coding for Bt toxin, causing cotton plant to produce this natural insecticide in its tissues.
In many regions, the main pests in commercial cotton are lepidopteran larvae, which are killed by the Bt protein in the transgenic cotton they eat.
This eliminates the need to use large amounts of broad-spectrum insecticides to kill lepidopteran pests
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20. How Bt Works?
When insects attack and eat the cotton plant the Cry toxins are dissolved.
This is made possible due to the high pH level of the insects stomach.
The now dissolved and activated Cry molecules bind to cells in the insect gut and results in the death of epithelial cells.
The death of such cells creates pores in the insect gut and insect dies eventually.
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21. Why Bt is not toxic to Humans?
The specificity of Bt rests on the fact:
For the activation of toxin, alkaline conditions are required as provided by insect gut but the human stomach has a pH of  1.5 to 3.5.
The toxicity of the Bt protein is receptor-mediated. This means that for an insect to be affected by the Bt protein, it must have specific receptor sites in its gut where the proteins can bind. Humans do not have these receptors.
Before Bt crops are placed on the market, they must pass very stringent regulatory tests, including those for toxicity and allergenicity.
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22. Advantages Reduced environmental impacts from pesticides
Increased opportunity for beneficial insects
Reduced pesticide exposure to farm workers and non-target organisms
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23. Risks
Invasiveness – Genetic modifications can potentially change the organism to become invasive.
Resistance to Bt - The biggest potential risk to using Bt-crops is resistance. Farmers have taken many steps to help prevent resistance.
Cross-contamination of genes - Although unproven, genes from GM crops can potentially introduce the new genes to native species.
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24. Next Class: Genetic Engineering:A Potential Solution
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