GENETIC ENGINEERING

What is genetic Engineering?

It is the process that involves the isolation, manipulation and reintroduction of DNA into model organisms, usually to express a protein in an organism. OR

Modifying DNA to remove, add, or alter genetic information is called genetic modification or genetic engineering.

• Genetic engineering works because there is one language of life. 

• Human genes work in bacteria, monkey genes work in mice and earthworms.  Tree genes work in bananas and frog genes work in rice. 

Brief History. The term "genetic engineering" was first

coined by Jack Williamson in his science fiction novel Dragon's Island, published in 1951.

In the early 1980s, scientists developed recombinant DNA techniques.

The first genetically engineered plant was tobacco that was resistant to herbicides, it occurred in France and the USA in 1986.

As of 2002, over forty food crops had been modified using recombinant DNA technology

including pesticide-resistant soybeans, virus-resistant squash, frost-resistant strawberries, corn and potatoes containing a natural pesticide, and rice containing beta-carotene.

• In 2010, scientists at the J. Craig Venter Institute, created the first synthetic bacterial genome. The resulting bacterium, named Synthia, was the world's first synthetic life form.

Discovery of Enzymes

• Key step in the development of genetic engineering was the discovery of restriction enzymes in 1968 by the Swiss microbiologist Werner Arber.

• However, type II restriction enzymes purified by American molecular biologist Hamilton O. Smith, which are essential to genetic engineering for their ability to cleave a specific site within the DNA.

• DNA ligases are enzymes used in the recombinant DNA technology to insert pieces of DNA cut by restriction enzymes into other DNA molecules submitted to the action of the same endonucleases.

Techniques for Genetic Engineering

• Recombinant DNA technology• Pieces of genes from an organism are inserted

into the genetic material of another organism producing recombinant beings; for example, the creation of of sheep Dolly.

Biolistics: • To inject DNA into cells by mixing the DNA with

small metal particles and then firing the particles into the host cell at very high speeds is biolistics

Apparatus for gene gun

Plasmid Technology: • The plasmids are tiny ringlets of DNA,

apart from the chromosome, that may contain 2-250 genes.

• Plasmid technology is the beginning of modem industrial microbiology. The plasmids can be spliced with genes from an unrelated organism.

Plasmid

Electroporation:• Electric shots are given to plant cells,

pores are created and foreign DNA is entered to cell.

Transformation by Agrobacterium tumefaciens

• It has tumor inducing plasmid i.e. Ti plasmid

• Gene of interest is inserted in plasmid• Then plants are infected by agrobacterium

Agrobacterium sp.

Ti Plasmid

• Gene of interest is then transferred to plants get the desired character e.g. genes or antibiotic resistance.

Microinjection:• DNA is injected to plants by micro

syringes.

The Biology Behind Genetic Engineering

Role of DNA:• DNA is the backbone for continuity of life.

The order of the four subunits A, G, C and T in the DNA strand holds a code of information for the cell.

• DNA is a ‘universal language’, meaning the genetic code means the same thing in all organisms.

• 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.

• By using genetic language it makes the proteins for the organism.

Structure of DNA

Role of Proteins:• They can be part of structures (such as

cell walls, organelles, etc). They can regulate reactions that take place in the cell. Or they can serve as enzymes, which speed-up reactions.

How Genetic Engineering is Done?

Process• find an organism that naturally contains

the desired trait. • The DNA is extracted from that organism.• The one desired gene must be located

and copied from thousands of genes that were extracted. This is called gene cloning

• The gene may be modified slightly to work in a more desirable way inside the recipient organism.

•  The new gene called a transgene is delivered into cells of the recipient organism. This is called transformation.

• Once a transgenic organism has been created, traditional breeding is used to improve the characteristics of the final product.

The first Commercial Genetic Engineered Food

First commercial genetically engineered foods was a tomato in which the gene responsible for softening was turned off.

Some Common Examples:

•Insulin genes in humans have been isolated and inserted into bacteria . The insulin that is then produced by these bacteria, is identical to human insulin.

Crystals of Insulin

• Chymosin, an enzyme that is involved in cheese manufacturing, have also been inserted into bacteria

• Genetic engineer has created a chicken with four legs and no wing.

• Genetic engineering has created a goat with spider genes that creates "silk" in its milk.

•Human cloning is a type of genetic engineering, but is not the true genetic manipulation.

• In human cloning, the aim is to duplicate the genes of an existing person so that an identical set is inside a human egg.

Cotton without Insecticides• Genetic engineers transferred the gene for

Bt toxin from Bacillus thuringiensis to cotton.• The bacterium produces a toxin which is

deadly to caterpillars Today, much of the US cotton crop is genetic engineered

• The only insects which it can harm are those which eat the plant.

Fast Growing Fish • Salmon take three years to grow from

fingerling size to optimum marketing size.

• In wild salmon turns on the gene for growth hormone only in the pituitary gland and primarily in warm water.

• So genetic engineers used a different control gene to turn on a growth hormone gene in cold water.

• That control gene was transferred from an ocean pout, and it turned on a gene for a protein that helped the pout tolerate very cold water.

• The new creature looks like wild salmon and its growth rate was faster than it.

Cure of Lung diseases in human:• Genetic engineering also includes

insertion of human genes into sheep so that they secrete alpha-1 antitrypsin in their milk - a useful substance in treating some cases of lung disease. 

Toxic Soils

• Some soils are poor for plant growth because their mineral content is toxic

• Recently, Florida scientists discovered a type of fern which can extract arsenic from the soil

• But other teams have identified genes that can enable plants to remove cadmium, zinc and mercury from soils., especially in acidic soils.

• Building with Silk • Silk is an extraordinarily strong material,

stronger than steel. It is composed of two proteins, fibroin and sericin.

• The gene for fibroin has been transferred from a silkworm to a goat, and is expressed as a component of its milk.

Applications of Genetic Engineering

• Agriculture:• One of the best-known applications of

genetic engineering is the creation of genetically modified food.

• These crops are resistant resistance to herbicides, fungal and virus infection tolerant against salt, cold or drought.

• Some of them are pharmaceutical crops that contain edible vaccines and other drugs.

Dandelion

Spider Onion

Banana fish

Underground potato frog

Blue Apple

Apple fish

Commercial Importance:• Yeasts are being engineered to yield enzymes for cheese

industry. Large scale amylase and cellulases are obtained.

Pollution Control:

• Nitrogen fertilisers are eliminated by incorporating plasmids containing bacterial genes for nitrogen fixation into the plant cells.

 

Bioremediation:• Bacteria have also been engineered to live

solely on toxic wastes in the environment. • A gene for hair digesting enzyme is

inserted into plasmid of bacteria.

Conclusion• Genetic engineering has given us the power to alter the very

basis of life on earth• Cross-breeding all work by using the same species. In contrast

genetic engineering allows to combine different genes in same oeganism.

• Genetic engineering therefore has few limits, our moral or ethical code.

• The recombinant DNA technology and cloning are extremely dangerous since they are able to modify, in a very short time.

 

• While making changes in organisms there is risk of creating diseases in them.

• It has application in every field of life.• Goal of technique is to add one or more

new traits that are not already found in that organism

Thank you…