Application of genetic engineeringBy,Pillai Aswathy viswanathPG 1 BotanySt. Thomas college kozhencherry
Genetic engineering, also calledgenetic modification to add one or more new traits that are not already found in that organism.In France , this technology is called biomolecular engineering In 1973,Stanley Cohen and Herbert Boyer designed a methodology for transferring certain genes from one organism to another
The gene is a small piece of DNA that encoded for a specific proteinA desired gene is inserted in to a vector DNA so that a new combination of vector DNA is formedThe DNA formed by joining DNA segments of two different organisms is called recombinant DNA or chimeric DNAThe gene is introduced in to a cell in the form of recombinant DNAThe gene manipulation therefore is known as recombinant DNA technology
The organism whose genetic make up is manipulated using recombinant DNA technique , is called genetically modified organism(GMO).
GMOs produced through genetic technologies have become a part of everydaylife,
However, while GMOs have benefited human society in many waysGenetic engineering techniques have been applied in numerous fields including :-
Agriculture Medicine Genetic studies . etcsome disadvantages also exist; therefore, the production of GMOs remains a highly controversial topic in many parts of the world.
Application in AgricultureImprovement in agricultural production and the food and nutrition situation depents on land ,water and energy resources.From 1970 a new type of reasearch started with the aim of producing new varieties of plants by genetic recombination techniques.They are genitically engineered plants They have acquired a new trait from the introduced DNA and inherit the trait for many generations
The new plants produced by such techniques are supposed to be:-
virus resistant plant insect resistant plants, herbicide resistant plant growing crops of your choice (GM food)for preservation of fruitsSome genetically engineered microorganisms are used as nitrogen fixers
virus resistant plantto make virus resistant crops.The most common way of doing this is by giving a planta viral gene encoding the virus' 'coat protein'.The plantcan then producethisviral protein before thevirus infects the plant.When the virus tries to infect the plant, the production of its essentialcoat protein is already blocked.
Tansgenic tobacco is developed by introducing gene coding for capsid protien of tobacco mosaic virusTMV-coat protein inserted in to tobacco cell using Ti plasmid Viral capsid inhibit viral replication of TMV when infectedAllgenetically modifiedvirus resistant plants on the market (e.g. papayas and squash) have coat protein mediated resistance.
GM squash with virus resistance (top) protects the squash from the damaging effects of the virus (bottom)papaya with virus resistance
insect resistant plants,Insect attack is a serious agricultural problem leading to yield losses and reduced product quality. Each year, insects destroy about 25 percent of food crops worldwide. many transgenic plant with insect resistantance have been developed by adopting gene transfer methodsThe gene helps the plants produce proteins that are toxic to certain insectsThey reduced the use of chemical pesticides in agriculture
The genetically modified crops is called Bt-crops, because the insect-killing gene in the plant comes from the bacteriaBacillus thuringiensis.Bt gene produces insecticidal crystal protien (ICP) also known as cry protien which is in an inactive, crystalline form.When consumed by insects, the protein is converted to its active, toxic form (delta endotoxin), which in turn destroys the gut of the insect and is completely safe for humans.
Examples of some Bt crops A common soil bacterium so called because it was first isolated in the Thuringia region of Germanydiscoverd by Ishiwatari in 1901
herbicide resistant plant Many transgenic plants with herbicide resistance have been developed by using genetic engineering Such transgenic plants tolerate the herbicides and be safe in the field ,when the herbicides are applied in the field
Example for herbicide resistant plant
Growing crops of your choice Genetically modified foods are foods derived from genetically modified organisms.
The FLAVR SAVR tomato was the first genetically engineered crop productThrough genetic engineering, the ripening process of the tomato will slow down and thus prevent it from softening, while still allowing the tomato to retain its natural colour and flavour.Thus the shelf life of the tomato become improved
The tomato was made more resistant torottingby adding angene which interferes with the production of theenzymepolygalacturonase. The enzyme normally degradespectinin thecell walls and results in the softening of fruit which makes them more susceptible to being damaged byfungal infections.Improved taste and look
BiofertilizersGenetically engineered nitrogen fixersNitrogen is the most essential macro-element for proper healthy cropMolecular nitrogen in the atm. Is converted to biologically usable forms by nitrogen fixing micro organisms eg:RhizobiumIn leguminous plants nitrogen fixing nodules are formed in the roots due to the symbiotic realation ship with bacteriaThe special ability of nitrogen fixing bacteria is due to the presence of an enzyme called nitrogenase complex
Some genetically engineered micro organism are used as nitrogen fixers rizobium species carry nif genes , later genes will transferred to the free living bacteris like klebsiella pneumoniae ,salmonella typhimurium etcThese genetically engineered microbes are capable of fixing the atmospheric nitrogen in the soil they are used as biofertilizers in agriculture.
In 1971 dixon and postgate successfully transferred the nif genes to free living nitrogen fixer klebsiella pneumoniaeKlebsiellais naturally found as a free-living soil bacterium
Application in Medicine.Some of the most promising and powerful applications of genetic engineering are in the field of medicine. Researchers are using it to diagnose and predict disease, and to develop therapies and drugs to treat devastating diseases like cancer, Alzheimer's, diabetes, and cystic fibrosis. Etc.At present about 30 recombinant therapeuties have been approved for human use
The application of recombinant DNA technology has played a major role in:-
Production of human insulin Production of human growth hormone Production of vaccines production of interferons Gene therapy
Production of human insulin
Insulin is a hormons produced by beta cellsin thepancreas that controls the absorption of glucose by cells.The deficiency of insulin leads to diabetics in manDiabetics is treated by injecting insulin In the past, diabetics needed to take insulin purified from pigs and cows to fulfill their insulin requirement. However, non-human insulin causes allergic reactions in many diabetics.
Recombinant DNA technology has allowed the scientists to develop human insulin by using the bacteria as a host cellit is also available in the market. It is believed that the drugs produced through microbes are safer.
Production of human growth hormone
Human growth hormone (HGC) is secreted by the anterior lobe of pituitary gland . It also called somatotropin The deficiency of somatotropin leads to dwarfism in manThe cDNA of somatotropin was introduced in to Ecoli The genetically engineered E coli produces human growth hormone
Production of vaccines
Avaccineis a biological preparation that improves immunity to a particulardiseaseGenetic engineering is used to developed vaccines against some sever diseasesHepatitis B vaccines, First human trials of vaccine against Hepatitis BA gene coding for surface antigen HBsAg was isolated from Hepatitis B virus and cloned in EcoliThe genetically engineered microbes will produced HBs antigenThis antigen is isolated purified and used for vaccination
Edible Vaccine involves introduction of selected desired genes into plant and then inducing these altered plants to manufacture the altered protein.Banana is currently being considered as the edible vaccine against hepatitis B
Production of interferonsInterferons is an antiviral protein.Interferons is produced by infected animal cells and it protects the cells from the second viral infectionThey induced the production of cellular protein kinase and phosphodiesterase which selectively destroy viral RNAs and proteins. So the virus fail to multiply in the cell
The cDNA of the various interferons were isolated from human cell and introduced in to E coli The genetically engineered E coli cultures produced interfrons
Medical scientists now know of about 3,000 disorders that arise because of errors in an individual's DNA.Conditions such as sickle-cell anemia, Huntington's chorea, cystic fibrosis, and Lesch-Nyhan syndrome are the result of the loss, mistaken insertion, or change of a single nitrogen base in a DNA molecule.Genetic engineering makes it possible for scientists to provide individuals who lack a certain gene with correct copies of that gene.
Treatment of genetic disorders by replacing defective gene by a normal functional gene is called gene