BIOTECHNOLOGY AND ITS APPLICATIONS (notes)

 

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REVISION NOTES

BIOTECHNOLOGY AND ITS APPLICATIONS

Biotechnology mainly deals with industrial-scale production of biopharmaceuticals and biologicals using genetically modified microbes, fungi, plants and animals, its applications include: 

• Therapeutics 

• Diagnostics 

• Genetically modified crops for agriculture

• Processed food 

• Bioremediation 

• Waste water treatment and 

• Energy production 

Three critical research areas of biotechnology are: 

(i) Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme. 

(ii) Creating optimal conditions through engineering for a catalyst to act, and 

(iii) Downstream processing technologies to purify the protein/organic compound.

Application of Biotechnology in Agriculture Food production can be increased by: 

(i) Agro-chemical based agriculture 

(ii) Organic agriculture 

(iii) Genetically engineered crop based agriculture 

Genetically Modified Organisms: organisms like bacteria, fungi, plants and animals whose genes have been altered by manipulation is called genetically  modified organisms (GMO). 

Genetic modification made plants and crops: 

• More resistant to abiotic factors

• Reduced the use of chemical-based fertilisers 

• Increased nutritional value of food. E.g. golden rice, i.e., Vitamin ‘A’ enriched rice

 • helped to reduce post harvest losses. 

• increased efficiency of mineral usage by plants 

• Additionaly, GM has been used to create tailor-made plants to supply alternative resources to industries, in the form of starches, fuels and pharmaceuticals.

Application of Biotechnology in the production of Pest-resistant plants 

Pest-resistant plants reduce the need for insecticides. Bacillus thuringiensis is a bacterium that produces Bt toxin. The Bt toxin gene was cloned from bacteria and produced in plants to give insect resistance without the use of pesticides, thereby creating a bio-pesticide.

 Bt cotton, Bt corn, rice, tomato, potato, and soyabean are a few examples.

Bt Cotton-An overview: Bacillus thuringiensis produces proteins that kill insects such as lepidopterans, coleopterans (beetles), and dipterans (flies, mosquitoes). 

B. thuringiensis generates crystals containing a poisonous insecticidal protein. This toxic protein exists in bacteria as inactive protoxins, but when an insect consumes the inactive form due to the alkaline pH of the gut, it converts into an active form of toxin and binds to the surface of midgut epithelial cells, creating pores that cause cell swelling and lysis, and eventually death of the insect. 

The Bt. thuringiensis gene has been introduced into a variety of agricultural species, including cotton, maize, and rice. The toxin is encoded by the cry gene. Cotton bollworms are controlled by the protein coded by the genes crylAb and cryIIAb, while corn borer is controlled by cryIAb. 

Pest Resistant Plants

 Meloidegyne incognitia, a nematode, infects the roots of tobacco plants and reduces output. The method of RNA interference can be used to prevent the invasion of these worms (RNAi). RNAi is found in all eukaryotic creatures and serves as a cellular defence mechanism by silencing certain mRNA molecules via complementary dsRNA molecules that bind to and impede mRNA translation. 

The source of complementary dsRNA may be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate through RNA intermediate.

 Nematode-specific genes were introduced into host plant using Agrobacterium vectors. The parasite could not survive in a transgenic host expressing specific interfering RNA.

Application of Biotechnology in Medicine 

The rDNA technology procedures have had a huge influence on healthcare by allowing for the mass manufacturing of safer and more effective medicinal medications. Currently, over 30 recombinant medicines have been authorised for human use worldwide. In India, 12 of these are currently on the market.

Genetically Engineered Insulin: An overview 

Adult-onset diabetes can be managed by using insulin at regular intervals. The extraction of insulin from animals was the primary source of this insulin. Insulin may now be produced from bacteria utilising biotechnology processes.

 

Previously, insulin was extracted from the pancreas of slaughtered cattle and pigs, but insulin derived from these sources causes allergy or other sorts of responses to the foreign protein.

Insulin is made up of two short polypeptide chains, A and B, that are joined together by disulphide bridges.

In humans, insulin is synthesised as a prohormone that has an additional stretch known as C-peptide that is missing in mature insulin.

The biggest problem in producing insulin with the rDNA approach was assembling insulin into a mature state.

 In 1983, an American corporation, Eli Lilly, synthesised two DNA sequences matching to the A and B chains of human insulin and put them into E.coli plasmids to create insulin chain. Chain A and Chain B were created independently, extracted and then combined to make human insulin by forming disulphide linkages.

Gene Therapy:  It is a collection of methods for correcting a gene abnormality that has been identified in a kid or embryo. In the case of a hereditary illness, this procedure is used. Here genes are inserted into a person’s cells and tissues to treat a disease. Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.

 The first clinical gene therapy was performed on a four-year-old child with adenosine deaminase (ADA) deficiency in 1990. This condition is caused by the loss of the adenosine deaminase gene, which is required for the immune system to operate. The disorder is caused due to the deletion of the gene for adenosine deaminase. In some children ADA deficiency can be cured by bone marrow transplantation; in others it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection. This method is not completely curative hence, lymphocytes from the patient's blood are cultured in culture media outside the body then the lymphocytes are implanted with functioning ADA cDNA and returned to the patient. In this procedure, such genetically altered lymphocytes must be infused on a regular basis. If a gene derived from bone marrow cells that produces ADA is injected into cells during the early embryonic stages, it might lead to a permanent cure.

 Molecular Diagnosis: Conventional methods of diagnostics, such as serum or urine analysis, are incapable of detecting disease-causing bacteria or viruses early. The following methods can be used for early diagnosis:

(i) rDNA technology: The method uses the extraction of a gene, cloning it and then amplifying it by PCR. The method uses polymerases, ligases, vectors, and hosts. 

(ii) PCR : Symptoms of illness develop only after the pathogen concentration is sufficiently raised. Amplification of nucleic acid by PCR can identify low concentrations of bacteria and viruses. The technique detects gene mutations in cancer patients. In suspected AIDS patients, PCR is regularly employed to detect HIV. The PCR method can also be used to detect genetic disorders also.

 

(iii) ELISA: The antigen-antibody interaction concept underpins ELISA. Pathogen infection can be identified by identifying antigens such as proteins, glycoproteins, and so on, or by detecting antibodies synthesised against the pathogen. 

Transgenic Animals

Transgenic animals are those that have had their DNA manipulated in order to possess and express a foreign gene. There have been transgenic mice, rats, rabbits, pigs, sheep, cows, and fish developed. 

What is the need of creation of transgenic animals? 

• To study gene regulation and its effect on normal functions of the body. 

• Understand how the genes contribute to the development of a disease. 

• Transgenic animals help in production of useful biological products. E.g. human protein (α-1-antitrypsin) used to treat emphysema. 

• The first transgenic cow, Rosie, produced human protein-enriched milk (alpha-lactalbumin – 2.4 gm / litre). 

• Such animals are useful in the testing of vaccines before human trials. 

Note: Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s. 

Note: Transgenic mice are being used to test the safety of the polio vaccine.

Ethical Issues 

The India government has established bodies such as the GEAC (Genetic Engineering Approval Committee) to make judgements on the legitimacy of GM research and the safety of integrating GM-organisms into public services. 

Biopatent: A patent is government-granted protection that allows an inventor to restrict others from commercialising his creation. 

 Through the US Patent and Trademark Office, an American corporation obtained patent rights on Basmati rice in 1997. This ‘new’ variety of Basmati had actually been derived from Indian farmer’s varieties. Indian Basmati was crossed with semi-dwarf varieties and claimed as an invention or a novelty. The patent extends to functional equivalents, implying that other people selling Basmati rice could be restricted by the patent. This enabled the business to offer a "new kind of Basmati" in the United States and elsewhere. 

Biopiracy: It is the phrase used to describe the utilisation of bio-resources by multinational corporations and other organisations without legal licence from the nations and people involved and without compensation