November 30, 2021

Biotechnology and its Applications Class 12 | Term 2 | Biotechnology

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Biotechnology and its Applications Class 12 | Term 2 | Biotechnology

Critical Areas of Research

Biotechnology has three critical research areas:

Providing the best catalyst in the form of improved organisms usually a microbe or pure enzyme.
Creating optimal conditions through engineering for catalyst to act.
Downstream processing technologies to purify the protein/organic compound.

Applications of Biotechnology in Agriculture

Methods to Increase Food Production

There are three options for increasing food production

Agro-Chemical based agriculture
Organic agriculture
Genetically engineered crop-based agriculture

The green revolution has increased the yield of crops due to

Use of improved crop varieties.
Use of agrochemicals such as fertilizers and pesticides.

However , further increase in crop yield with existing varieties of crops is not possible using conventional methods of breeding.
Also, the agrochemicals cause soil and water pollution and are expensive for the farmers.
In order to overcome these problems , genetically modified organisms were used.

Genetically Modified Organisms (GMO) or Transgenic Organisms.

These are the plants, bacteria, fungi and animals whose genes are altered by manipulation.

Advantages of Genetic Modification in Plants

(i) Tolerant to abiotic stresses (cold, drought, salt, heat)

(ii) Reduces reliability on chemical pesticides.

(iii) Reduces post-harvest losses.

(iv) Increases efficiency of mineral usage by plants.

Application of Biotechnology in the Production of Pest Resistant Plants

Pest resistant plants decrease the amount of pesticides used.
Bt toxin is produced by a bacterium called Bacillus thuringiensis.
Bt toxin gene has been cloned from bacteria in plants to provide resistance to insects to produce bio pesticide without the need for insecticides.
Examples – Bt cotton , Bt corn , rice , tomato , potato and soyabeans etc.

Bt Cotton

Bt cotton is created by using some strains of a bacterium, Bacillus thuringiensis (Bt is short form,).
This bacterium produces proteins that kill certain insects such as lepidopterans (tobacco, budworm and armyworm), coleopterans (beetles) and dipterans (flies and mosquitoes).
Thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.
Bt toxin protein exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut, which solublise the crystals.
The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis leading to death of an insect.
Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into several crop plants as cotton.
Most Bt toxins are insect-group specific. The toxin is coded by a gene named cry, g. the proteins encoded by the genes cry IAc and cry IIAb control the cotton bollworms and cry IAb controls corn borer.

Nematode Resistance in Tobacco Plants

A nematode Meloidogyne incognita infects the roots of tobacco plants, which reduces the production of tobacco.
RNA interference (RNAi) process is used for cellular defence. It involves silencing of a specific mRNA due to a complementary dsRNA. It occurs in all eukaryotic organisms as a method of cellular defense.
dsRNA binds and prevents translation of the mRNA (silencing).
The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.
Agrobacterium vectors are used to introduce nematode-specific genes into the host plant. It produces both sense and anti-sens^e RNA in the host cells.
These two RNAs are complementary to each other and forms a double stranded RNA (rfsRNA) that initiate RNAi and hence, silence the specific mRNA of the nematode.
The parasite cannot survive in transgenic host, expressing specific interfering RNA. The transgenic plant thus, gets itself protected from the parasite.

Applications in Medicine

The recombinant DNA technology helps for the mass production of safe and more effective therapeutic drugs.
The recombinant therapeutics does not induce unwanted immunological responses as is common in case of similar products isolated from non-human sources.
At present, there are about 30 recombinant therapeutics that have been approved for human – use .
In India, 12 of these are being marketed.

Genetically Engineered Insulin

Genetically engineered insulin leads to sufficient availability of insulin for the management of adult-onset diabetes.
(a) Insulin used for diabetes was earlier extracted from the pancreas of slaughtered cattle and pigs. This caused allergy or other reactions in some patients.
(b) Insulin consists of two short polypeptide chains, i.e. chain-A and B, linked together bridges.

(c) In mammals, insulin is synthesised as a prohormone (needs to be processed before it becomes a fully mature and functional hormone) which contains an extra stretch called the C-peptide.
(d) C-peptide is not present in the mature insulin $nd is removed during maturation into insulin. Thus, the main challenge for the production of insulin using rDNA techniques was getting insulin assembled into a mature form.
(e) Eli Lilly an American company in 1983, prepared two DNA sequences corresponding to A and B-chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains-A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin.
II. Production of vaccines through genetic engineering such vaccines are called recombinant vaccines also called ‘subunit vaccines’ or ‘second generation vaccines’, e.g hepatitis-B. These are of two types:
(a) Protein vaccines use of specific protein produced by rDNA in vaccine.
(b) DNA vaccines use of genetically engineered DNA to be injected as vaccine to produce an immunological response.
Hepatitis vaccine contains the viral envelope protein, hepatitis-B surface antigen (HB₈ Ag). This gene is isolated from yeast vectors.
Some protein coding genes isolated from pathogens are also incorporated and expressed in plants produce antigens and are also called edible vaccines.

Gene Therapy

Gene Therapy is a collection of methods that allows correction of gene defects, diagnosed in a child or embryo.
(a) Genes are inserted into a person’s cells and tissues to treat a disease.
(b) Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function and compensate for the non-functional gene.
(c) First gene therapy was given to a four year old girl with Adenosine Deaminase (ADA) deficiency by M Blease and WF Andresco in 1990s

ADA is caused due to the deletion of the gene for adenosine deaminase.<
In some children, ADA deficiency can be cured by bone marrow transplantation and enzyme replacement therapy, but they are not completely curable.
(d) Steps involved are as follows:
In first step of gene therapy, lymphocytes from the blood of the patient are grown in a culture outside the body.
A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient.
As these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes.
If the gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.
Some other diseases that can be treated by gene therapy are haemophilia, cystic fibrosis, Parkinson’s disease, etc.

Molecular Diagnosis

Molecular Diagnosis helps to solve the problem of early diagnosis and treatment of diseases.
(a) Using conventional methods of diagnosis (serum and urine analysis), early detection of diseases is not possible.
(b) To overcome this problem, some molecular diagnosis techniques were developed that provide early detection of diseases.

These are as follow;

(i)Polymerase Chain Reaction (PCR) helps in early detection of diseases or pathogens by the amplification of their nucleic acid.

(ii) Recombinant DNA technology is a modern molecular diagnostic technique.

(iii) Enzyme Linked Immuno Sorbent Assay (ELISA) is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised against the pathogen.

Transgenic Animals

These are the animals whose genome has been altered by introduction of an extra gene by manipulation.
In other words, animals that have had their DNA manipulated to possess an extra gene are known as transgenic animals.
Examples- transgenic rats , rabbits , pigs , sheep , cows and fish.
Over 95% of all existing transgenic animals are mice.

Advantages of Transgenic Animals

Transgenic animals can be used as a model system to study diseases. They are specially designed to study the role of genes in the development of certain diseases. Moreover, in order to devise a cure for these diseases, the transgenic animals are used as model organisms. For example, transgenic models have been used for studying diseases such as Alzheimer’s and cancer.
Transgenic animals are useful in the production of vaccines. They are used as model organisms for testing the safety of vaccines before they are injected into humans.
Transgenic animals have been useful in developing various useful biological products. Biological products can be created by the introduction of the portion of DNA or genes that code for a particular product such as human protein (alpha-1-antitrypsin) which is used to treat emphysema.
In transgenic animals, a foreign gene is introduced. It leads to an alteration of the growth factor. Hence, these animals facilitate the study of gene regulation and their effect on the everyday functions of the body.

ETHICAL ISSUE

Genetic modification may cause unpredictable results when such organisms are introduced into the ecosystem.
Therefore, Indian Government has set up organization like GEAC ( Genetic engineering approval committee).
Certain companies have got patents for products and technologies that make use of the genetic materials, plants etc. that have been identified , developed and used by farmers .
For eg. Basmati rice , herbal medicines life turmeric , neem etc.

Basmati rice

It has unique aroma and flavour.
India has 27 documented varieties of Basmati.
In 1997 , an American company got patent rights on Basmati rice through the US Patent and Trademark Office . This allowed the company to sell a new variety of Basmati.
This had actually been derived from Indian farmer’s varieties.
Indian Basmati was crossed with semi- dwarf varieties and claimed as movelty.
Other people selling Basmati rice could be restricted be the patent .

Biopiracy

Biopiracy is the practice of exploiting naturally occurring genetic or biochemical material in commerce. Most indigenous people have traditional knowledge that mainly includes genetic diversity and natural environment biological features from generation to generation.

Some nations are developing legislation to avoid such illegal exploitation of their bio-resources and traditional knowledge. The second amendment to the Indian Patents Bill has recently been approved by the Indian Parliament. It takes account of such issues, including the terms of the patent, the emergency provisions, the research and development initiative.

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