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Biotechnology And Its Applications

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Biotechnology and Its Applications PDF Notes, Important Questions and Formulas

Biotechnology and Its Applications

INTRODUCTION

"BIOTECHNOLOGY may be defined as use of micro-organism, animals, or plant cells or their products to generate different products at industrial scale and services useful to human beings." A powerful industry based on microbes has been developed in recent time. A careful selection of microbial strains. improved method of extraction and purification of the product, have resulted in enomous yields.

The use of living organisms in systems or process for the manufacturer of useful products. It may involve algae, bacteria, fungi, yeast, cells of higher plants & animals or subsystems of any of these of isolated components from living matter.

Old biotechnology is based on the natural capabilities of micro-organisms.

e.g. formation of Citric acid, production of penicillin by Penicillium notatum

New biotechnology is based on Recombinant DNA technology.

e.g. Human gene producing Insulin has been transferred and expressed in bacteria like E. coli.

The European Federation of Biotechnology (EFB) has given a definition of biotechnology that encompasses both traditional view and modern molecular biotechnology. The definition given by EFB is as follows: The integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services'.

Genetic engineering also referred as ‘recombinant DNA technology’ or ‘gene splicing’ is one kind of biotechnology involving manipulation of DNA.

– It deals with the isolation of useful genes from a variety of sources and the formation of new combinations of DNA (recombinant DNA) for repair, improvement, perfection and matching of a genotype.

– Thus, genetic engineering may be defined ‘as a technique for artificial and deliberately modifying DNA (gene) to suit human needs’.

–  In genetic engineering breakage of DNA molecule at two desired places is done with the help of restriction endonuclease to isolate a specific DNA segment and then insert it in another DNA molecule at a desired position.

–  The new DNA molecule is recombinant DNA and the technique called genetic engineering. Genetic engineering aims at adding, removing or repairing of a part of genetic material. Genetic engineering can be used to improve the quality of human life.

Paul bergh (Father of genetic engineering). He transferred gene of SV-40 virus (Simian virus) in to E.coli with the help of λ – phage (Nobel prize – 1980) The concept of genetic engineering was the outcome of two very significant discoveries made in bacterial research These were -

  1. Presence of extrachromosomal DNA fragments called plasmids in the bacterial cell, which replicate along with chromosomal DNA of the bacterium.
  2. Presence of enzymes restriction endonucleases which cut DNA at specific sites. These enzymes are, therefore, called ‘molecular scissors’.

TOOLS AND TECHNIQUES OF GENETIC ENGINEERING

Genetic engineering involves cutting of desired segments of DNA and pasting of this D.N.A in a vector to produce a recombinant DNA (rDNA). The ‘biological tools’ used in the synthesis of recombinant DNA include enzymes, vehicle or vector DNA, passenger DNA and alkaline phosphatases.

Enzymes. A number of specific kinds of enzymes are employed in genetic engineering. These include lysing enzymes, cleaving enzymes, synthesising enzymes and joining enzymes.

  1. Lysing enzymes. These enzymes are used for opening the cells to get DNA for genetic experiment. Bacterial cell wall is commonly dissolved with the help of lysozyme.
  2. Cleaving enzymes. These enzymes are used for DNA molecules. Cleaving enzymes are of three types; exonucleases, endonucleases and restriction endonucleases.

 

  1. Exonucleases cut off nucleotides from 5' or 3' ends of DNA molecule.
  2. Endonucleases break DNA duplex at any point except the end.
  3. Restriction endonucleases cleave DNA duplex at specific points in such a way that they come to possess short single stranded free ends.

For example, a restriction endonuclease ECOR-l (from Escherichia coli) recognizes the base sequence GAATTC/CTTAAG in DNA duplex and cleaves its strands between G and A.

Restriction enzymes are obtained from bacteria. They are useful to bacteria because the enzyme bring about fragmentation of viral DNA without affecting the bacterial genome. This is an adaptation against bacteriophages. Restriction enzyme (Eco R-I) was discovered by Arber, Smith & Nathans (1978 Nobel prize).

These enzymes exist in many bacteria beside cleavage some restriction endonuclease, also have capability of modification. Modification in the form of methylation, by methylation the bacterial DNA modifies and therefore protects it's own chromosomal DNA from cleavage by these restriction enzymes.

Restriction enzymes are used in recombinant DNA technology because they can be used in vitro to recognize and cleave within specefic DNA sequence typically consisting of 4 to 8 nucleotides. This specific 4 to 8 nucleotide sequence is called restriction site and is usually palindromic, this means that the DNA sequence is the same when read in a 5'-3' direction on both DNA strand

BIOTECHNOLOGY: AND IT’S APPLICATIONS

INTRODUCTION

The applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production. Three critical research areas of biotechnology are:

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

Let us now learn how human beings have used biotechnology to improve the quality of human life, especially in the field of food production and health.

 2.  BIOTECHNOLOGICAL APPLICATIONS IN AGRICULTURE

Let us take a look at the three options that can be thought for increasing food production

  1. agro-chemical based agriculture;
  2. organic agriculture; and
  3. Genetically engineered crop based agriculture.

The Green Revolution succeeded in tripling the food supply but yet it was not enough to feed the growing human population. Increased yields have partly been due to the use of improved crop varieties, but mainly due to the use of better management practices and use of agrochemicals (fertilisers and pesticides).

However, for farmers in the developing world, agrochemicals are often too expensive, and further increases in yield with existing varieties are not possible using conventional breeding. Is there any alternative path that our understanding of genetics can show so that farmers may obtain maximum yield from their fields? Is there a way to minimise the use of fertilisers and chemicals so that their harmful effects on the environment are reduced? Use of genetically modified crops is a possible solution.

Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called genetically Modified Organisms (GMO). GM plants have been useful in many ways. Genetic modification has:

  1. Made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
  2. Reduced reliance on chemical pesticides (pestresistant crops).
  3. Helped to reduce post-harvest losses.
  4. Increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil).
  5. Enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice.

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

Some of the applications of biotechnology in agriculture that you will study in detail are the production of pest resistant plants, which could decrease the amount of pesticide used. But toxin is produced by a bacterium called Bacillus thuringiensis (Bt for short). Bt toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides; in effect created a bio-pesticide. Examples are Bt cotton, Bt corn, rice, tomato, potato and soyabean etc.

Bt Cotton:

Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. Why does this toxin not kill the Bacillus?

Actually, the Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals.

The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect. Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into the several crop plants such as cotton. The choice of genes depends Upon the crop and the targeted pest, as most Bt toxins are insect-group specific. The toxin is coded by a gene named cry. There are a number of them, for example, the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms that of cryIAb controls corn borer.

B.     Pest Resistant Plants:

Several nematodes parasitise a wide variety of plants and animals including human beings. A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi). RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary ds RNA molecule that binds to 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. Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. The introduction of DNA was such that it produced both sense and anti-sense RNA in the host cells.

 

 

 

                 

 

 

 

 

 

 

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