BIOTECHNOLOGY AND ITS APPLICATIONS

 

The critical areas of biotechnology are:

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

BIOTECHNOLOGICAL APPLICATIONS IN AGRICULTURE:

  • Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO).

  • Advantages of Genetic Modification in plants.
    • Made crops more tolerant to abiotic stresses (cold, drought, salt, heat)
    • Reduce reliance on chemical pesticides (pest resistant crop)
    • Helped to reduce post harvest losses.
    • Increased efficiency of mineral usage by plants.
    • Enhanced nutritional values of food e.g. vitamin A enriched rice.

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.
  • These proteins are present in inactive protoxin form, but become active toxin in the alkaline pH of insect gut.
  • 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 insect
  • Specific Bt toxin genes were isolated form B. thuringiensis and genetically transferred to several plants such as cotton.
  • Crystal proteins are produced by a gene called cry in B. thuringiensis.
  • The protein coded by genes cryIAc and cryIIAb control the cotton bollworms.
  • The protein coded by gene cryIAb controls corn borer.

Pest resistant plants:

  • Several nematodes parasitize a wide variety of plants and animals including human beings.
  • A nematode Meloidegyne incognitia infects the root of tobacco plants and causes a great reduction in yield.
  • Strategy based on RNA interference (RNAi) prevents this infestation.
  • Process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of mRNA

Steps of RNA interference:

  • Double stranded RNA is produced endogenously or exogenously.
  • Using Agrobacterium vectors nematode specific genes were introduced into the host plant (tobacco plant).
  • Introduction of DNA produces both sense and antisense RNA in the host.
  •  These two RNA’s being complementary to each other formed a double stranded (dsRNA) that initiated RNAi.
  • The dsRNA injected into the host plant from outside called exogenous dsRNA.
  • The dsRNAs are cleaved into 21-23 nt segments (“small interfering RNAs”, or siRNAs) by an enzyme called Dicer.
  • siRNAs are incorporated into RNA-induced silencing complex (RISC) 
  • Guided by base complementarity of the siRNA, the RISC targets mRNA for degradation.
  • The consequence was that the parasite could not survive in a transgenic host.

BIOTECHNOLOGICAL APPLICATIONS IN MEDICINE:

  • Biotechnology enables mass production of safe and more effective therapeutic drugs.
  • Recombinant therapeutics does not induce unwanted immunological responses as is common in case of similar products isolated from non-human sources.
  • At present around 30 recombinant therapeutics, approved for human-use.

Genetically Engineered Insulin:

  • Taking insulin at regular interval of time is required for adult-onset diabetes.
  • Previously the source of insulin was the slaughtered cattle and pigs.
  • This insulin caused allergy in some patients.
  • Each insulin made of two short polypeptide chains; chain A and chain B that are linked together by disulphide linkage.
  • Insulin synthesized in pancreas as pro-hormone which is a single polypeptide with an extra stretch called C-peptide.
  • C-peptide is removed during matured insulin.
  • In 1983 Eli Lilly an American company 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.
  • Chain A and chain B produced separately, extracted and combined by creating disulfide bonds to form mature human insulin.

 

CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]