12th Zoology

Restriction enzymes – Recombinant DNA Technology

Restriction enzymes – Recombinant DNA Technology

The restriction enzymes cut the DNA molecule around the point of
symmetry. The above palindrome sequence is recognized by the
restriction enzyme derived from Escherechia coli, called EcoR1. It cuts the
DNA molecule into discrete fragment with staggered cut ends.

Recombinant DNA

The foreign DNA fragment isolated is made to recombine with the
plasmid DNA which is cleaved by the same restriction endonuclease. The
recombination of the two DNAs is effected by the DNA ligase enzyme. The
product formed is called recombinant plasmid or recombinant DNA.

Molecular cloning

The recombinant DNA must be introduced into a host cell, within
which it may replicate freely. Escherechia coli has been employed as a
suitable host to the above. Alongside, with the multiplication and growth of
the bacterium in the medium, copies of rDNA are also produced. In
molecular cloning, besides E.coli other microbes that have been employed
include Bacillus subtilis, Strptomyces sp., Saccharomyces cerevisieae etc.
When the rDNA copies are introduced into the host cells, (E. coli) a
few thousand of rDNA pieces may enter the cells. These cells are called
transformed cells. Each transformed cell grows a colony of its own in which
every member is genetically alike. These colonies are then distinguished and
recultured separately.

From the recultured colonies, the recombinant DNA is extracted from
lysed cells, purified and used. The first gene was cloned in 1973 by Hebert
Bayer and Stanely cohen of Stanford University, California of USA.

Application and Uses of Recombinant DNA Technology

1. Genetic engineering/recombinant DNA technology has enabled the
understanding of structure of eukaryotic genes and their components.
2. Genetically engineered bacteria are employed to synthesize certain vital
life saving drugs, hormones and antibiotics eg., Antiviral / anticancer interferons
; human growth hormone (HGH) somatostatin, etc.

3. Through recombinant DNA technology, the genotypes of plants are altered.
New transgenic plants which are resistant to diseases and pest attack
have been produced.
4. Genetic defects in animals as well as human could be corrected through
gene therapy.
5. Genetically engineered bacteria are called superbugs. Superbugs can degrade
several aromatic hydrocarbons, at the same time. They are employed
in clearing oil spills in the ocean. Thus these are used in pollution abatement.
The super bug was produced first by an Indian researcher Anand
Chakrabarthy in USA. He developed a strain of Pseudomonas bacterium to
clear up oil spills. The above superbug can destroy octanes, xylenes camphors
and toluenes.


Related Topics in Zoology:

Bio Zoology All Important Topics

  1. MODERN GENETICS Introduction and Scope

  2. Human Genetics – Karyotyping

  3. Karyotyping of Human chromosomes

  4. Genetic Engineering

  5. Tools Of Genetic Engineering

  6. Restriction enzymes – Recombinant DNA Technology

  7. DNA – Segmenting / Fragmenting

  8. Genetic Diseases

  9. Human Genome Project (HGP)

  10. Cloning

  11. Transgenic organisms

  12. Gene Therapy

  13. Bioinformatics

  14. Scope of Genetic Engineering – Scope of Bioinformatics

  15. Database

  16. Genome sequencing

  17. Protein structure


    1. Human population and explosion

    2. Population Explosion

    3. Growing Population and Environmental impacts

    4. Global warming – Green house effect

    5. Ozone layer depletion

    6. Prevention and Effect of Ozone depletions

    7. Waste management – Classification

    8. Management of hazardous wastes

    9. Management of non hazardous wastes

    10. Waste water treatment and management

    11. Biodiversity

    12. Conservation of Biodiversity

    13. Characteristics of a Bioreserve

    14. Energy crisis and its environmental impact

    15. Steps to be taken to resolve energy crisis

    16. Environmental impacts of Power Sources

    17. Poverty and environment

    18. Fresh water crisis and management

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