The technology that is used to alter the genetic make up of living cells by direct or indirect interference within the genome is called Genetic engineering.It is mainly concerned with the gene repair or gene recombining.
RECOMBINANT DNA TECHNOLOGY:
The hybrid DNA produced by the combination of a segment of DNA from one organism with another in a test tube is called Recombinant DNA.
Paul Berg in 1972 successfully transplanted the DNA of virus SB-40 in a E.coli cell.As a result,an organism was produced which have the combination of characters of SB-40 virus as well as E.coli bacteria.This technology was called recombinant DNA technology.
This has become with the discovery of 2 groups of enzyme:Restriction endonuclease and DNA ligase.
The three method that are used for DNA recombinant technology are as follows:
1)ADDITION OF NEW DNA SEGMENT AT THE END OF 2 STRAND OF DNA:
Some bases i.e TTTT are added to free end of DNA strand and complementary bases AAAA are added to free end of another DNA strands.Both DNA strands are all added to recombine the bases of added,joined together by Hydrogen bond to form recombinant DNA.The enzyme terminal transperase catalysis this process.
2)GENE TRANSFER WITH PLASMID:
This process involves the plasmid and two enzyme called restriction endonuclease and DNA ligase.
Plasmids are the intra segment of DNA present in the cytoplasm of mostly in bacterial cell.During this process,enzyme restriction endonuclease which acts as knife ,cut the plasmid DNA leaving a sticky ends in both the sides of gene segment.The desired gene segment is then inserted into the cut portion in plasmid and treated with ligase.DNA ligase can completely seal the gap making it circular DNA plasmid that contain the plasmid gene as well as piece of foreign DNA segment.
3)CLONING OF DNA:
Bacteria are often used as a host for multiplication of recombinant DNA.Recombinant plasmid is introduced in the bacterial cell.The bacterial cell take up the DNA through transformation process.Bacteria with recombinant plasmid multiply and form a colony.Such identical cells are called as clone as a result of cloning.
APPLICATION OF GENETIC ENGINEERING:
Genetic engineering has unlimited scopes.The broad areas of its application are listed below:
This includes fundamental understanding of control of genes expression,differentiation of cells,organisation of chromosome,structure of gene and study of viral genome.
Genetic engineering includes manufacture of human proteins,products of medical importance i.e insulin,haemoglobin,growth hormones,specific antibodies etc.
Genetic engineering is mainly used in the protection and production of crops plants.It produces disease resistance variety of plants and also increase the yield of plants.
Production of organic substance like ethanol,proteins,vitamins by genetic improvement of micro organisms.
5)IN ENVIRONMENTAL POLLUTION:
Environment pollution can be controlled by producing micro organism capable of quicker break down of waste.
6)CREATION OF TRANSGENIC ANIMALS:
The animals with inserted desired genes in germ line is called transgenic animal.Genetic engineering can be used to produce transgenic animals.
POSSIBLE DANGERS OF GENETIC ENGINEERING:
1)Genetic engineering may resolve into new kind of disease.
2)Accidental production and escape of potentially dangerous organism may cause environmental pollution.
3)Possibility of producing germs which are resistance to known antibiotics to be used for biological welfare.
4)New type of organism can be created accidentally which may create different types of diseases in the society.
5)There is risk of creation of drug resistance germs and out break diseases against which there is no known prevention.
6)There may be tendency to produce monsters, robots or a dictator who may decide to create thousands of sub human creature of specific purpose.
HUMAN GENOME PROJECT:
It is an international effort to map the various types of human chromosomes and to sequence their 3 billion base pair.It involves preparing a separate genetic linkage map and a physical map for each chromosome.Then the two maps will be synchronized.This project is headed by Prof. Watson of USA.
The human genome is beleived to have 100000 genes.Each chromosome has been assigned at most about 200 genes.the particular human chromosomes can be recognized because each one has a distinctive patterns.The genetic map of chromosome will tell the sequence of genes on what chromosomes.The main objective of this project is to find out human genes and thier character.once the gene for any character are known,gene therapy in human can be possible.
Insertion of normal genes to rectify genetic deficiency is called gene therapy.
It helps to replace defective genes with normal genes in human.
All the genes of an organism can be identified,multiplied and preserved in the set of clones.The various clones representing all the genes are referred as gene library.
Vectors are the agent required for cloning of genes.
The foreign DNA fragments are inserted into the vectors DNA for multiplication and production of clone.
Cosmids are hybrid vector derived from plasmids and contains cos site.
These are excellent tools for clonning large DNA fragments.
Plasmids are the intra segment of DNA present in the cytoplasm in the bacterial cell.
They are the keys clonning vector.
Immunity is defined as the ability of body to resist the disease.
Selection of parents traits in order to manipulate the heriditary characters of organism is called control breeding.
Hybridoma is the hybrid cell produce by the cross between tumor cell and normal antibody producing lymphocyte and the technique called hybridoma technology.
A particular antibody produced by one of the numerous similar cells obtained from single parent cell is called monoclonal antibody.
They are used to detect antibody within a mixture and identifying blood group.
The plants with inserted desired genes into their germ line is called transgenic plants.
Disease resistant varieties of plants can be produced by theis technique.
11)DNA FINGERPRINTING(GENETIC FINGER PRINTING):
A technique used to identify a person from a sample of their DNA is called DNA fingerprinting.
It is especially used to identify whether a person is criminal i.e has committed crime or not.
12)DNA PROBE(GENE PROBE):
A single stranded DNA or RNA used in genetic engineering to search for a particular gene is called DNA probe.
Inferon is an antiviral agent used as a drug against viruses.
Recombinant DNA technology is used to develop inferon against viral disease.