Biotechnology: Principle & Processes Test 3

Biotechnology, often abbreviated to biotech, is the area of biology that uses living processes, organisms or systems to manufacture products or technology intended to improve the quality of human life. Depending on the technology, tools and applications involved, biotechnology can overlap with molecular biology, bionics, bioengineering, genetic engineering and nanotechnology.

S. Cohen and H. Boyer constructed the first recombinant DNA using antibiotic resistance genes present on the plasmid of drug resistance strains of E. coli. This gene was linked to the native plasmid of Salmonella typhimurium. Their work discovered rRNA technology as multistep process that includes cutting of DNA at precise locations using restriction endonucleases, selection of a small molecule of DNA that can self-replicate, called cloning vectors, insertion of DNA with gene of interest in vector DNA to make recombinant DNAs, insertion of recombinant DNA to a host cell that will provide the enzymatic machinery for DNA replication and selection of host cells that contain recombinant DNA.

A restriction endonuclease is an enzyme that cuts the DNA molecule at, or near to, a specific nucleotide sequence to produce discrete DNA fragments that can be separated by gel electrophoresis.

A vehicle DNA is required to carry foreign DNA to generate a recombinant construct so that it should allow easy amplification of chimeric DNA in host. Vehicle DNA used for this purpose in genetic engineering is known as ‘vector’.    
     
Criteria of a good vector : The vector DNA has a two main responsibility: (1) ability to carry foreign DNA, (2) ability to replicate in the host. Hence to fulfil these responsibility, a number of properties are desirable. 

Biolistics or gene gun is a direct or vectorless way used to introduce alien DNA into host cells. In this method of gene transfer, high velocity micro-particles of gold or tungsten, coated with DNA are bombarded on the plant cells. 

Escherichia coli and Agrobacterium tumefaciens are the microbes found to be very useful in genetic engineering. 
E. coli is a motile, gram negative, rod shaped bacterium which is a normal inhabitant of human colon. It is most extensively used in bacterial genetics and molecular biology.
Agrobacterium tumefaciens is a soil bacterium. It has Ti plasmid (Tumour inducing plasmid) and it can be used for the transfer of a desired gene in dicot plants.

Gel electrophoresis is used to separate macromolecules like DNA, RNA and proteins. DNA fragments are separated according to their size. Proteins can be separated according to their size and their charge (different proteins have different charges).

Recombinant DNA technology is joining together of DNA molecules from two different species that are inserted into a host organism to produce new genetic combinations.

A vector is a DNA molecule used as a vehicle to transfer foreign genetic material into desired cell.
the tRNA is synthesised in the nucleus on a DNA molecule template. Only 0.025% of total DNA content codes for tRNA.