Tag: biotechnology: general introduction

A xenobiotic is a foreign chemical substance found within an organism that is not normally naturally produced by or expected to be present within that organism. The term xenobiotics is often used in the context of pollutants such as dioxins and polychlorinated biphenyls and their effect on the biota, because xenobiotics are understood as substances foreign to an entire biological system, i.e., artificial substances, which did not exist in nature before their synthesis by humans. 

Klebsiella pneumoniae is a Gram-negative, non-motile, encapsulated, lactose-fermenting, facultative anaerobic, rod-shaped bacterium. It naturally occurs in the soil, and about 30% of strains can fix nitrogen in anaerobic conditions.

The basic process of recombinant DNA technology revolves around the activity of DNA in the synthesis of protein. By intervening in this process, scientists can change the nature of the DNA and of the gene make-up of an organism. By inserting genes into the genome of an organism, the scientist can induce the organism to produce a protein it does not normally produce. The genes used in DNA technology are commonly obtained from host cells or organisms called as gene libraries. A gene library is a collection of cells identified as harbouring a specific gene. For example, E. coli cells can be stored with the genes for human insulin in their chromosomes. Vaccines represent another application of recombinant DNA technology. For instance, the hepatitis B vaccine now in use is composed of viral protein manufactured by yeast cells, which have been recombined with viral genes. 

Genetic engineering, also called as genetic modification, is the direct manipulation of an organism's genome using biotechnology. New DNA is inserted in the host genome by first isolating and copying the genetic material of interest using molecular cloning methods to generate a DNA sequence, or by synthesizing the DNA and then inserting this construct into the host organism. Genetic engineering techniques have been applied in numerous fields including research, agriculture, industrial biotechnology, and medicine. Enzymes used in laundry detergent and medicines such as insulin and human growth hormone are now manufactured in GM cells, experimental GM cell lines and GM animals such as mice or zebrafish are being used for research purposes, and genetically modified crops have been commercialized.

In 1973 Herbert Boyer, of the University of California at San Francisco, and Stanley Cohen, at Stanford University, reported the construction of functional organisms that combined and replicated genetic information from different species. Their experiments dramatically demonstrated the potential impact of DNA recombinant engineering on medicine and pharmacology, industry and agriculture.

Bacteria were the first organisms to be genetically modified. Plasmid DNA containing new genes can be inserted into the bacterial cell and the bacteria will then express those genes. These genes can code for medicines or enzymes that process food and other substrates.

Tissue plasminogen activator is a clot-dissolving enzyme that is produced naturally by cells in the walls of blood vessels and catalyzes the conversion of plasminogen to plasmin. A preparation of this enzyme is produced by genetic engineering and used to dissolve clots blocking coronary arteries in heart attack and cranial arteries in certain cases of stroke.

Genetic engineering is possible because all organisms are based on the same genetic code. DNases which act on specific positions or sequences on the DNA are called as restriction endonucleases. The sequences which are recognised by the restriction endonucleases or restriction enzymes (RE) are called as recognition sequences restriction sites. These sequences are palindromic sequences. Different restriction enzymes present in different bacteria can recognize different or same restriction sites but they will cut at two different points within the restriction site. No two restriction enzymes from a single bacterium will cut at the same restriction site. 

Genetic engineering is the process of replicating a specific set of genes from a strand of DNA. It is the process of using gene cloning and other genetic manipulation tools to achieve isolate specific genes.