12th Class Biology Biotechnology : Principles And Processes

  • question_answer 10)
    Describe briefly the following: (a) Origin of replication (b) Bioreactors (c) Down streaming process  


    (a) Origin of replication (ori): One of the major components of a plasmid is a sequence of bases where replication starts. It is called origin of replication (on). This is a specific portion of plasmid genome that serves as start signal for self-replication (to make another copy of itself). Any piece of DNA when linked to this sequence can be made to replicate within the host cells. This property is used to make a number of copies of linked DNA (or DNA insert). (b) Bioreactors: Bioreactors are vessels in which raw materials are biologically converted into specific products by microbes, plant and animal cells and their enzymes. They are allowed to synthesize the desired proteins which are finally extracted and purified from cultures. Small volume cultures are usually employed in laboratories for research and production of less quantities of products. However, large scale production of the products is carried out in ' bioreactors'. The most commonly used bioreactors are of stirring type that have a provision for batch culture or continuous culture. In continuous culture, the culture medium is added and the product is taken out continuously. (c) Downstream processing: After the formation of the product in the bioreactors, it undergoes through some processes before a finished product is ready for marketing. The processes include separation and purification of products which are collectively called the downstream processing. The product is then subjected to quality control testing and kept in suitable preservatives. A proper quality control testing for each product is also needed. The downstream process and quality control test are different from product to product.  

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