What is downstream processing ?

Hint:Recombinant DNA technology is the process of joining two DNA fragments from two species and insertion of this combined DNA into host for multiplication and production of desired products .It has several steps and the final step is down stream processing.

Complete answer:
Downstream processing refers to the process of purification and separation of products of recombinant DNA technology. Suitable preservatives are added to the product .Proper quality check is maintained. In the case of drugs and medicines proper clinical trials are conducted. Pure homogeneous products are obtained which are free of other molecules. After all this desired quality products are obtained and released into the market for public usage.
Process of downstream processing are :
1.Removal of insolubles: obtaining particulate free liquid using filtration , centrifugation, sedimentation , precipitation etc.
2.Product isolation: Removal of substances having different properties than desired product using ultrafiltration , solvent extraction etc.
3.Product purification: separation of substances having very close chemical and physical properties with desired product using chromatography and crystallization.
4.Product polishing: packaging of product.

Additional Information:
Recombinant DNA technology consists of steps such as:
1.Isolation of genetic material.
2.Cutting of DNA at specific sites with the help of restriction enzymes.
3.Extraction and amplification of genes of interest.
4.Insertion of recombinant DNA in the host cell.
5.Downstream processing.

Note:
Downstream streaming is the last part of recombinant DNA technology which includes purification and separation of the desired product.