Downstream processing - class-XII

After the formation of the product in bioreactors, it undergoes through some processes before a finished product is ready for marketing. The processes include separation and purification of products which is collectively called as downstream processing.

When bacteria (a prokaryote) is engineered to express a gene from a
plant (an eukaryote), a slightly  different approach is used. Eukaryotic
genes have both exons and Introns which are transcribed into the
primary transcript. Primary transcript is then processed by splicing
(removal of introns and joining of exons), capping and tailling to
produce functional mRNAs. This functional mRNA is then expressed into
proteins. Prokaryotes lack such machinery, hence expression of an
eukaryotic DNA becomes difficult in prokaryotic cells. Therefore,
scientists prepare cDNA from the functional nRNA (without introns) using
reverse transcriptase. This DNA is incorporated into bacteria (or
another prokaryotic cell) for expression of plant gene. Such foreign
gene synthesises a protein with the same sequence of amino acids as in
the plant, and therefore the proteins have the same structure and
function as in the plant.

The animals which carry foreign genes are called transgenic animals. The foreign genes inserted into the genome of the animal using recombinant DNA technology are called transgenes.

Organic acids are among the most versatile ingredients in food and beverage industries. Citric acid, acetic acid, lactic acid, tartaric acid, malic acid, gluconic acid, propionic acid and fumaric acid are some of the organic acids used widely in various industries. They are obtained as the end-products or sometimes as the intermediate components of a particular biochemical cycle. Generally, organic acids are produced commercially either by chemical synthesis or fermentation. However, fermentation processes are the most commonly used method.

Purines are heterocyclic aromatic organic compounds. In the purine ring structure (a fused pyrimidine and imidazole ring), the nitrogen atoms are located at positions 1, 3, 7, and 9.

A reporter gene is used in transgenics to identify whether the transgene has been successfully introduced and expressed in the target tissue, often by producing a visible product like fluorescence.

The introduction of a transgene typically results in the production of a new protein (the product of the transgene) and can alter a biosynthetic pathway by introducing a new enzymatic step or modifying existing ones.

Statement (a) is incorrect because Rosie was a cow, not a buffalo. Statement (b) is incorrect because restriction enzymes are used to cut DNA, not for the isolation of DNA from other macromolecules (which is done via chemical extraction).

In insertional inactivation, if the foreign DNA is inserted into the beta-galactosidase gene, the gene is disrupted and cannot produce the enzyme. Therefore, colonies containing the recombinant plasmid remain white (do not turn blue).

Downstream processing involves the recovery, purification, and packaging of the product after fermentation. Expression is the process that occurs during the upstream phase (fermentation/cultivation).

Biotechnology involves the exploitation of biological processes for industrial and other purposes, especially the genetic manipulation of microorganisms for the production of antibiotics, hormones, vaccines etc. It also involves various other methods involving production, amplification of DNA segments like DNA probe. 

Both wine and beer are essentially the products of the fermentation process - the fermented broth serves as the basis of the product. Other alcoholic beverages (whisky, rum, brandy) fall under the category of distilled spirits. Distillation is the process by which the alcohol is removed from the fermented broth (or wort) by heating the wort until the alcohol vaporizes, after which it is condensed. When almost pure alcohol is distilled from fermentation, the product is called as grain neutral spirits (GNS). 

Southern blotting involves DNA digestion, Gel electrophoresis, Blotting, Probe labeling, Hybridization and washing, and detection.