Illustrate the design of a bioreactor. Highlight the difference between a flask in your laboratory and a bioreactor which allows cells to grow in a continuous culture system.

(N/A) Small volume cultures cannot yield appreciable quantities of products. To produce in large quantities, the development of bioreactors, where large volumes ($100$ - $1000$ litres) of culture can be processed, was required. Thus, bioreactors can be thought of as vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial, plant, animal or human cells. $A$ bioreactor provides the optimal conditions for achieving the desired product by providing optimum growth conditions (temperature, $pH$, substrate, salts, vitamins, oxygen).

Flask	Bioreactor
$(1)$ Flask is used for small laboratory-scale testing of a culture.	$(1)$ Bioreactor is used for commercial-scale production.
$(2)$ The cells harbouring cloned genes of interest may be grown on a small scale in the laboratory.	$(2)$ The cells can also be multiplied in a continuous culture system wherein the used medium is drained out from one side while fresh medium is added from the other to maintain the cells in their physiologically most active log/exponential phase. This type of culturing method produces a larger biomass leading to higher yields of the desired protein.
$(3)$ Small volume cultures cannot yield appreciable quantities of products.	$(3)$ To produce in large quantities, the development of bioreactors, where large volumes ($100$ - $1000$ litres) of culture can be processed, was required.