Statement I: In a continuous culture system, the used medium is drained out from one side while fresh medium is added from the other.
Statement II: In a continuous culture system, the cells are maintained in their stationary phase, which produces a larger biomass and higher yields of the desired protein.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Only statement I is correct.
A recombinant protein is made by host cells that carry the cloned gene. For large amounts, the cells must keep growing at their best. In a continuous culture system, the medium is kept fresh all the time so the cells do not run out of food or collect waste.
Statement I: In a continuous culture system, the used medium is drained out from one side while fresh medium is added from the other. — True. This is how a continuous culture works: used medium goes out on one side and fresh medium comes in on the other.
Statement II: In a continuous culture system, the cells are maintained in their stationary phase, which produces a larger biomass and higher yields of the desired protein. — False. The cells are kept in their log/exponential phase, the phase in which they are physiologically most active. That is why the method gives a larger biomass and higher yields. In the stationary phase growth has stopped, so it would not give these results.
NCERT Extract:
Obtaining the Foreign Gene Product – “… The cells harbouring cloned genes of interest may be grown on a small scale in the laboratory. The cultures may be used for extracting the desired protein and then purifying it by using different separation techniques. 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 desired protein.”