Assertion Statement Analysis
The assertion states that in a synchronous culture, most cells advance to the subsequent cell cycle phase simultaneously. This is the defining characteristic of a synchronous cell culture, where cells are induced to divide at approximately the same time. Therefore, the assertion is true.
Reason Statement Analysis
The reason suggests that synchronous cultures can be achieved by starving cells of essential nutrients. Nutrient deprivation (like serum starvation) is a common technique used to arrest cells at a specific checkpoint (often G1) in the cell cycle. When the nutrient is reintroduced, the arrested cells often re-enter the cycle together, creating synchrony. Therefore, the reason is also true.
Relationship Between Assertion and Reason
While nutrient starvation is a valid method to *obtain* a synchronous culture, it is not the fundamental reason *why* cells in a synchronized state progress through the cell cycle simultaneously. The simultaneous progression is due to the synchronized restart of the cell cycle from the arrest point. The starvation method *enables* this synchronized restart but doesn't explain the inherent mechanism of simultaneous progression once synchronized. Thus, the reason supports the *establishment* of synchrony but is not the direct explanation for the *behavior* described in the assertion.
Conclusion
Both the assertion and the reason are factually correct statements related to cell culture techniques. However, the reason explains a method for achieving synchrony, not the underlying cause for the synchronized cell cycle progression itself. Therefore, the reason is not the correct explanation for the assertion.
Important Questions from Kinetics of Cell Growth
- In the process of generating a clonal mammalian cell line, a single cell was seeded in a well of a cell culture plate. After the first 48 hours, one of the progeny cells underwent apoptosis due to a new mutation. If the doubling time of the cells is 24 hours and no more cell death occurs, the total number of cells after a total of 7 days from seeding will be ______. (answer in integer)
- A synchronous culture containing $1.8 \times 10^5$ monkey kidney cells was seeded into three identical flasks. The doubling time of these cells is 24 h. After 24 h, the cells from all the three flasks were pooled and dispensed equally into each well of three 6-well plates. The number of cells in each well will be ________ $\times 10^4$.
- Maximum specific growth rate ($\mu_{max}$) of a microorganism is calculated by taking the (In=loge, X=biomass, t = time)
- Which one of the following is NOT used for the measurement of cell viability in animal cell culture?
- A T-flask is seeded with $10^5$ anchorage-dependent cells. The available area of the T-flask is $25 \text{ cm}^2$ and the volume of the medium is $25 \text{ ml}$. Assume that the cells are rectangles of size $5 \text{ µm} \times 2 \text{ µm}$. If the cells grow to monolayer confluence after $50 \text{ h}$, the growth rate in number of cells/($\text{cm}^2.\text{h}$) is _________ $ \times 10^5$.
