Question

What is the standard initial cell density for the initiation of a suspension culture?

• A. $5 \times 10^2$ cells $ml^{-1}$
• B. $2 \times 10^3$ cells $ml^{-1}$
• C. $5 \times 10^4$ cells $ml^{-1}$
• D. $2 \times 10^2$ cells $ml^{-1}$

Hint:

Remember the "Power of 4". Most successful cell suspensions start around the $10^4$ cells/ml mark.

Answer 1

The Correct Option is C

Concept: A suspension culture consists of cells or cell aggregates dispersed in a moving liquid medium. For these cells to survive and divide, there is a "critical density" required to condition the medium with necessary growth factors.

Step 1: The Importance of Cell Density.
If the initial cell density is too low, the cells cannot sufficiently modify the chemical environment of the medium to support their own growth (the "nursing effect"). If it is too high, nutrients are depleted too quickly.

Step 2: Standard Protocol Values.
In most plant biotechnology protocols, the standard range for initiating a healthy suspension culture is between $10^4$ and $10^5$ cells per milliliter. The value $5 \times 10^4$ cells $ml^{-1$} falls perfectly within this optimal range to ensure rapid entry into the log phase of growth.