Question

The term "competent" refers to

• A. increasing the competition between cells
• B. making cells impermeable for $DNA$
• C. increasing the efficiency with which $DNA$ enters the bacterium through pores in its cell wall
• D. making cells permeable for divalent cations

Answer 1

Answer: (C)

increasing the efficiency with which $DNA$ enters the bacterium through pores in its cell wall

Answer 2

Transformation is a process by which a cell takes up naked $DNA$ fragment from the environment, incorporates it into its own chromosomal $DNA$ and finally expresses the trait controlled by the incoming $DNA$. Since $DNA$ is a hydrophilic molecule, it can not pass through membranes, so the bacterial cells must be made competent to take up $DNA$. This is done by treating them with a specific concentration of a divalent cation, such as calcium $(Ca{^2+})$ which increases the efficiency with which $DNA$ enters the bacterium through pores in its cell wall.