Question

Which of these processes is the means by which a bacterium can directly uptake and incorporate foreign DNA from the environment into its genome?

Options

A
Transduction
B
Transformation
C
Binary Fission
D
Conjugation

Explanation

Transformation is the correct answer because it involves a bacterium directly taking up free DNA from its environment and incorporating it into its own genome, which matches the process described in the question. Transduction is incorrect because it involves DNA transfer via a virus, not direct uptake from the environment. Binary fission is a method of reproduction, not DNA uptake. Conjugation is incorrect as it involves direct contact between bacterial cells to transfer DNA, not environmental uptake.

Transduction

Definition: The process by which bacterial DNA is transferred from one bacterium to another via a virus (bacteriophage).
Example: A bacteriophage infects a bacterium, picks up some of its DNA, and then transfers that DNA to another bacterium during infection.
Key idea: Virus-mediated gene transfer.

Transformation

Definition: The process where a bacterium takes up free (naked) DNA fragments from its environment and incorporates them into its own genome.
Example: Some bacteria can pick up antibiotic resistance genes from dead bacterial cells.
Key idea: Uptake of DNA from surroundings.

Binary Fission

Definition: A form of asexual reproduction in bacteria where a single cell divides into two identical daughter cells.
Example: Most bacteria reproduce this way — E. coli divides every ~20 minutes under ideal conditions.
Key idea: Simple cell division for reproduction.

Conjugation

Definition: The process where DNA is transferred between bacteria through direct contact, usually via a pilus (bridge-like structure).
Example: Transfer of plasmids (e.g., carrying antibiotic resistance genes) from one bacterium to another.
Key idea: Direct cell-to-cell DNA transfer.