Question

Which of the following is evidence that a pathogenicity island was initially acquired by horizontal transfer?

a. it contains genes for core, fundamental biological processes such as transcription.
b. it contains genes for a sex pilus.
c. it is passed on to daughter bacteria during cell division.
d. it has a gc percentage different from the rest of the genome.

Answer 1

A significant difference in GC percentage from the rest of the genome is indicative of horizontal transfer, as foreign DNA acquired through this process may have a distinct GC content reflecting the donor organism.Therefore, the correct answer is option d) it has a gc percentage different from the rest of the genome.

Step-by-step explanation:

Pathogenicity islands (PAIs) are large genomic regions in bacteria that encode virulence factors and are often acquired through horizontal gene transfer.

The GC content of a genome is relatively stable over time, and when a foreign DNA segment, such as a PAI, is acquired from another organism, it may have a different GC content than the host genome. Detecting a significant difference in GC percentage between the pathogenicity island and the host genome is indicative of horizontal transfer.

This difference arises because the acquired DNA reflects the GC content of the donor organism. Options A, B, and C are not specific indicators of horizontal transfer in the context of pathogenicity islands.

Therefore, the correct answer is option d) it has a gc percentage different from the rest of the genome.