A bacterial colony grows steadily by rapid cell division in a medium that is rich in the amino acid alanine.If the alanine concentration drops, cell division slows.Supplying more alanine results in resumed cell division.Alanine is thus
A) a fertilization signal.
B) a ter site.
C) a reproductive signal.
D) an oncogene.
E) an ori site.

Question

Quizplus · Accepted Answer

The fact that the bacterial colony grows steadily with rapid cell division when alanine is present suggests that alanine is a signal for reproduction or cell division. When the alanine concentration drops, cell division slows, indicating that the presence of alanine is necessary for continued reproduction. Supplying more alanine results in resumed cell division, further supporting the idea that alanine is a reproductive signal. Therefore, option C is the best choice.

Option A (fertilization signal) is incorrect because fertilization involves the merging of gametes from two individuals, and alanine has not been shown to act as a signaling molecule in this context.

Option B (ter site) and E (ori site) are incorrect because these are specific DNA sequences that play a role in DNA replication and segregation, and they are not related to amino acids.

Option D (oncogene) is incorrect because oncogenes are genes that can cause cancer when mutated or overexpressed, and they are irrelevant to the context of bacterial growth and alanine concentration.

A Bacterial Colony Grows Steadily by Rapid Cell Division in a Medium