Scientists have found that the lifetimes of mRNAs coding for pair- rule regulatory elements in Drosophila embryos may be measured in minutes. What does this suggest about the overall developmental plan of an animal body?
A) Timing of pair- rule sequence determination is not as important as spatial signaling.
B) Each segment specified by pair- rule mRNAs is completely determined in the embryo in a very short time.
C) Building an animal body requires a sequence of steps; each of these steps is precisely timed.
D) mRNAs in general have short lifetimes; this is not a surprising finding.

Question

Quizplus · Accepted Answer

The short lifetimes of mRNAs coding for pair-rule regulatory elements suggests that the developmental plan of an animal body requires a sequence of steps that are precisely timed. This is necessary for the proper initiation and patterning of each segment in a very short period of time. The timing of pair-rule sequence determination and spatial signaling are both important factors in this process. The general finding that mRNAs have short lifetimes is not particularly relevant to the question.

Scientists Have Found That the Lifetimes of MRNAs Coding for Pair-