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

question 22

Multiple Choice

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.

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