Indicate whether each of the following descriptions better applies to egg-polarity genes (E), gap genes (G), pair-rule genes (P), or segment-polarity genes (S). Your answer would be a four-letter string composed of letters E, G, P, and S only, e.g. SSGG.
( ) Mutations in these genes show a maternal effect.
( ) Mutations in these genes leave the embryo with only half the number of normal segments.
( ) Mutations in these genes produce a normal number of segments but with part of each segment replaced by a mirror-image duplicate of other parts of the segment.
( ) Mutations in these genes can eliminate one or two groups of adjacent segments altogether.

Question

Indicate whether each of the following descriptions better applies to egg-polarity genes (E), gap genes (G), pair-rule genes (P), or segment-polarity genes (S). Your answer would be a four-letter string composed of letters E, G, P, and S only, e.g. SSGG.
( )	Mutations in these genes show a maternal effect.
( )	Mutations in these genes leave the embryo with only half the number of normal segments.
( )	Mutations in these genes produce a normal number of segments but with part of each segment replaced by a mirror-image duplicate of other parts of the segment.
( )	Mutations in these genes can eliminate one or two groups of adjacent segments altogether.

Quizplus · Accepted Answer

Egg-polarity genes in Drosophila are maternal-effect genes: their mRNA transcript is deposited by the mother into the egg, and hence it is the mother's genome (rather than the zygote's genome) that is critical. Mutations in gap genes result in the elimination of one or more adjacent segments altogether. Mutations in pair-rule genes cause a series of deletions affecting alternate segments, leaving the embryo with only half as many segments as usual. Finally, mutations in segment-polarity genes produce the right number of segments but with a part of each segment replaced by a mirror-image duplicate of another part of the segment.

Indicate Whether Each of the Following Descriptions Better Applies to Egg-Polarity