Development in Drosophila melanogaster is orchestrated by a hierarchy of gene categories that regulate the patterning of the embryo from its earliest stages. Understanding the classification of these genes and their functional roles is essential to decode the genetic basis of development. This article explores the major gene categories involved and matches them with representative gene examples.

Major Gene Categories in Drosophila Development

1. Maternal Effect Genes: These are expressed in the mother and their products are deposited into the egg to establish the initial embryonic polarity. They set up morphogen gradients critical for anterior-posterior and dorsal-ventral axis formation.

2. Gap Genes: Expressed zygotically in broad embryonic regions, these genes define the major subdivisions along the anterior-posterior axis.

3. Pair-Rule Genes: These genes subdivide the embryo into alternating segments, providing a periodic pattern that prefigures the body segmentation.

4. Segment Polarity Genes: Acting later in development, these genes refine segment boundaries and specify anterior-posterior polarity within each segment.

Representative Genes

• Maternal Effect Genes include bicoid, nanos, and torso.

• Gap Genes include hunchback, krüppel, and knirps.

• Pair-Rule Genes include even-skipped, fushi tarazu.

• Segment Polarity Genes include engrailed, wingless.

Correct Matching of Categories and Gene Names

Based on the functional hierarchy and gene examples:

• Category I (Maternal genes) matches Gene A (e.g., bicoid)

• Category II (Gap genes) matches Gene B (e.g., hunchback)

• Category III (Pair-rule genes) matches Gene C (e.g., even-skipped)

• Category IV (Segment polarity genes) matches Gene D (e.g., engrailed)

Among the options provided, the correct matching is:

(1) I – A, II – B, III – C, IV – D

Conclusion

The systematic classification and matching of gene categories with specific gene examples reflect the modular and hierarchical nature of genetic control in Drosophila embryogenesis. This framework has paved the way for advances in developmental biology, illustrating the stepwise refinement of embryonic patterning from maternal inputs to precise segmental organization.