What is the role of homeobox genes in development?

• A. Homeobox genes encode transcription factors that regulate body plan development along the anterior-posterior axis.
• B. They encode ribosomal proteins.
• C. They are non-coding RNAs.
• D. They are proteins that degrade mRNA.

Answer: (A)

Homeobox genes encode transcription factors that regulate body plan development along the anterior-posterior axis. They produce proteins with a homeodomain that binds DNA and controls the expression of many downstream genes, helping to specify the identity of different body segments and organs during development. In many species, these genes are organized in clusters, and their expression patterns along the body axis reflect their position in the cluster, a feature that helps establish the orderly patterning of the organism. When these genes are mutated, segments can take on identities of other segments, illustrating their central role in directing developmental programs. They are coding genes for transcription factors, not ribosomal proteins, non-coding RNAs, or enzymes that degrade mRNA.