Final answer:
A morphogen is a diffusible biochemical molecule that influences cell differentiation and organ formation during development through its concentration gradient, acting as part of the gene expression regulation mechanism.
Step-by-step explanation:
A morphogen is best defined as a diffusible biochemical molecule that can determine the fate of a cell by its concentration. Morphogens are key in the regulation of gene expression during the development of an organism. They function by creating a concentration gradient within a developing tissue, and cells respond differently to various morphogen levels, which guides their differentiation into specific cell types and contributes to the proper formation of organs and tissue structures. This regulatory process is crucial for the organism to develop normal organs and organ systems.
The action of morphogens ties into the overall concept of gene expression, where transcription factors, including homeobox genes and proteins containing homeodomains, bind to DNA to promote or inhibit the transcription of genes. This finely tuned mechanism allows cells to develop into their specialized form and function, leading to the formation of different tissues and organs in an organism.