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Modern Genetic Analysis
16. The Genetic Basis of Development
Key Concepts
A. programmed set of instructions in the genome of a higher organism establishes the developmental fates of cells with respect to the major features of the basic body plan.
Developmental pathways are formed by the sequential implementation of various regulatory steps.
The zygote is totipotent, giving rise to every adult cell type; as development proceeds, successive decisions restrict each cell lineage to its particular fate.
Gradients of maternally derived regulatory proteins establish polarity along the major body axes of the egg; these proteins control the local transcriptional activation of genes encoding master regulatory proteins in the zygote.
Many proteins that act as master regulators of early development are transcription factors; others are components of pathways that mediate signaling between cells.
Some fate decisions are made autonomously by individual cells; many fate decisions require communication and collaboration between cells.
The same basic set of genes identified inDrosophilaand the regulatory proteins that they encode are conserved in mammals and appear to govern major developmental events in manyperhaps allhigher animals.

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