Final answer:
Differentiation of cells beyond the 8-cell stage is driven by exposure to different environmental signals, which leads to specific gene expression patterns that determine a cell's function. The transcription factor proteins play a critical role in regulating which genes are expressed, allowing cells to specialize into various cell types.
Step-by-step explanation:
The differentiation of cells beyond the 8-cell stage of development is mostly due to exposure of the cells to different environments. Differentiation is a crucial biological process where cells become more specialized in their size, shape, metabolic activity, and overall function as the embryo develops. This process is regulated by the embryonic environment and involves turning on specific genes and turning off others. Cells in different locations get exposed to various chemical signals which lead to the expression of location-specific sets of genes, thus dictating their unique functions within the organism.
Organs develop from the germ layers through differentiation, during which embryonic stem cells express specific gene sets. For instance, cells in the ectoderm will express genes for skin cell characteristics, leading them to differentiate into epidermal cells. The significant factor in gene expression is the transcription factor proteins that bind to DNA and promote or inhibit the transcription of genes. This allows each cell type to only 'read' the portions of DNA relevant to its function, similar to how actors in a movie read only their part of the script.