Question

A fertilized egg divides into daughter cells until it becomes a compact ball. when the ball is a certain size, groups of cells begin to differentiate. the differentiation occurs primarily because

Answer 1

Cell differentiation in an embryo is directed by transcription factors that regulate gene expression, causing cells to specialize into various types that form tissues and organs.

Step-by-step explanation:

The differentiation of cells in a developing embryo occurs primarily because each cell type only "reads" the portions of DNA that are relevant to its own function. After a fertilized egg, or zygote, undergoes several rounds of mitotic division through a process called cleavage, it forms a morula and then a blastocyst. The blastocyst is a structure where cells begin to differentiate. Differentiation is directed by various transcription factors that bind to DNA and regulate gene expression, leading cells to develop into specialized types as the embryo matures. From this ball of undifferentiated cells, tissues and organs begin to form, each with their distinct function.