Respuesta :
Every cell in the body gets the same dna, but the cells of an embryo make different structures and take on different roles because different transcription factors are active in different cells. The human body has many transcription factors. Also the body of a bird, a tree or a mushroom! Transcription factors help ensure that the correct genes are expressed in the correct cells of the body and at the right time.
Every cell in the human body shares a common starting point: a fertilized egg. As a result, all of our cells theoretically contain the same DNA — ignoring specific cell types, such as erythrocytes and gametes, and the cumulative effects of DNA changes through mutation and telomere shortening. Despite this, each cell is unique, with one cell type completely dissimilar to another, not to mention being totally different to the original fertilized egg. Why?
The reason is that each cell — whether a neuron, skin cell, or a photoreceptor cell — uses the genes that it has differently. All cells have the same set of genes (~20,000 in humans) but it is up to the individual cell whether each gene is turned on or off.