How Do Specialized Cells Form?

I know that cells come from other cells, but I had trouble understanding how each cell knows what type of cell it is supposed to be. I went to askascientist.org, and I learned that even though DNA is identical in every cell, not every gene that is encoded by DNA is expressed in every cell (Revollo, 2008). All cells have a set of genes that encode proteins necessary for every type of cell. Each cell also has tissue-specific sets of genes that are unique to a particular tissue or organ. For example, bone cells express bone-specific genes. The cells become specialized for a certain function during an organism's development. A totipotent embryonic cell can become any type of specialized cell, and differentiates due to cues from the environment of the nearby cells (Revollo, 2008). These cues, along with when the signals are received, instruct the cells of the embryo to differentiate.

Revollo,J.Y. (2008). How do specialized cells form? Retrieved from http://askascientist.org