Within the human body, different cells have different characteristics or phenotypes. For example, neurons look and behave very differently from hepatocytes (liver cells). How can this be explained considering that all cells within a person were derived from the same starting cell?

different proteins

Explanation:

All the cells of the body are derived from same cell still different cells have different characteristics or phenotypes. For example, the hemoglobin is present in RBCs only not in any other cell. This is because of a process called gene expression.

This process regulates expression or repression of different set of genes. This makes embryonic cells to become specialized cells that is to perform a specific function. The gene contains DNA which gets transcribed to RNA and then to proteins. The different proteins provides different specificity to cell.