Question

An alveolar cell in your lung looks and functions completely different from a circulating white blood cell. If you were to compare DNA, RNA and proteins in these cells, which would be the same? Which would be different?

Answer 1

All the cells in human beings are genetically almost identical and thus the genetic material (DNA and RNA) are almost same in all cells. It is the regulation of gene expression which differenciate the cell types with one another. Expression of different genes in different cell types lead to production of different proteins which make the cells functionally different. For example gene for insulin hormone is present in all cells but the expression of this gene occurs only in pancreatic beta cells.

Hence, an alveolar cell and a circulating WBC will have same DNA and RNA but their protein contents will be different.