Final answer:
The plasma membrane of an epithelial cell contains integral proteins involved in transporting molecules across the membrane, while an erythrocyte lacks these specific transport functions. The differences in integral proteins relate to the activities and functions of the cells.
Step-by-step explanation:
The plasma membrane of an epithelial cell and an erythrocyte (red blood cell) have different functions and therefore contain different types of integral proteins. In the plasma membrane of an epithelial cell, you would expect to find integral proteins that are involved in transporting molecules across the membrane, such as carrier proteins and channel proteins. These proteins allow the epithelial cell to selectively absorb or secrete substances. On the other hand, an erythrocyte lacks these specific transport functions, so you would expect the absence of such integral proteins in its plasma membrane.
For example, in the plasma membrane of an epithelial cell lining the small intestine, you would find carrier proteins that facilitate the absorption of nutrients, such as glucose, into the cell. These carrier proteins bind to glucose on one side of the membrane and release it on the other side. In contrast, an erythrocyte primarily functions to transport oxygen and carbon dioxide and does not have the need for such transport proteins in its membrane.
Therefore, the differences in integral proteins between the plasma membrane of an epithelial cell and an erythrocyte are related to the specific activities and functions of these cells.