Final answer:
Cellular identity is communicated by membrane proteins known as markers, which exhibit unique carbohydrate chains. Other membrane proteins include channels like aquaporins, receptors, and pumps that are vital for cellular transport and communication.
Step-by-step explanation:
The type of membrane protein that gives cells specific identity are called markers. These proteins are crucial for cell recognition, and they play a role in various cellular processes such as immune response and cellular signaling. Markers are often composed of carbohydrate chains attached to proteins on the cell's exterior, acting as a unique cellular 'ID card' that distinguishes each cell type.
Membrane proteins serve varied functions, such as channels, receptors, and pumps. Channel proteins, including aquaporins, allow substances to pass through the membrane rapidly. Receptors are involved in signaling, and pumps help in the active transport of substances against the concentration gradient.
In summary, while markers identify the cell, other membrane proteins facilitate the movement of ions and molecules across the cell membrane, each serving a specialized function critical for cell survival and communication.