رسومات الأحياء للصف الثالث الثانوى أ/ حسن محرم

How does the cell membrane help cells to stick together?
The cell membrane helps cells to stick together through a process called cell adhesion. Cell adhesion is a complex process involving various proteins and molecules that allow cells to interact and adhere to each other.

One of the key molecules involved in cell adhesion is called integrin. Integrins are transmembrane proteins that span the cell membrane, with one end extending outside the cell and the other end extending inside the cell. The outside end of the integrin molecule can bind to other molecules on the surface of neighboring cells, or to molecules in the extracellular matrix (ECM), a network of proteins and fibers that surrounds cells.

Once integrins bind to their target molecules, they trigger a signaling pathway that leads to the formation of specialized structures called focal adhesions. Focal adhesions are clusters of proteins that connect the integrins to the cytoskeleton, a network of protein fibers that gives cells their shape and helps them to move.

In addition to integrins, there are other types of adhesion molecules that play a role in cell adhesion, including cadherins and selectins. Cadherins are calcium-dependent proteins that mediate adhesion between cells of the same type, while selectins are carbohydrate-binding proteins that mediate the adhesion of white blood cells to the walls of blood vessels.

Overall, the cell membrane plays a crucial role in cell adhesion by providing a surface for adhesion molecules to interact with each other and the extracellular environment. This allows cells to sticktogether and form tissues and organs, which is essential for the proper functioning of the body.