What is the Plasma Membrane: Understanding Cell Biology

One thing that tends to confuse a fair number of people in the field of biology is understanding what a cells plasma membrane is. Essentially, what it does mark the boundary between the outside and the inside of the cell. Additionally, it helps regulate the passage of materials inside and outside of the cell. It is composed of a phospholipid bilayer that has embedded proteins in. Within this bilayer, polar heads of the phospholipids face into the watery side. However, the nonpolar tales face each other. There are six main types of proteins that all form different purposes: membrane proteins, transport proteins, cell recognition proteins, receptor proteins, enzymatic proteins, and junction proteins.

Membrane proteins are also known as channel proteins. What these proteins do form tunnels that allow certain molecules to either enter or exit the cell. Transport proteins are another type of protein in the plasma membrane. The function of these proteins is to help with the passage of molecules through the membrane, often times requiring the input of energy.

Cell recognition proteins are another unique type of protein in the plasma membrane. What they do is they help the body distinguish between its own cells and the cells of other organisms. Receptor proteins in the plasma membrane allow a signal molecule to bind with the cell, which in turn causes a cellular response.

Enzymatic proteins are the proteins in the plasma membrane that are directly related to meet metabolic reactions. Finally, junction proteins are the type of protein in the plasma membrane that help form junctions between cells. They allow multiple cells to combine together and communicate with one another.

The plasma membrane itself is very very small and can only be seen with a microscope. Cells themselves are very small, but have a large surface area. The purpose of this large surface area is so that they can have a large membrane in which things and materials can enter and exit the cells easily. Without the plasma membrane, these cells would have no way of regulating what materials enter and exit them. The specific proteins are extremely important, as they all have their own duties and serve their own purposes. Because of this, it is essential that any biologist or student understands what each and every protein does. Without understanding how cells are made up, we would not be able to understand how life is formed and regulated by our bodies.

Source:
Benitz, Bill. Lecture: Biology. September 7, 2009