Structure of a Cell Membrane

Structure of a Cell Membrane
Structure of a Cell Membrane (Image: A replica of a cell structure. Ethan hein/ --)

Cells in the human body draw on materials from their environments to sustain cellular functions. The structure of a cell membrane plays an essential role in maintaining a cell's health. This membrane is made up of materials that allow oxygen and nutrients to travel into the cell and waste materials to travel out.


The structure of a cell membrane is designed to keep the internal contents of the cell intact, as well as keep unneeded materials out. The membrane is made up of a number of holes through which chemical processes and material exchanges take place. Embedded inside the membrane are a serious of protein molecules that assist with maintaining the structure of the membrane, as well as coordinating chemical exchanges between the cell and its environment.


The structure of a cell membrane is made up of proteins and phospholipids. Phospholipids are organic compounds made out of fats, or oils. These materials make up the majority of the membrane's surface. Proteins reside within the crevices built into the membrane. Proteins regulate which molecules move in and out of the cell. The Fluid Mosaic Model is a theory that depicts the protein-phospholipid arrangement as designed to act as a fluid material that's made up of a mosaic of components that enhance the membrane's function.


Cell membranes have a bilayer structure through which protein materials cross from one layer to another. Some protein molecules only pass partway through the membrane while others pass all the way through. Two types of proteins are contained within the structure of a cell membrane. Integral proteins are embedded inside the membrane structure. Some integrals serve as pathways for ions and molecules to gain entry to the cell. Peripheral proteins sit on the inner and outer surfaces of the membrane, or may be attached to the ends of an integral protein material. Peripherals play a part in cell signaling processes, and help to maintain the chemical balance inside the cell.

Active Transport

The structure of the cell membrane enables protein molecules to push materials into the cell's interior. When energy is needed to accomplish this, active transport is the mechanism through which protein molecules coordinate this process. As the integral proteins pass all the way through the membrane, they are the ones that provide the pathway, and coordinate these chemical processes. Each type of protein molecule is designed to transport a specific mineral or nutrient into the cell. Active transport mechanisms also provide the pressure needed to move ions into the ion-concentrated cells found in the brain.

Passive Transport

Passive transport activities in cell membrane structures require no energy output as molecules are able to move freely across the membrane. Certain protein molecules might serve as channels that provide access into the cell. Some chemical molecules, such as oxygen, are small enough to pass through the membrane's porous structure on their own. In a process called facilitated diffusion, certain protein molecules act as helpers that guide certain nutrient molecules, such as glucose, through the membrane. Osmosis is another passive transport mechanism that allows ions to pass through cell the membrane. This process happens naturally according to the ion concentrations present both outside and inside the cell.

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