What Types of Organic Molecules Make Up a Cell Membrane?

By Susan Davis
Microscopic image of cells.
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The membrane of a cell keeps the contents of a cell within a defined space. You can think of it as a kind of zip-lock bag. Add a few small holes to the bag and you would have something very much like a cell membrane. The holes in a cell membrane allow contents to flow in and out of the cell. A cell membrane is made up of three different organic molecules.


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A cell membrane is composed of many parts as opposed to one single component or piece. Think of it like a jigsaw puzzle with all of the pieces fitting tightly togtether. One of the main organic components is protein, the function of which is to help particles move in and out of cells. Protein molecules can be found around the small holes in a cell membrane. The movement of these organic protein molecules is very limited. They are not able to move around the cell but remain by the holes in the membrane, acting as receptors.


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Phospholipids make up the majority of a cell membrane and have the function of containing all the components of a cell. Phospholipids have two ends, one of which is attracted to water, called hydrophilic, so it makes up the outside of the membrane. The other side faces the interior of a cell and is hydrophobic. Phospholipids determine the strength and flexibility of a cell and maintain its shape. Phospholipids can contain cholesterol. The amount of cholesterol helps to determine the strength of a cell membrane.


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Carbohydrates attach to the outer surface of both proteins and phospholipids. These are also known as fatty acids. These organic molecules are made up of both simple and complex sugars. The main function of carbohydrates is to help form a barrier on the cell membrane so that the cell can be protected and so other types of cells can be recognized. An example of a carbohydrate on a cell membrane is antigens on blood cells.


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Every cell, including its membrane, is different, as human fingerprints are. The organic molecules that form a cell membrane are always the same materials, but the cell membranes are all different in their specific makeup and design. These differences control how the body's systems work together to help the organs function and to fight off diseases and illnesses. They also ensure that our bodies can take in medication and develop antigens. The individuality and specialization of each cell is what makes our bodies work.