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The Structure and Function of Plasma Membrane

The plasma membrane is the outermost envelope-like membrane or structure that surrounds the cell and its organelles. It is a double-membrane organelle that is found in both prokaryotic and eukaryotic cells. It is also called the phospholipid bilayer. Lets learn more about the structure and function of plasma membrane.

Plasma Membrane Definition

The plasma membrane is the outermost envelope-like membrane or structure that surrounds the cell and its organelles. It is a double-membrane organelle that is found in both prokaryotic and eukaryotic cells. It is also called the phospholipid bilayer. In all living cells, the plasma membrane is the boundary and is selectively permeable, so only certain substances can get in and out. In addition to this, the plasma membrane bridges the gap between the cell and its surroundings.

Structure of Plasma Membrane

A plasma membrane is about 5 to 8 nm thick and is mostly made up of carbohydrates, phospholipids, proteins, and molecules that are linked together. The plasma membrane is a bilayer of lipids that surrounds and contains the cell’s cytoplasm. Based on their arrangement of molecules and the presence of certain specialized components, it is also described as the fluid mosaic model.

The fluid mosaic hypothesis was initially developed by American biologists Garth L. Nicolson and Seymour Jonathan Singer in 1972. The fluid mosaic model depicts in detail the structure of the plasma membrane in eukaryotic cells, as well as the arrangement of its constituents phospholipids, proteins, carbohydrates, and cholesterol. These components give the plasma membrane a fluid look.

The Structure and Function of Plasma Membrane

Figure 1: The structure and function of plasma membrane

Functions of Plasma Membrane

The Membrane-Embedded Proteins conduct specialised roles such as cell-cell identification and the selective transport of molecules. It provides the cell with safety and a constant environment within the cell. It is accountable for completing several responsibilities. As it supports the movement of white and red blood cells through the blood capillaries, it is flexible in the case of white and red blood cells. 

In addition, it also holds the cytoskeletal structure that provides shape to a cell and associates with the extracellular matrix and other cells to form a tissue. In addition to assisting the Proteins in monitoring and maintaining the chemical environment within the cell, the Membrane facilitates the movement of molecules within the Membrane.

The Fluid Mosaic Model

When asked to describe how the Plasma Membrane is put together, the fluid mosaic model is usually used. Garth L. Nicolson and S.J. Singer came up with the idea first. This model is the best way to explain how the Plasma Membrane is put together. The model shows the structure of the Plasma Membrane as a mosaic of different parts, such as proteins, cholesterol, phospholipids, and carbohydrates. It also shows that the Membrane is fluid. It is between 5nm and 10nm thick. From cell to cell, the carbohydrates, lipids, and proteins that make up the Plasma Membrane are different. For instance, the inner membrane of mitochondria is 24% lipid and 76% protein, while the inner membrane of myelin is 76% lipid and 18% protein.

Facts about Plasma Membrane

Because of the similarities between the words, cell membrane and plasma membrane are sometimes mixed up with one another. However, their structures, compositions, and functions are extremely different from one another, despite the fact that both of these are considered to be protective organelles of the cell. The cell membrane is a type of plasma membrane and is not always the outermost layer of the cell.

FAQ

FAQs on the structure and function of plasma membrane

The plasma membrane is the membrane that separates the inside of the cell from the outside world. It is also called the cell membrane.

Identification, communication, regulation of solute exchange through the membrane, and isolation of the cytoplasm from the outside world are the four primary functions of the plasma membrane.

Most plasma membranes are made up of about 50% lipids and 50% proteins by weight. The carbohydrate parts of glycolipids and glycoproteins make up about 5% to 10% of the mass of the membrane.

 

The fluid mosaic model says that the cell membrane is like a tapestry made up of molecules that are constantly moving. These molecules include phospholipids, cholesterols, and proteins.

Plasma membrane, also known as the cell membrane, is the membrane found in all cells that divides the cell’s interior from its exterior environment. In bacterial and plant cells, a cell wall is attached to the plasma membrane on its outside.