Introduction
In general, a cell membrane is a barrier on the most exterior surface; the cell membrane function separates the elements outside the cell from the elements in the cytoplasm. It is thin and fragile as well as it can be of a minimum of 10 mm in thickness. However, the thickness also depends on the cell type and its chemical structure makes it flexible. The cell membrane functions as the controller of substances inside and outside the cell and its organelles. Furthermore, the cell membranes are also part of various cellular processes like adhesion of the cells, cell signalling, the conductivity of ions etc. Animal cells do not have a cell wall. Animal cell has a cell membrane while plant cells have a strong cell wall which is made of cellulose as well as a cell membrane.
Cell membrane
During cell division, the cell membrane plays an essential role in cytokinesis. Certain species use cilia to change their membranes for eating and movement.
Some cell membrane functions
The primary cell membrane functions include:
- Provide definite shape to the cell
- Protects various cell organelles
- Differential permeability or selective permeability
- Maintaining the integrity of cells inside
- Providing support and preserving the cell’s form
- By balancing endocytosis and exocytosis, it aids in cell growth regulation
- The cell membrane also influences cell signalling and communication
Cell Membrane Structure
Proteins and lipids make up the majority of the cell membrane structure. Lipids can make up anywhere from 20% to 80% of a membrane, depending on its location and function in the body, with proteins accounting for the rest. Proteins monitor and regulate the cell’s chemical environment and assist in the movement of molecules across the membrane while lipids help to give membranes their flexibility.
Components of Cell Membrane
Proteins
These are not abundant like lipids and are an essential part of the cell membrane. In most cells, two types of proteins are present, called peripheral and integral proteins. The integral membranes are integrated into the cell membrane.
Carbohydrates
These are present on the extracellular part of the cell membrane, unlike the proteins. These are generally present at the surface of the cell membrane, just like the peripheral proteins. Carbohydrates with 2-60 monosaccharides might get linked with these proteins – leading to the formation of glycolipids or glycoproteins.
Water and Ions
Water is an essential substance for all the molecules that have life in nature. However, it is not present in the cell membrane as it is integrated into the polar ends, also known as the hydrophilic ends. The ions are also connected with the membranes in multiple ways.
Lipids
Phospholipids make up a significant portion of cell membranes. Phospholipids create a lipid bilayer with their hydrophilic (water-loving) head areas facing the aqueous cytosol and extracellular fluid. The hydrophobic (water-repelling) tail areas face away from the cytosol and extracellular fluid. Only specific compounds can diffuse through the membrane because of the lipid bilayer.
Cholesterol is a lipid that is found in animal cell membranes. Cholesterol molecules are distributed between membrane phospholipids preferentially. Preventing phospholipids from being too closely packed together helps protect cell membranes from becoming stiff. Cholesterol is not found in plant cell membranes.
Factor which affect cell membrane
Temperature
Like the other molecules such as gas and liquids, when the temperature increases, it affects the phospholipids, becoming more flexible with growth. And when the temperature gets down, the phospholipids come closer and make the structure stiffer.
Cholesterol
Inside the cell membrane, the molecules of the cholesterol are scattered to bring the phospholipids together. If these molecules decrease or increase, they affect the structural integrity of the membrane.
Fatty acids
The cell membrane comprises saturated as well as unsaturated fatty acids. They are shown to be straight chains and pack the atoms tightly.
Cell Wall
Plant cells have a cell wall that protects them from the elements. It exists outside the cell membrane and has a tough, flexible and occasionally hard texture. It is mostly cellulose, long carbohydrate fibres such as hemicellulose, lignin and pectin.
The cell wall’s principal roles are:
- Defending the cell from physical harm and pathogen invasion
- Regulates and controls cell growth direction
- Providing the cell with strength, structural support, and the ability to keep its shape
- Acts as a storage unit, storing carbohydrates for plant growth, particularly seed growth
- It allows smaller molecules to pass through it effortlessly
Conclusion:
During cell division, the cell membrane plays an essential role in cytokinesis. Certain species use cilia to change their membranes for eating and movement.
The cell membrane or the plasma membrane conserves the required environment of the cell that allows the right procedure and packaging in a cell. A cell’s required environment is water-based in the interior, known as cytoplasm. This liquid environment is filled with cellular machinery as well as structural elements. Moreover, the cell membrane is the boundary between the cell and its exterior environment. It also controls what is going out of the cell and what is coming into it. Furthermore, the phospholipid bilayer is the structure of the membrane