Plasma Membrane vs. Cell Wall
Changes With Time
Plasma Membrane vs. Cell Wall
The cell is a structural and functional unit of life. It is made up of many organelles which have their specific structure and function. Plasma membrane and cell wall are two important membranous structures of a cell that play many important roles. They provide shape, protection, and rigidity, etc. to the cell. They act as cytoplasmic bridges which help in intercellular communication and transfer etc. Although they both are membranous structures and have many similar functions, there is a large number of differences that exist between them. The plasma membrane is also called a cell membrane while there is no other name for the cell wall. The plasma membrane is present in almost every type of cell while the cell wall is present in just plant cells, bacteria, fungi, and algae. The plasma membrane is a living and inner cover of the cell while the cell wall is an outer most and nonliving cover of the cell.
What is Plasma Membrane?
Plasma Membrane is also called as Plasma Lemma or Cell Membrane. It is a membranous structure that is present in almost every type of cell. It is the inner covering that covers the cytoplasm of the cell and is semi-permeable in nature which means that it is able to transfer some items from it and stops the movement of others. So, it is playing its role in homeostasis because it maintains the internal environment of the cell to a constant level. The plasma membrane is a thin structure 5-10nm wide and mostly made up of phospholipids, cholesterol, carbohydrates and proteins. It also has receptors that help in intercellular communication. The plasma membrane is a living membrane and needs proper nutrition. It shrinks during drought conditions.
- It plays many important functions in the cell, i.e.
- It provides protection to the protoplasm.
- It helps in intercellular communication.
- It allows the passage of some specific material through it so, maintains the internal environment of the cell and protects it from harmful material.
- In some cells, the cell membrane has different types of projections like flagella and pili, etc. that help in movement and reproduction respectively.
What is Cell Wall?
The cell wall is the outermost covering of the cell that is present in Plant, fungi, bacteria, and algae. It is not present in each type of cell. It covers the plasma membrane and is fully permeable in nature. So, it allows the movement of small size molecules and stops the entry of large size material. A cell wall is a thick membrane 4-20um wide and its thickness keeps on increasing with time due to deposition of more material. It is made up of chitin in fungi, cellulose in plants and peptidoglycan in bacteria. So, its composition varies from organism to organism. It is nonliving in Nature and does not need any nutrition.
- It provides protection to the cell from the harsh external environment.
- It maintains osmotic pressure in the cell.
- It provides shape and rigidity to the cell.
- It stops the entry of large size material into the cell.
- It also prevents the cell from being toxic.