Class 9 - Biology - Cell: Fundamental Unit Of Life - Cell Membrane - Structure and Functions (#cbsenotes)(#eduvictors)

Cell Membrane - Structure and Functions

Class 9 - Biology - Cell: Fundamental Unit Of Life

Plasma Membrane Diagram
Image Credits: Ruth Lawson. Otago Polytechnic Wikimedia

Structure:

1. Cell membrane is also called as plasma membrane or plasma lemma.
    
2. It is the limiting boundary of each cell which separates the cytoplasm from its surroundings.
   
3. It is found in both plant as well as animal cells.
   
4. It is the outermost covering of a cell in case of animals and lies below the cell wall in case of plants.
    
5. It is made up of proteins and lipids where proteins are sandwiched between bilayer of lipids.
   
6. Plasma membrane is selectively permeable in nature. It allows or permits the entry and exit of some materials in and out of the cell.
   
7. Singer and Nicholson gave the fluid mosaic model of plasma membrane. According to them, it consists of a protein layer sandwiched between two layers of lipids.
   
8. It is in quasifluid state. It is 75A thick.
   
9. It is flexible and can be folded, broken and reunited.
   
10. It is the living component of the cell.

Credits: Mariana Ruiz (edited by AlokPrasad) Wikimedia

Functions:

1. It selectively regulates the entry and exit of substances into and out of the cell. That's why it is called selectively permeable or semi-permeable.
   
2. It provides an outer boundary to the cell and protects cell from injury.
   
3. Provide organic connections among adjacent cells.
   
4. Maintains distinct composition of the cell.

☛See also:

Ch 5 - Fundamental Unit of Life (Q & A)
Ch5 - Fundamental Unit of Life (MCQs)
Ch5 - Fundamental Unit Of Life (Question Bank)
Ch5 - Fundamental Unit Of Life - Quiz On Cell Organelles
Ch 5 - Interactive Cell - Play to learn about cell organelles
Ch5 - Fundamental Unit of Life (Worksheet)
Ch5 - 7 Points About Plasmolysis
Ch5 - Cell - Very Short Answer Based Questions (Set-1)