Cell Biology: Cell Structure, Functions and Significance
Cell Biology: Cell Structure, Functions and Significance – Complete Notes for NEET 2026
The cell is the fundamental structural and functional unit of life. This chapter is highly important for NEET because many questions are directly asked from NCERT diagrams, organelles, and cell theory.
What is a Cell?
A cell is the basic unit of life capable of performing all life processes.
- Examples:
- Amoeba → Single cell
- Human body → Trillions of cells
Cell Theory
Proposed by: Matthias Schleiden and Theodor Schwann
Modified by: Rudolf Virchow
- All organisms are made of cells.
- Cell is the basic unit of life.
- Every cell arises from a pre-existing cell.
NCERT Line: Omnis cellula e cellula (Every cell originates from another cell.)
Types of Cells
Prokaryotic Cells
- Examples: Bacteria, Cyanobacteria
- No true nucleus
- No membrane-bound organelles
- Circular DNA
- Small size
Eukaryotic Cells
- Examples: Plants, Animals, Fungi, Protists
- True nucleus present
- Membrane-bound organelles present
- Linear chromosomes
Cell Shape
Cell shape depends upon function.
- RBC → Biconcave
- Neuron → Long and branched
- Muscle Cell → Elongated
- Amoeba → Irregular
Structure of Cell – Major Components
- Plasma Membrane
- Cytoplasm
- Nucleus
Plasma Membrane
Outer boundary of cell. Functions: Selectively permeable, regulates transport, protection.
Fluid Mosaic Model proposed by S.J. Singer and Garth Nicolson.
Cell Wall
Present in plant cells. Composition: Cellulose, Hemicellulose, Pectin. Functions: Protection, Mechanical support.
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