Cell The Unit of Life Notes, Cell Biology NCERT Notes, Class 11 Biology Cell Notes, NEET Cell Chapter Notes, Cell Organelles Notes, Cell The Unit of Life PYQ, NEET Biology 2026, NCERT Line by Line Biology.
The cell is the fundamental structural and functional unit of life. All living organisms are made up of cells. 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
Theodor Schwann
Modified by:
Rudolf Virchow
Main Points
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
Features
No true nucleus
No membrane-bound organelles
Circular DNA
Small size
Eukaryotic Cells
Examples:
Plants
Animals
Fungi
Protists
Features
True nucleus present
Membrane-bound organelles present
Linear chromosomes
Cell Shape
Cell shape depends upon function.
Examples:
Cell
Shape
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
Garth Nicolson
Cell Wall
Present in plant cells.
Composition
Cellulose
Hemicellulose
Pectin
Functions
Protection
Mechanical support
Middle Lamella
Made of calcium pectate.
Osmosis
Movement of water through a semipermeable membrane from higher water potential to lower water potential.
Important Terms
Hypotonic
Hypertonic
Isotonic
NCERT Point
Plant cells become turgid in hypotonic solution.
Cytoplasm
Semi-fluid matrix between nucleus and plasma membrane.
Contains:
Organelles
Cytosol
Inclusions
Endoplasmic Reticulum (ER)
Rough ER
Ribosomes present
Protein synthesis
Smooth ER
Lipid synthesis
Detoxification
Golgi Apparatus
Discovered by:
Camillo Golgi
Functions
Packaging
Secretion
Formation of lysosomes
Lysosomes
Known as:
"Suicidal Bags"
Contain hydrolytic enzymes.
Function
Intracellular digestion.
Mitochondria
Powerhouse of Cell
Structure
Outer membrane
Inner membrane
Cristae
Matrix
Functions
ATP production
Cellular respiration
NCERT Point
Mitochondria possess their own DNA and ribosomes.
Plastids
Present only in plant cells.
Types
Chloroplast
Photosynthesis
Chromoplast
Colored pigments
Leucoplast
Storage
Chloroplast Structure
Grana
Thylakoids
Stroma
NCERT Point
Chlorophyll is present in thylakoid membranes.
Ribosomes
Site of Protein Synthesis
Types
70S (Prokaryotes)
80S (Eukaryotes)
Centrosome
Present in animal cells.
Function
Spindle formation during cell division.
Cilia and Flagella
Function
Movement
Example
Cilia → Trachea
Flagella → Sperm
Nucleus
Control center of the cell.
Components
Nuclear membrane
Nucleoplasm
Chromatin
Nucleolus
Chromosomes
Made of:
DNA
Proteins
Human Chromosomes
46 chromosomes
(23 pairs)
Chromatin Types
Euchromatin
Lightly stained
Transcriptionally active
Heterochromatin
Darkly stained
Inactive
Microbodies
Examples:
Peroxisomes
Glyoxysomes
Function
Metabolic activities
Plant Cell vs Animal Cell
Feature
Plant Cell
Animal Cell
Cell Wall
Present
Absent
Chloroplast
Present
Absent
Vacuole
Large
Small
Centrosome
Absent
Present
Most Important NCERT Points
✔ Cell is the structural and functional unit of life.
✔ Fluid mosaic model explains plasma membrane.
✔ Middle lamella contains calcium pectate.
✔ Ribosomes are sites of protein synthesis.
✔ Mitochondria possess DNA and ribosomes.
✔ Chloroplasts contain chlorophyll.
✔ Lysosomes contain hydrolytic enzymes.
✔ Centrosome helps in spindle formation.
NEET PYQ Practice Questions
Q1. Fluid Mosaic Model was proposed by:
A. Watson & Crick
B. Singer & Nicolson
C. Schleiden & Schwann
D. Virchow
✅ Answer: B
Q2. Powerhouse of the cell is:
A. Golgi Body
B. Ribosome
C. Mitochondria
D. Lysosome
✅ Answer: C
Q3. Site of protein synthesis:
A. Lysosome
B. Ribosome
C. Vacuole
D. Centrosome
✅ Answer: B
Q4. Cell wall middle lamella contains:
A. Cellulose
B. Chitin
C. Calcium Pectate
D. Lignin
✅ Answer: C
Q5. Which organelle possesses its own DNA?
A. Ribosome
B. Golgi Body
C. Lysosome
D. Mitochondria
✅ Answer: D
Last-Minute NEET Revision
Focus on:
Cell Theory
Fluid Mosaic Model
Cell Organelles
Mitochondria
Chloroplast
Ribosomes
Nucleus
Plant vs Animal Cell
NCERT Diagrams
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