CELL
BIOLOGY
Cell The Unit of Life
,Learning Objectives
01 Understand the fundamental differences between prokaryotic and eukaryotic cell organization
02 Study the structure and functions of cell organelles as per NCERT Class 11
03 Analyze the fluid mosaic model and membrane transport mechanisms
04 Compare and contrast mitosis and meiosis with significance
05 Explain the cell cycle with regulatory checkpoints
06 Apply concepts to NCERT-level analytical questions
2
,What is a Cell?
DEFINITION
The cell is the basic structural and functional unit of all
living organisms. The word 'cell' was coined by Robert
Hooke (1665) while observing cork under a microscope.
Nucleus
Mito.
Nucleolus ER
CELL THEORY (Schleiden & Schwann)
• All living organisms are composed of cells and cell
products Cytoplasm
• The cell is the basic unit of structure and function
• All cells arise from pre-existing cells (Rudolf Virchow —
Omnis cellula-e-cellula) Cell Membrane
3
, Prokaryotic Cell Structure
KEY FEATURES ()
• No well-defined nucleus; genetic material is a
naked circular DNA (nucleoid)
• Lack membrane-bound organelles
Nucleoid
(Circular DNA) Flagellum • Cell wall composed of peptidoglycan (in bacteria)
• Ribosomes are 70S type (50S + 30S subunits)
• May have plasmids — small extra-chromosomal
DNA
• Mesosomes: infoldings of plasma membrane for
70S Ribosomes respiration
• Size: typically 0.1–5 µm
Cell Membrane
• Examples: Bacteria (E. coli, Mycoplasma),
Cell Wall Cyanobacteria (blue-green algae)
4
BIOLOGY
Cell The Unit of Life
,Learning Objectives
01 Understand the fundamental differences between prokaryotic and eukaryotic cell organization
02 Study the structure and functions of cell organelles as per NCERT Class 11
03 Analyze the fluid mosaic model and membrane transport mechanisms
04 Compare and contrast mitosis and meiosis with significance
05 Explain the cell cycle with regulatory checkpoints
06 Apply concepts to NCERT-level analytical questions
2
,What is a Cell?
DEFINITION
The cell is the basic structural and functional unit of all
living organisms. The word 'cell' was coined by Robert
Hooke (1665) while observing cork under a microscope.
Nucleus
Mito.
Nucleolus ER
CELL THEORY (Schleiden & Schwann)
• All living organisms are composed of cells and cell
products Cytoplasm
• The cell is the basic unit of structure and function
• All cells arise from pre-existing cells (Rudolf Virchow —
Omnis cellula-e-cellula) Cell Membrane
3
, Prokaryotic Cell Structure
KEY FEATURES ()
• No well-defined nucleus; genetic material is a
naked circular DNA (nucleoid)
• Lack membrane-bound organelles
Nucleoid
(Circular DNA) Flagellum • Cell wall composed of peptidoglycan (in bacteria)
• Ribosomes are 70S type (50S + 30S subunits)
• May have plasmids — small extra-chromosomal
DNA
• Mesosomes: infoldings of plasma membrane for
70S Ribosomes respiration
• Size: typically 0.1–5 µm
Cell Membrane
• Examples: Bacteria (E. coli, Mycoplasma),
Cell Wall Cyanobacteria (blue-green algae)
4
