Cell: The Unit of Life

Cell Theory

Formulated by Schleiden and Schwann, and later modified by Rudolf Virchow, it states that all living organisms are composed of cells and products of cells, and all cells arise from pre-existing cells.

Prokaryotic vs Eukaryotic Cells

Prokaryotic cells lack a membrane-bound nucleus and distinct organelles (e.g., bacteria), whereas eukaryotic cells possess a true nucleus and complex membrane-bound organelles (e.g., plant and animal cells).

Plasma Membrane Structure

Described by the Fluid Mosaic Model proposed by Singer and Nicolson, the cell membrane is made of a phospholipid bilayer with embedded proteins that provide fluidity and selective permeability.

Endomembrane System

A group of interconnected membranous organelles including the endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles whose functions are coordinated.

Mitochondria and Plastids

Mitochondria are the powerhouse of the cell responsible for ATP production, while plastids (like chloroplasts) are found in plant cells and are involved in photosynthesis.