All in One Knowledge

1. What is a Cell? Cell is the structural and functional unit of life. It distinguishes living from non-living. All life processes occur inside cells. Cells can exist independently. 2. Discovery of Cell Robert Hooke (1665) – Discovered dead cells in cork. Anton van Leeuwenhoek – Discovered living cells. Robert Brown – Discovered nucleus. 3. Cell Theory Proposed by Schleiden and Schwann. Schleiden: All plants are made of cells. Schwann: All animals are made of cells. Modified by Rudolf Virchow: “All cells arise from pre-existing cells.” Final Cell Theory: All living organisms are made of cells. All cells arise from pre-existing cells. 4. Types of Cells (A) Prokaryotic Cells Found in Bacteria, Mycoplasma (PPLO). No nuclear membrane. No membrane-bound organelles. DNA present in nucleoid. Ribosomes: 70S. (B) Eukaryotic Cells Found in Protista, Fungi, Plants, Animals. True nucleus with nuclear membrane. Membrane-bound organelles present. Ribosomes: 80S (cytoplasm), 70S (mitochondria & c...