Saran's Learn Microbiology

  ULTRASTRUCTURE OF BACTERIA Ultrastructure of Bacteria Cell wal ·        Cell wall acts as a backbone of cell and gives shape and rigidity to the cell. ·        Gram positive bacteria composed of Peptidoglycan (Thick – Multilayered) and Teichoic acid. ·        Gram negative bacteria composed of Peptidoglycan (Thin – Single layered), Periplasmic space, Outer membrane, Lipopolysaccharides, Lipid and Lipoprotein. ·        Peptidoglycan is a sugar backbone with peptide side chains that are cross linked. It is made up of NAM (N – acetyl muramic acid) and NAG (N – acetyl glucosamine). ·      One of the most abundant polypeptide called porin is present and it helps in the diffusion of solutes. ·    Bacterial cell wall confers Osmotic protection from toxic substances and Gram staining characteristics. Plasma Membrane ·        Plasma membrane is also called as Cell membrane or Cytoplasmic membrane. ·        Plasma membrane

  BACTERIA ·        Prokaryotic in nature. ·        Christian Gottfried Ehrenberg introduced the word "bacterium" in 1828. ·        Measured in micrometer (µm) ·        Unicellular in nature. ·        Previously, Thiomargarita namibiensis was considered as Largest bacteria. ü   Gram negative cocci. ü   Alpha Proteobacteria. ü   Chemolithotrophs. ü   Found in the ocean sediments of the coast of Namibia in 1999. ü   Large enough to be visible to the naked eye, attaining a size of 0.1– 0.3 mm or 100 to 300 µm in diameter. ·        Recently, the world's largest bacterium has been discovered amongst the Mangroves of the Caribbean island of Guadeloupe. Measuring over a centimetre long, Thiomargarita magnifica is over 5000 times bigger than the average microbe. ·        Longest bacteria - Epulopiscium fishelsoni ü   Gram Positive Rods. ü   Discovered in the Gut of Surgeon fish. ü   Large enough to be seen with the naked eye at 600 µm. Million time

  CELL ·        Cell is defined as the basic structural, functional and biological unit of all living organisms. ·        The word “Cell” was derived from the Latin word “ Cella ” which means “Small Room”. ·        The cell was first discovered by the English Botanist Robert Hooke in 1665 from his microscope. ·        Cells can replicate independently and called as “Building blocks of life”. ·        The study of cell is “Cell Biology” or “Cytology”. ·        Living organisms can be classified as Unicellular organisms (Contains single cell) (Example - Bacteria, Yeast, Protozoa and Some algae) and Multicellular organisms (Contains multiple cells) (Example - Fungi, Algae, Plants and Animals). CELL THEORY ·        In 1838, German Botanist Matthias Jacob Schleiden discovered the all the plants were composed of cells. ·        In 1839, German Zoologist Theodor Schwann discovered that all the animals were composed of cells. ·        In 1855, German Physician Rudolph Virch