1. Cell Wall of Acid Fast Bacteria @ Contains an inner peptidoglycan layer and an outer membrane layer. @ The inner peptidoglycan layer is joined to the cell membrane by the Phosphatidyinositol mannosides (PIM) chain @ Also the inner peptidoglycan layer is joined to an arabinogalactan layer (arabinose and galactose) by a lipoarabinomannan chain. @ The arabinogalactan layer is attached directly to the mycolic acids layer.

3. @ The mycolic acids layer is followed by a layer of acyl lipids. @ Porins are found to transport the hydrophilic molecules through the outer membrane layer. @ Proteins are located on the surface of cell @ Mycolic acids are esterified to form polysaccharides (wax D) and glycolipids. @ Lipids are responsible for : * Acid fast staining * Stickiness of mycobacteria

5. Bacterial L-Forms @ Loss of cell wall because murein for wall synthesis is absent @ Spheroplasts: gram negative L-forms @ Protoplasts: gram positive L-forms @ Origin: * Spontaneous (Streptobacillus, Bacteroides) * Presence of penicillin or lysozyme * Destruction of wall by complement * Absence of nutrient for wall synthesis @ No pathological or clinical significance.

7. Bacterial Cell Membrane Structure: @ Composed of 3 layers: @ 2 phospholipids layers with phosphate heads and lipid tails. @ They are hydrophilic at their phosphate heads and hydrophobic at their lipid tails. @ The hydrophobic lipid tails point inwards and the hydrophilic phosphate heads point outwards. @ Glycoproteins point outwards & attached to carbohydrate chain

9. @ Integral proteins help to anchor the cytoskeleton in place. @ Transmembrane proteins have enzymatic activity & catalyze chemical reactions @ The third layer is the hydrophobic region. @ It contains proteins (70%) and lipids (30%) @ ٍ CM: semipermeable to nutrients, water, salts @ Folded towards cytoplasm to form mesosome

11. Functions of Cell Membrane @ Forms an osmotic barrier between cytoplasm and environment @ Transport of: # Respiratory electrons # Nutrients inside cell. # Waste product outside cell @ Synthesis and transfer of peptidoglycan, teichoic acids, & other contents of cell wall @ Secretion of extracellular enzymes and toxins @ Segregation of chromosomal and plasmid DNA into daughter cells.

13. Mesosomes @ Mainly invaginations of cell membrane @ Functions include: # Involved in nuclear division # Provide respiratory enzymes # Excretion of material outside the cell # Involved in cell wall synthesis # Involved in cell wall division @ Convoluted & formed of lamellae or vesicles. @ Developed in mycobacteria, E. coli, Bacillus @ May join cell wall or nuclear body

15. Cytoplasm @ Contains: water, ions, metabolites, proteins, nucleic acids, storage granules, ribosomes. @ Ribosomes@ Ribosomes actively translating messenger RNAmessenger RNA into proteins.proteins @ Storage granules serve as reserves of energy and nutrients. @ Metachromatic (volutin) granules are reserves of high energy phosphates in corynebacteria. @ Contains the bacterial chromosome as a single circular molecule.

17. Bacterial Nucleoid @ Bacterial chromosomal DNA is not enclosed by an envelope @ The chromosomal DNA molecule is 1.6 mm in a form of coil. @ Plasmid is a separate DNA molecule that can replicate independently @ Plasmids are double-stranded and circular. Their number can range from 1 to thousands. @ Plasmids can integrate and replicate with bacterial cells.

19. Endospores @ Induced by: Changes of pH, temp., oxygen tension, nutrients, waste products, moisture, minerals (Ca ++, Mn, K). @ Differences from vegetative cells: # More resistant to heat, disinfectants, dryness, starvation # Low water content (5 - 20%) # Thick, impermeable coat # Low metabolic activity # Contain Ca ++ and dipicolinic acid

21. Endospore Structure @ Endospores form within a vegetative bacterial cell @ Exosporium: a thin delicate covering @ Spore coat: thick layer of protein & keratin @ Cortex: made of peptidoglycan @ Core wall @ Core: contains ribosomes and nucleoid

23. Cycle of spore formation and germination: @ Bacterium makes a copy of its chromosome DNA & the bacterial cell membrane begins invaginating inward until there’s a little daughter cell within the mother cell. @ Next, membrane of mother cell surrounds the daughter cell. Then two membrane layers will surround the daughter cell. @ Then a thick peptidoglycan wall forms and a tough outer protein coat forms around all daughter cell, which is now spore.