EBIO 3400 1st Edition Lecture 5Outline of Last Lecture I. Mapping microbial diversity onto the tree of lifeOutline of Current Lecture II. Cell wall cont.III. CapsuleIV. Prokaryotic Cell structureV. Flagella and motility Current LectureI. Cell wall Continued.. A. Sacculus: bacterial cell wall, single interlinked moleculei. Isolated in E. ColiB. N-acetylglucosamine: aka chitin that exists in many exoskeleton of many arthropods and also in the cell walls of many fungii. Found in all three domains but barely in archaeaii. Plants have cellulose instead of chitin because plants can’t afford using nitrogen in their cell walls. Plants have cell walls that is more similar to fungiC. Archaeal cell wallsi. Do not contain peptidoglycan but a few use N-acetylglucosamine in pseudopeptidoglycanii. No D-amino acids (bacteria use some D-amino acids in their cell walls) D. Two types of main bacterial cell walls1) Gram-positive: have multiple layers of peptidoglycan threaded by teichoic acids. Teichoic acids consists of glycerol chainsi. Have an S-layer that is an additional protective layer found in some free-living bacteria and archaea. ii. S-layer is a crystalline layer of thick subunits consisting of protein or glycoproteiniii. May contribute to cell shape and help protect the cellfrom osmotic stress. Often have pores in itThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2) Gram-negative: the thin peptidoglycan layer consists of one or twosheetsi. Covered by an outer membrane that presents defensive abilities and toxigenic properties on many pathogens ii. Outward-facing leaflet contains: lipopolysaccharides and porins iii. Periplasm: area between two membranes, inside worldof cytoplasm with extracellular proteins in there. Prettyactive layer but bigger molecules can’t travel through the porins (trapped) water can move through osmosis anywhere 3) LPS: lipopolysaccharides are the outermost part of the cell envelope. Long chain polysaccharides that stick out to the outer world. Anti-genic immune system recognizes these bacteria. Also called o-polysaccharides- Often charged and interacted with water (tail)- Lipid A endotoxic, gram-negative, we would killthese in our system and when they die they destroy this membrane and it releases toxin lipid A which may be the cause of most diseases todayPossible exam questions4) How does the gram stain work?Gram-positive: thick peptidoglycan so prevents the crystal violet form escaping Gram negative: outer membranes dissolved and peptidoglycan toothin to retain the crystal violet 5) Which would resist drying better, the gram + or gram -?The gram positive because it is thicker so the cell wall is less flexible and rigid6) Why do gram + bacteria dominate soil and terrestrial environments?Gram + don’t dry out as easily because of the thicker cell wall so it resists drying. Bacteria in the soil go through huge cycles of being dry and wet so must withstand those two conditions7) Why do gram – bacteria dominate aquatic environments?Gram – are usually in isotonic solutions so has a membrane perfect for interacting with aquatic – more changeable, adaptable,permeable. They also can change the number of porins they have II. Capsules (glycocalyx) - Made of polysaccharide and/or glycoproteins - Protects cells from phagocytosis, drying – attachment to surfaces and other cells- Found in come gram+ and gram- species but not all - Outside the S-layer, outer membrane- Gooey mass that protects the cellA. Negative stain: colors the background, which makes the capsule more visible - Pathogens linked to capsules ex. Streptococcus pneumoniaeB. Mycobacterial cell walls (gram +)i. Mycobacterium tuberculosis and M. leprae have very complex cell envelopes- Include unusual membrane lipids (mycolic acids) and unusual sugars (arabinogalactans) - Have many different layers of polysaccharides, very complex cell walls ii. Mycobacterium tuberculosis causes tuberculosis (gram +) –waxy and crinkled appearance- Some gram + bacteria have other compounds associated with their cell walls, mycobacterium spp. Produce numerous amounts of mycolic acid (hydrophobic chains of 60-90 carbon atoms) that coats the cells protecting them from the immune system and drying - These colonies are just adapted to survive, take in nutrients and are slow growing pathogensIII. Prokaryotic cell structure Have filamentous protein appendagesA. FlagellaB. Fimbriae: straight filaments of pilin protein –used to attach to surfaces and ther cells (e.g. in Neisseria gonorrhoeae use them to attach to human mucosal cells)C. Pili: larger, genetically determined by sex factors and used for matingD. Sex pili: used in conjugation (connection between things)E. Stalks: membrane embedded extensions of the cytoplasm, the tips secrete adhesion factors called holdfasts F. Nanotubes: intercellular connections that pass material from one cell to the next (e.g. Bacillussubtilis)Key note: they can be antigenic (repeating proteins are fairly good antigens) – cause an immune response and the production of specific antibodies IV. Flagella & motilityUsed for locomotion Flagella are distributed in specific patterns: 1) Monotrichous and polar: 12) Lophotrichous: many on one side3) Amphitrichous: 2 on each end4) Peritrichous: spread around the organism Rotary Flagella Prokaryotes that are motile swim with this flagella that rotates together in a bundle behind the swimming cell – like a cork screwViscous world so move through molecules using friction (helix that moving)Composed of: the filament, the basal body, the