BIOL 209 1st Edition Lecture 5 Outline of Last Lecture I. The Cell WallA. Question/answerB. Bacterial Cell WallC. Question/answerD. Non-typical Cell WallsII. EnvelopesA. Gram +B. Gram – III. Cell Wall StainingA. Gram StainingB. Acid-Fast StainingOutline of Current Lecture I. Question/Answer’sII. FlagellaA. Structure & Function1. Conjugation pili2. FimbriaeB. MovementIII. Pili & FimbriaeA. Structure & FunctionIV. GlycocalyxA. Structure & FunctionV. BiofilmsVI. Interior Bacterial StructuresA. Bacterial NucleoidB. RibosomesC. EndosporesCurrent LectureI. Question/Answer’sA. Question: What role do you think appendages (flagella, pili, fimbriae, glycocalyx, and biofilms) play in pathogenesis? Answer: Movement and adherence for an ideal place to growB. What characteristic of bacterial flagella is regulated in order to control cell movement? Answer: Direction of rotationThese 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.C. What is the advantage to the bacteria of coordinated expression? Answer: Acting together to coordinate activities  more powerD. Where else would you find biofilms besides catheters? Shower curtains, dental plaqueII. FlagellaA. Provide mobility and sometimes adherence1. One or many flagella may be present2. They can have a polar location, or be disturbed (one place or all over)a. Locations don’t changeB. Structure1. Filament (made of protein – bulk of flagella), hook, basal body (“motor” – rotates by use of a proton gradient)C. Movement1. Type depends on direction of flagella rotationa. Counter-clockwise (CCW): smooth running movementb. Clockwise: tumbling movement2. Random walk: Alternative running/tumblinga. Running moves cell forward, switch to clockwise rotation causes tumbling b. Overall choice of direction is random3. Chemotaxis: a biased random walka. Receptors bound by attractants prolong CCW rotation of flagella (running)- The higher the attractant concentration, the longer the time spent in run mode – this results in movement toward area of highest attractant concentration- CCW moves cell toward attractantIII. Pili & FimbriaeA. Structure & Function1. Conjugation pili: long protein fibers allowing adhesion between bacterial cells a. Conjugation allows transfer of DNA between bacterium2. Fimbriae (sometimes called “pili”): short protein fibers contributing to adherence to inanimate surfaces, other microorganisms, and sometimes select host tissuesa. Production of certain types of fimbriae can determine binding to specific host cells and can be the difference between pathogenic & non- pathogenic strains- Specificity in shape & attachment sitesIV. GlycocalyxA. Structure & Function1. Secreted carb & protein layer outside the cell envelope2. Helps retain water and nutrients, acts as an adherenta. Slime layer: loosely associated glycocalyxb. Capsule: thicker glycocalyx associated closely with the envelope- Can provide protection by blocking phagocytosis by host immune cellsV. BiofilmsA. Structure & Function1. Complex communities of microbes that adhere to a surface and each other through production of a thick/sticky slime layer2. Highly resistant to physical and chemical treatments, including many host immune mechanisms3. Close proximity of cells can promote transfer of genetic info4. Bacteria in biofilm respond to presence of a secreted inducer and coordinately express digestive enzymes or toxinsVI. Interior Bacterial StructuresA. Bacterial nucleoid occupies up to ½ of interior space of cell1. The genome is compacted by binding to histone-like proteinsa. Ribosomes occupy much of the remaining spaceB. Ribosomes produce cell proteins by translation of mRNA1. Prokaryotic ribosomes: 3 rRNAs + 55 ribosomal proteins2. Also found as polyribosomes: multiple ribosomes translating an individual mRNAC. Endospores1. A number of pathogenic bacteria produce endosporesa. Extremely resistant to destruction and provide a ready source of infection2. Endospores have a copy of the bacterial genome surrounded by a tough protein coat that includes dipicolinic acid and calcium 3. Spores are not metabolically active a. Bacterial sporulation is NOT reproductive - it is strictly a survival strategyDepletion of nutrients induces sporulation – Spore forms within mother cell, which then deteriorates – H2O and the presence of small nutrient molecules induces