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Download Microbiology – Alcamp Lecture: Bacterial Structures
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Transcript
Microbiology – Alcamo Lecture: Bacterial Structures -Not all bacteria have all structures Shapes of Bacteria • _______ Different Shapes: Bacilli • _______ shaped • Most occur singly, but some form long chains called _____________ • Examples: – __________ _________ – __________ – __________ Cocci • Usually ______ shaped but can be oval • Diplococci – cocci that remain in _____ – Examples – Gonorrhea, Menengitis • Streptococci – cocci in __________ – Examples - Strep throat, Tooth decay • Staphylococcus – irregular __________ __________ of cells – Examples – Food poisoning, staph skin infections Spiral Bacteria • __________ – curved rods - look like a comma – Example - Cholera • __________ – corkscrew shape with flagella – Example – Rat Bite fever • __________ – corkscrew shape but no flagella – Example - syphilis Flagella • Used by some bacteria to achieve _________ • Made of long rigid strands of protein called __________ • Protein strands are permanently ________ • Permits the flagellum to rotate and ________ the bacterium forward Flagella • Complicated structure: Filament attached to hook-like shaft which is inserted through cell wall and attached to cell membrane Flagella _______trichou s _______trichou s _______trichou s Axial Filament • • • Only ____________ One flagella attached at both ends of flexible spiral MO Motion effected by cell spinning around filament Pili • • Look like short flagella but have nothing to do with _________ Very tiny protein “Hairs” that enable MO to ________ to surfaces - like “Velcro” Pili • Pili aid in transfer of ___________ __________ between bacteria • Pili anchor bacteria to surfaces like _________ ________ • Can __________ MO’s disease effect • Example - gonorrhea Capsule • Some bacteria secrete a layer of _____________ and ___________ that stick to its surface • Sticky and gelatinous • Serves as a buffer between the bacteria and its environment – Protects bacteria against ______________ – Protects bacteria against host’s _________ _____________ White Blood Cell Glycocalyx • Some bacteria produce a _______ _______ • Complex _____, made inside cell wall secreted as liquid, polymerizes to jelly like substance _________ – S. mutans attaches itself to teeth by using the sugar a person eats – creates an acid that breaks down tooth enamel • Cell Wall • All bacteria have a cell wall except mycoplasmas • Semi-rigid structure, _________, gives _________ • Amount of chemical “_____________” determines characteristics of cell wall • If a lot: Thick, G+ stain reaction, sensitive to penicillin and lysozyme in tears, saliva, mucous •If small: thinner, G- stain reaction, not sensitive to penicillin or lysozyme •If MO is pathogenic, disease more difficult to cure Cell Membrane • • • • Boundary layer of the cell ________ of cell wall Contains _________, controls _________ ________ in and out of the cell Triple layer structure, 60% proteins, 38% lipids (phospholipid bilayer), 2% sugars Antimicrobials (detergents, alcohol, some antibiotics) __________ cell membrane cell membrane animation Cytoplasm Gelatinous mass of ________ carbohydrates ________ nucleic acids ________ ions ________ Important Structures in Cytoplasm • Ribosomes – ________ __________ • Inclusion Bodies – globules of starch or lipids – ________ _________ • Bacterial Chromosome – closed loop of DNA ________ a membrane or proteins (nucleoid region) • Plasmids – smaller, separate _________ __ ______ – few genes but do give bacteria drug resistance (R genes) Endospores • Some Gram + bacteria produce highly resistant structures - ___________ – – – – Bacteria grow, mature and reproduce as _____________ cells Then the bacterial chromosome replicates and the cell membrane grows in to _______ ______ a developing spore Next, thick layers of peptidoglycan form to _________ the cell Finally, the cell wall of the vegetative cell disintegrates and the spore is __________ Endospores • Very resistant to poor environmental conditions: – ________ _____________– boiling water – ____________ – 70% alcohol – Spores have even been recovered alive from an Egyptian mummy’s intestines • Examples of spore formers – anthrax, botulism, tetanus •“__________” is spore formation DNA + some cytoplasm wrapped in spore case formed by cell membrane •“__________” occurs when good environmental conditions return – vegetative cell Kingdom Classification Archaeobacteria • Have existed on earth longer than any other living organism • They are different from eubacteria: – No ______________ in cell wall – Different _________ in cell membrane – Different ribosomal ________ – Now archaeobacteria and eubacteria are classified as different kingdoms Archaeobacteria • 3 Types: – _______________ – rods that live in anaerobic conditions and produce methane gas – common in marshes and the guts of cows and humans – ________________ – resistance to acid and high temperatures – live in hot springs and ocean vents – ___________ ____________– thrive in high salt environments (Great Salt Lake)
