Microbio Ch 4 – Flashcards
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| Basic Shapes |
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| Spehrical / Cubical / Cylindrical |
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| Internal Content |
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| cytoplasm (surrounded by a membrane) , DNA chromosomes, ribosomes, metabolic capabilities |
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| two basic cell types |
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| eukaryotic and prokaryotic |
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| eukaryotic cells are found in |
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| animal cells, plant cells, fungal cells, and protista cells |
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| prokaryotic cells are in |
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| bacteria and archaea do not contain a nucleus or other membrane-bound organelles |
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| two major groups of appendages |
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| motility - flagella and aial filaments / attachment or channels - fimbriae and pili |
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| glycocalyx |
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| surface coating |
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| flagella has 3 parts |
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| Filament – long, thin, helical structure composed of protein flagellin; Hook – curved sheath ; Basal body – stack of rings firmly anchored in cell wall |
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| chemotaxis |
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| chemical stimuli ; moves towards or away from chemical stimulant |
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| phototaxis |
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| light stimuli ; moves towards or away from light stimulant |
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| flagella counterclockwise movement |
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| results in smooth linear directioin "run" |
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| flagella clockwise movement |
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| tumble |
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| fimbriae |
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| fine, proteinaceous, hair - like bristes emerging from the cell surface |
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| fimbriae functions |
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| adhesion to other cells and surfaces |
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| pili |
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| rigid tubular structure made of pillin protein ; found only in gram negative cells |
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| pili functions |
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| joins bacterial cells for partial DNA transfer (conjugation) |
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| two types of coatings |
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| slime layer - loosely organize and attached ; capsule -highly organized, tightly attached |
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| glycocalyx function |
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| protects cells from dehydration and nutrient loss ; inhibit killling by white blood cells by phagocytosis ; contributes to pathogenicity ; formation of biofilms |
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| cell wall |
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| External covering outside the cytoplasm; Maintains cell integrity |
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| cell wall functions |
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| Determines cell shape, prevents lysis due to changing osmotic pressures |
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| gram positive bacteria |
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| thick cell wall composed primarily of peptidoglycan and cell membrane |
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| gram negative bacteria |
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| : outer cell membrane, thin peptidoglycan layer, and cell membrane |
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| peptidoglycan |
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| primary component of cell wall; unique macromolecule ; a repeating framework of long glycan chains cross-linked by short peptide fragments |
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| gram positive cell walls |
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| Attach layers of peptidoglycan to each other and to cell membrane ; function in cell wall maintenance and enlargement during cell division; move cations across the cell envelope; stimulate a specific immune response |
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| gram negative cell walls |
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| Made up of three distinct levels: ; The outer membranes – LPS ; Lipid portion (endotoxin) may become toxic when released during infections ; May function as receptors and blocking immune response ; Contain porin proteins in upper layer – regulate molecules entering and leaving cell |
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| periplasmic space |
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| between the LPS and the cell membrane; a thin layer of peptidoglycan in the periplasmic space |
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| gram positive stain |
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| - retain crystal violet and stain purple |
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| gram negative stain |
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| lose crystal violet and stain red from safranin counterstain |
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| non-typical cell walls |
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| Some bacterial groups have extra ingredients in their cell wall: Mycobacterium and Nocardia ; G +ve cell wall structure with lipid mycolic acid (cord factor) ; Pathogenicity and high degree of resistance to certain chemicals and dyes; Basis for acid-fast stain used for diagnosis of infections caused by these microorganisms ; Some have no cell wall, i.e., Mycoplasma ;Cell wall is stabilized by sterols; “Pleomorphic” |
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| cell membrane structure |
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| Phospholipid bilayer w/proteins – fluid mosaic model |
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| cell membrane structure functions |
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| Providing site for ETC, nutrient processing, and synthesis ; Passage of nutrients into the cell and discharge of wastes ; Cell membrane is selectively permeable |
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| cytoplasm |
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| Dense gelatinous solution of sugars, amino acids, and salts ; 70-80% water ; Serves as solvent for materials used in all cell functions |
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| chromosome |
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| Single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell |
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| plasmids |
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| Free small circular, double-stranded DNA ; Not essential to bacterial growth and metabolism ; Used in genetic engineering - readily manipulated and transferred from cell to cell |
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| ribosomes |
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| made of 60% ribosomal RNA and 40 protein ; consists of two subunits ; prokaryotic differ from eukaryotice ribosomes in size and number of proteins ; site of protein synthesis ; found in all cells |
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| cytoskeleton |
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| Many bacteria possess an internal network of protein polymers that is closely associated with the cell wall |
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| endospores |
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| Inert, resting, cells produced by some G+ genera: Clostridium, Bacillus, and Sporosarcina; Have a 2-phase life cycle: ; Vegetative cell – metabolically active and growing; Endospore – when exposed to adverse environmental conditions; capable of high resistance and very long-term survival |
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| sporulation |
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| formation of endospores ; Hardiest of all life forms; Withstands extremes in heat, drying, freezing, radiation, and chemicals ; Not a means of reproduction |
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| germination |
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| return to vegetative growth |
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| endospores |
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| Dehydrated, metabolically inactive ;Thick coat; Longevity verges on immortality, 250 million years; Resistant to ordinary cleaning methods and boiling ; Pressurized steam at 120oC for 20-30 minutes will destroy – autoclave! |
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| pleomorphism |
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| Variation in cell shape and size within a single species ;Some species are noted for their pleomorphism |
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| classification system for prokaryotes based on |
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| microscopic morphology / macroscopic morphology / baterial physiology / serological analysis / genetic and molecular analysis |
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| phylum proteobacteria |
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| gram negative cell walls |
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| phylum firmicutes |
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| mainly gram positive with low G + C content |
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| phylum actinobacteria |
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| gram positive with high G + C content |
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| species |
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| a collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly |
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| strain or variety |
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| a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars) |
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| type |
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| a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype |
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| photosynthetic bacteria |
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| use photosynthesis, can synthesize required nutrients from inorganic compounds; Cyanobacteria (blue-green algae) ; Green and purple sulfur bacteria ; Gliding, fruiting bacteria |
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| cyanobacteria |
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| Gram-negative cell walls ;Extensive thylakoids with photosynthetic chlorophyll pigments and gas inclusions |
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| green and purple sulfur bacteria |
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| Photosynthetic ; Contain photosynthetic pigment bacteriochlorophyll ; Do not give off oxygen as a product of photosynthesis |
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| gliding and fruiting bacteria |
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| gram negative and glide over moist surfaces |
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| archaea ; the other prokaryote |
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| Constitute third Domain Archaea ; More closely related to Eukarya than to Bacteria ; Contain unique genetic sequences in their rRNA ; Have unique membrane lipids and cell walls |
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| archaea |
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| Live in the most extreme habitats in nature, extremophiles ; Adapted to heat, salt, acid pH, pressure, and atmosphere ; Includes: methane producers, hyperthermophiles, extreme halophiles, and sulfur reducers |
