Bacterial Structure(2)
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Size of Bacteriay Average bacteria 0.5 - 2.0 um in diam.
y RBC is 7.5 um in diam.
y Surface Area ~12 um
y Volume is ~4 um
y Surface Area to Volume is 3:1
y Typical Eukaryote Cell SA/ Vol is 0.3:1
y Food enters through SA, quickly reaches all parts of bacteria
y Eukaryotes need structures & organelles
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Size of Bacteriay Average bacteria 0.5 - 2.0 um in diam.
y RBC is 7.5 um in diam.
y Surface Area ~12 um
y Volume is ~4 um
y Surface Area to Volume is 3:1
y Typical Eukaryote Cell SA/ Vol is 0.3:1
y Food enters through SA, quickly reaches all parts of bacteria
y Eukaryotes need structures & organelles
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Shapes of Bacteriay
Coccus
y Chain = Streptoccus
y Cluster = Staphylococcus
y Bacillus
y Chain = Streptobacillus
y Coccobacillus
y Vibrio = curved
y Spirillum
y Spirochete
y Square
y Star
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Square shaped
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Grouping of BacteriaGrouping of Bacteria
y Diplo- Groups of two
y Strepto- chains
y Staphylo- Grape like clusters
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Bacterial Structures
y Flagella
y Pili
y Capsule
y Plasma Membraney Cytoplasm
y Cell Wall
y Lipopolysaccharides
y Teichoic Acids
y Inclusions
y Spores
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Flagella
y Motility - movement
y Swarming occurs with some bacteria
y Spread across Petri Dish
y Proteus species most evident
y Arrangement basis for classification
y Monotrichous; 1 flagella
y Lophotrichous; tuft at one end
y Amphitrichous; both ends
y Peritrichous; all around bacteria
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Piliy Short protein appendagesy smaller than flagella
y Adhere bacteria to surfaces
y E. coli has numerous typesy K88, K99, F41, etc.
y Antibodies will block adherance
y F-pilus; used in conjugation
y Exchange of genetic information
y Flotation; increase boyancy
y Pellicle (scum on water)
y More oxygen on surface
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Capsule or Slime Layery Glycocalyx - Polysaccharide
on external surface
yAdhere bacteria to surfacey enamel of teeth
y Prevents Phagocytosis
y Complement cant penetrate
sugars
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Cytoplasm
y 80% Water {20% Salts-Proteins)
y Osmotic Shock important
y DNA is circular, Haploid
y Advantages of 1NDNA over 2NDNA
y More efficient; grows quicker
y Mutations allow adaptation to
environment quicker
y Plasmids; extra circularDNA
y Antibiotic Resistance
y No organelles (Mitochondria, Golgi, etc.)
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Cell Membraney Bilayer Phospholipid
y Water can penetrate
y Flexible
y Not strong, ruptures easily
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Chapter 4
Functions of the cytoplasmic membrane
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Cell Wally Peptido-glycan Polymer (amino acids + sugars)
y Unique to bacteria
y Sugars; NAG & NAM
y N-acetylglucosamine
y N-acetymuramic acid
y D form of Amino acids used not L form
y Hard to break down D form
y Amino acids cross linkNAG & NAM
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Teichoic Acidsy Gram + only
yGlycerol, Phosphates, & Ribitol
y Attachment for Phages
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Lipopolysaccharide (LPS)y Endotoxin or Pyrogen
y Fever causing
y Toxin nomenclature
y Endo- part of bacteriay Exo- excreted into environment
y Structure
y Lipid A
y Polysaccharidey O Antigen of E. coli, Salmonella
y G- bacteria only
y Alcohol/Acetone removes
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LP
S (contd)y Functionsy Toxic; kills mice, pigs, humans
y G- septicemia; death due to LPS
y Pyrogen; causes fever
y DPT vaccination always causes fevers
y Adjuvant; stimulates immunity
y Heat Resistant; hard to remove
y Detection (all topical & IV products)
y Rabbits (measure fever)
y
Horse shoe crab (Amoebocytes Lyse in presence of LPS)
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LPS (contd.)y Appearance of Colonies
y Mucoid = Smooth (lots of LPS or capsule)
y Dry = Rough (little LPS or capsule)
y O Antigen of Salmonella and E. coli
y2,000 different O Ags of Salmonella
y 100s different O Ags of E. coli
y O Ags differ in Sugars, not Lipid A
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Endospores
y Resistant structure
y Heat, irradiation, cold
y Boiling >1 hr still viable
y Takes time and energy to make spores
y Location important in classification
y Central, Subterminal, Terminal
y Bacillus stearothermophilus -spores
y Used for quality control of heat sterilization equipment
y Bacillus anthracis - spores
y Used in biological warfare
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G+ vs. G-y G+
y Thicker cell wall
y
Teichoic Acids
y G-
y Endotoxin - LPS
yWhich are more sensitive to Penicllin?
yAlcohol/Acetone affects which more?
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Prokaryotes vs. Eukaryotesy Cell Wall
y
Teichoic Acidsy LPS
y Endospores
y Circular DNA
y Plasmids
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Eukaryote Cell Structure