Bacteria How they differ from us

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Bacteria How they differ from us

• Chapter 21

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What is Bacteria?

• Oldest life form
• Kingdom Monera
• Cell type is Prokaryote
• Grows on agar

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Their Negative Impact?
botulism

• Disease-causing
• Metabolize host
• Produce toxins

tuberculosis
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Compare bacteria cell to our cell
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List the main differences

• Eukaryotes
• Roughly (if a spherical cell)           10 times
  the diameter          100 times the surface
  area        1000 times the volume of a
  prokaryote.
• DNA is in paired chromosomesDNA is in a nucleus
  contained in a membrane
• Larger ribosomes
• Contain additional structures such as
  Mitochondria        Chloroplasts that
  are "live-in" prokaryotes
• Have additional structures to help with
  cell organization and functioning

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Eukaryote Cell Structure
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• Prokaryotes
• About one tenth the size of a eukaryote  
• DNA is a loopDNA floats in the cytoplasm
• Small ribosomes
• some are anaerobic (poisoned by oxygen)some can
  live with oxygen or without itsome use oxygen
• have a lot of biochemical diversity

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Bacterial Structures

• Flagella
• Pili
• Capsule
• Plasma Membrane
• Cytoplasm
• Cell Wall
• Lipopolysaccharides
• Teichoic Acids
• Inclusions
• Spores

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Shapes of Bacteria

• Coccus
• Chain Streptoccus
• Cluster Staphylococcus
• Bacillus
• Chain Streptobacillus
• Coccobacillus
• Vibrio curved
• Spirillum
• Spirochete

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Flagella

• Motility - movement
• Swarming occurs with some bacteria
• Spread across Petri Dish
• Proteus species most evident
• Arrangement basis for classification
• Monotrichous 1 flagella
• Lophotrichous tuft at one end
• Amphitrichous both ends
• Peritrichous all around bacteria

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Pili

• Short protein appendages
• smaller than flagella
• Adhere bacteria to surfaces
• E. coli has numerous types
• K88, K99, F41, etc.
• Antibodies to will block adherance
• F-pilus used in conjugation
• Exchange of genetic information
• Flotation increase boyancy
• Pellicle (scum on water)
• More oxygen on surface

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F-Pilus for Conjugation
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Capsule or Slime Layer

• Glycocalyx - Polysaccharide on external surface
• Adhere bacteria to surface
• S. mutans and enamel of teeth
• Prevents Phagocytosis
• Complement cant penetrate sugars

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Cell Wall

• Peptido-glycan Polymer (amino acids sugars)
• Unique to bacteria
• Sugars NAG NAM
• N-acetylglucosamine
• N-acetymuramic acid
• D form of Amino acids used not L form
• Hard to break down D form
• Amino acids cross link NAG NAM

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Cell Wall Summary

• Determine shape of bacteria
• Strength prevents osmotic rupture
• 20-40 of bacteria
• Unique to bacteria
• Some antibiotics effect directly
• Penicillin

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Gram Staining
Bacteria are small and transparent so how to
see? Place a slide with a bacterial smear on a
staining rack. STAIN the slide with crystal
violet for 1-2 min. Pour off the stain.Note
fingers stain Gram-positive - use forceps! Flood
slide with Gram's iodine for 1-2 min. Pour off
the iodine. Decolourize by washing the slide
briefly with acetone (2-3 seconds). Wash slide
thoroughly with water to remove the acetone - do
not delay with this step. Flood slide with
safranin counterstain for 2 min. Wash with
water. Blot excess water and dry in hand over
bunsen flame. http//www.microbiologybytes.com/vi
deo/Gram.html
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Classify these
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Endospores

• Resistant structure
• Heat, irradiation, cold
• Boiling gt1 hr still viable
• Takes time and energy to make spores
• Location important in classification
• Central, Subterminal, Terminal
• Bacillus stearothermophilus -spores
• Used for quality control of heat sterilization
  equipment
• Bacillus anthracis - spores
• Used in biological warfare

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Classify These
anthrax