Transcript Bacteria

Eubacteria
Bacteria – Kingdom Eubacteria
• Oldest, most
abundant and
diverse group of
living organisms
Characteristics
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Single cell
Prokaryotic
Single chromosome
No membrane bound
organelles
• Reproduce sexually
and asexually
Structure
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Capsule  protect against
WBC, cling to surface,
protect from drying out
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Cell wall maintain shape
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Nucleoid  circular mass of
DNA
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Plasmid  single circular DNA
strand used in
conjugation
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Pili  attachment to host cell
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Flagellum  motion (whip)
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Ribosomes  make protein
How big are bacteria?
Classification
• Based on
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Shape
Arrangement
Cell wall structure
Carbon and energy
source
– Oxygen requirements
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Shape
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Spherical
Cocci (pl)
Cocus (sing)
Rod shaped
Bacilli (pl)
Bacillus (sing)
Spiral
Spirilla (pl)
Spirillum (sing)
Arrangement
• Prefix
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Diplo – twos
Staphylo – cluster
Strepto  chains
Sarcina  octets
Tetrad  fours
Cell wall structure
Peptidoglycan
– Thin sheet composed of 2 sugar derivatives
and a small group of amino acids that make
up the cell wall
– Formation is disrupted by penicillin
Gram Positive vs. Gram Negative
Gram Positive
– Thick protein layer on cell
wall
– Stain deep purple
– 90% of wall is made of
peptidoglycan
• Gram Negative
– Thin protein layer on cell
wall
– 5-20% made of
peptidoglycan (penicillin is
not as effective)
– Stain pink
– Lipopolysaccharide layer on
outside of cell wall acts as a
permeability barrier
Gram Positive vs. Gram Negative
Carbon and Energy Source
Oxygen Requirements
• Obligate Aerobes
– require O2 for survival
– e.g. pneumonia, tuberculosis
• Obligate Anaerobes
– O2 not required for survival
– e.g. food poisoning, tetanus bacteria
• Facultative aerobes
– mainly function in the absence of oxygen; can
function in the presence of O2
• Facultative anaerobes
– grow best in presence of oxygen; can function in
absence
– e.g. scarlet fever, typhoid fever, E. coli in human
intestines
Reproduction in Bacteria
• Binary Fission  asexual reproduction
• Conjugation  sexual reproduction
Binary Fission - Video
Conjugation - Video
Bacterial Growth
• Exponential Growth
• Limited by the exhaustion of nutrients or
accumulation of toxic products
Comparing Eubacteria &
Archaebacteria
Similarities
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Prokaryotic single celled
No membrane bound organelles
Single chromosome
Reproduce asexually by binary fission
DIFFERENCES
Eubacteria
– Cannot tolerate
high temp
– Aerobic/anaerobic
Archaebacteria
– Found in swamps, high
salt concentration,
high temp., high
acidity
– Anaerobic (most)
How are bacteria similar to and
difference from viruses?
Similar  have genetic material,
pathogenic (some)
Different  bacteria are capable of
independent life
Eubacteria and archaebacteria
reproduce using binary fission.
How is this process different from
mitosis?
• Much simpler, only single strand of DNA is
replicated  no lining up along equator,
spindle fibers, etc.
Explain how bacteria share genetic
information
Conjugation
• make contact with cytoplasmic bridge
(pillus)
• Plasmids are transferred from the
donor to the recipient
Describe two beneficial effects of bacteria and two
harmful effects of bacteria. Include examples
Beneficial:
1. Flavobacterium:
– dismantle complex penta molecules, leaving
non-toxic CO2 + H2O and harmless
chlorides.
2. Streptomyces – source of antibiotics
Harmful:
1. legionella pneumophilia:
Legionnaire’s disease
2. E.coli 157 in Walkerton
What is an antibiotic?
• chemicals produced synthetically or by
microorganisms that inhibit the growth
of or destroy certain other
microorganisms
How does bacterial resistance to
antibiotics develop?
Resistance
 genetic variation allows some to survive
 pass on R (resistance) factor to next
generation as well as through
conjugation
 R factor increases population