Domain Bacteria and Domain
BASIC
CHARACTERISTIC of Both:
Archaea
•Unicellular
•Heterotrophic or Autotrophic
•Prokaryotic
Bacteria:
Archaea
(salt)
- Halophiles
Eubacteria
“True Bacteria”
•
Archaea “Ancient”
- extremophiles
- Thermophiles,
- Methanogens
(anaerobic waste removal) (Hydrothermal
vents)
How do Bacteria and Archaea differ?
 Domain Bacteria
 Structural:
 Peptidoglycan in
cell wall
 Molecular:
 Simple RNA
polymerases
• Domain Archaea
• Structural:
• No
peptidoglycan in
cell wall.
• Molecular:
• Complex RNA
polymerase
 Gram staining is used to identify bacteria.
– Stains the peptidoglycan layer.
– Gram-positive = Stain color - purple, Thick
peptidoglycan cell wall
– Gram-negative = Stain color - Pink, Thin
peptidoglycan cell wall + outer membrane.
B.subtilis
E. coli
Gram-negative bacteria have a thin layer of
peptidoglycan and stain red/pink.
Gram-positive bacteria have a thicker
peptidoglycan layer and stain purple.
Why are some bacteria resistant to
certain antibiotics?
GRAM NEGATIVE
GRAM POSITIVE
How bacterial resistance occurs!
 Basic Bacterial Structure
pili
cell
membrane
Nucleic Acid
cell wall
Ribosome
Plasmid
flagellum
Bacteria are Classified by Shape and
Growth Pattern
– Bacillus = rod shaped
– Spirilla = spiral shaped
– Coccus = spherical shaped
- Diplo = pair
- Strepto = chain
- Staphylo = cluster
Test yourself…Classify these bacteria?
Diplococcus
Spirillus
Streptococcus
Streptobacillus
Genetic Variation in Bacteria
Transformation – Bacterial picks up free DNA and adds it in to its own
DNA.
Conjugation –One bacteria transfers DNA to another.
Mutation – Random change in a DNA sequence.
How are Bacteria helpful?
 Benefit to Ecosystems
 Decomposition (CO2)
 Chemical Cycling
 Fix nitrogen in the soil (air to soil)
 Cyanobacteria (photosynthesis)
 Bioremediation – The use of organisms to remove or
neutralize pollutants from a contaminated site
 Provide Nutrients:
 Digestion of food in gut
 Cheese, butter, yogurt, sauerkraut
How are bacteria harmful?
 Pathogens: Cause Disease
 Scarlet Fever - Streptococcus pyogenes
 Strep Throat – Streptococcus pyogenes
 Bacterial Meningitis - Neisseria meningitidis
 Lyme Disease - Borrelia burgdorferi
 Produce toxins
 Botulism
 Clostridium botulinum
 The chemical used in botox
 Food Spoilage
 Antibiotic Resistance
What do we use to fight
infection?
 Antibiotics
 Vaccines
 Antiseptic
Antibiotics Vs Vaccines
 Antibiotics only treat
bacterial infections
 Given after someone is
infected
 Prevents bacterial
growth
 Vaccines treat viral or
bacterial diseases
 Given prior to infection
 Is made up of a small
dose of the pathogen
 Creates antibodies to
fight future infections
Antibiotic Sensitivity
 Antibiotic Sensitivity - the susceptibility of bacteria
to antibiotic
 To test antibiotic sensitivity  Thin wafers containing an antibiotic are placed on an
agar plate that is growing bacteria. The bacteria are
can’t grow next to the antibiotic they are sensitive to.
 Zone of inhibition - area around antibiotic disc
where bacterial growth is inhibited.
 Antibiotic Resistance - No clear zone (indicate antibiotic
resistance)
 Antibiotic discs are identified by the letter on the top.
Antibiotic
Identifier
Penicillin
P
Chloramphenicol
C
Doxycycline
D
Streptomycin
S
Ciprofloxacin
CIP
Control
CNTL
CNTL
Zone of
inhibition
4 cm
D
2cm
P
5 cm
C
1 cm
S
4 cm
CIP
1 cm
S
4 cm
0 cm
P
CIP
3 cm
C
CNTL
2 cm
D