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Diversity of Life -
Prokaryotes
What are prokaryotes?
- a type of organism lacking a membrane-enclosed nucleus
and membrane-enclosed organelles.
What are prokaryotes?
- a type of organism lacking a membrane-enclosed nucleus
and membrane-enclosed organelles.
Bacteria
What are prokaryotes?
- a type of organism lacking a membrane-enclosed nucleus
and membrane-enclosed organelles.
Bacteria
Archaea
What are the features of prokaryotes? Look at:
1.  Cell surfaces
2.  Internal organization
3.  Nutritional/metabolic adaptations
What are the features of prokaryotes? Cell Surfaces
-one feature which determines the kind of bacterium
being dealt with
-made up peptidoglycan
Sugars (polymers)
Polypeptides
What are the features of prokaryotes? Cell Surfaces
-one feature which determines the kind of bacterium
being dealt with
peptidoglycan layer
plasma membrane
Cell wall = peptidoglycan layer
What are the features of prokaryotes? Cell Surfaces
-one feature which determines the kind of bacterium
being dealt with
lipopolysaccharide
Outer membrane
peptidoglycan layer
plasma membrane
Cell wall = peptidoglycan layer
Cell wall = peptidoglycan layer
+ outer membrane
What are the features of prokaryotes? Cell Surfaces
-one feature which determines the kind of bacterium
being dealt with
lipopolysaccharide
Outer membrane
peptidoglycan layer
plasma membrane
Cell wall = peptidoglycan layer
Gram positive
Cell wall = peptidoglycan layer
+ outer membrane
Gram negative
What are the features of prokaryotes? Gram positive
Gram negative
What are the features of prokaryotes? Cell surfaces and infection
-lipopolysaccharide layer - can produce toxins
-outer membrane - protects bacteria from host’s
immune system
- outer membrane - protects bacteria from
antibiotics
What are the features of prokaryotes? Internal structure
cell wall
nucleoid region
plasmids
plasma membrane
ribosomes
capsule
chromosome
Prokaryotic cell
What are the features of prokaryotes? Internal structure - what do the structures do?
Cell wall - provides physical protection, maintains shape in different salinities
Capsule - sticky, polysaccharide or protein - protection from host’s immune system
Plasma membrane - acts as a selective chemical barrier
Chromosome - a ring of DNA that carries all the necessary genetic information
Nuceloid region - area of the cell containing the chromosome
Plasmids - small rings of DNA - function in ‘emergency’ situations
Ribosomes - site of protein synthesis in the cell
What are the features of prokaryotes? Nutritional and metabolic adaptations
Ways of obtaining energy
Autotroph - use only CO2 as a carbon source
Heterotroph - need one organic nutrient (e.g. glucose)
Phototrophs - use light as a source of energy Chemotrophs - use chemicals as a source of energy
What are the features of prokaryotes? Nutritional and metabolic adaptations
Ways of obtaining energy
Mode of nutrition Energy source Carbon source Light
Inorganic
CO2
CO2
chemicals
Light
Organic
Autotrophs
Photoautotroph
Chemoautotroph
Heterotrophs
Photoheterotroph compounds
Chemoheterotroph compounds
Organic Organic
compounds
What are the features of prokaryotes? Nutritional and metabolic adaptations
Relationship to Oxygen
Facultative
Aerobes
Anaerobes
Obligate
None
Need O2 for cellular
respiration
Use O2 for cellular
respiration but can
grow without it
Poisoned by O2 -use other chemicals
What are the features of prokaryotes? Nutritional and metabolic adaptations
Relationship to Nitrogen
N2
NH3
Amino acids
Proteins
Plant can’t fix N2
Classification of Prokaryotes
What features separate the Bacteria from the Archaea?
Characteristic
Bacteria
Arachaea
Peptidoglycan
yes
no
Reponse to
antibiotics
growth
inhibited
growth
not inhibited
no
some species
Growth above
100ºC
See Table 27.2 in your book
Classification of Prokaryotes
Alpha
Beta
Gamma
Delta
Proteo-
bacteria
Epsilon
Chlamydias
Spirochaetes
Cyanobacteria
Gram positive bacteria
Archaea
Classification of Prokaryotes
Alpha
Gram positive
Beta
Gram negative
Gamma
Delta
Proteo-
bacteria
Epsilon
Chlamydias
Spirochaetes
Cyanobacteria
Gram positive bacteria
Archaea
Classification of Prokaryotes
Alpha Proteobacteria
-e.g. Rhizobium - nitrogen fixing in plant roots
Beta Proteobacteria
-several soil bacteria
Gamma Proteobacteria
-some pathogens Salmonella (food poisoning) Legionella (Legionnaire’s disease)
Vibrio cholerae (Cholera) Delta Proteobacteria
-several soil bacteria
Epsilon Proteobacteria
-gastrointestinal infections
Classification of Prokaryotes
Chlamydias
-venereal disease
Classification of Prokaryotes
Chlamydias
-venereal disease
Spirochaetes
-disease organisms
Treponema pallidum - syphillus
Borrelia burgdorferi - Lyme disease
Classification of Prokaryotes
Gram positive Bacteria
-very diverse group
Some familiar ones:
Streptomyces - antibiotic production
Classification of Prokaryotes
Gram positive Bacteria
-very diverse group
Some familiar ones:
Streptomyces - antibiotic production
Bacillus anthrax - anthrax
Classification of Prokaryotes
Gram positive Bacteria
-very diverse group
Some familiar ones:
Streptomyces - antibiotic production
Bacillus anthrax - anthrax
Streptococcus - respiratory disease
Classification of Prokaryotes
Cyanobacteria - only prokaryotes with plant-like photosynthesis
Classification of Prokaryotes
Archaea - differ from bacteria in several ways but have no
peptidoglycan
Common in extreme conditions
1.  Thermophiles - live at extreme temperatures
(>100ºC)
Pyrolobus
-in deep sea vents
Classification of Prokaryotes
Archaea - differ from bacteria in several ways but have no
peptidoglycan
Common in extreme conditions
2. Halophiles - live at extreme salinities
Classification of Prokaryotes
Archaea - differ from bacteria in several ways but have no
peptidoglycan
Common in extreme conditions
3. Methanogens - use CO2 to oxidize H2 - release CH3
- “swamp gas”
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