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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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