archaebacteria & bacteria classification old 5 kingdom system monera protists plants fungi...
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Archaebacteria&
Bacteria
Classification• Old 5 Kingdom system
• Monera• Protists• Plants• Fungi• Animals
• New 3 Domain system• Bacteria
• Archaebacteria
• Eukaryotes– Protists
– Plants
– Fungi
– Animals
ProkaryoteEukaryote
Prokaryotes
Domain Bacteria
Domain ArchaebacteriaDomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
Prokaryote cell COMPOSITION!
Macromolecule Primary Subunits Where found in cell
Proteins amino acids Flagella, pili, cell walls, cytoplasmic membranes, ribosomes, cytoplasm
Polysaccharides sugars (carbohydrates) capsules, inclusions (storage), cell walls
Phospholipids fatty acids membranes
Nucleic Acids nucleotides DNA: nucleoid (chromosome), plasmids
(DNA/RNA) rRNA: ribosomes; mRNA, tRNA: cytoplasm
Prokaryote cell Structure• Unicellular
– bacilli, cocci, spirilli
• Size– 1/10 size of eukaryote cell
• 1 micron (1um)
• Internal structure– no internal compartments
• no membrane-bound organelles• only ribosomes
– circular, naked DNA• not wrapped around proteins
Staining Characteristics
Gram + Gram –
Stains according to the thickness of the peptidoglycan layer!
Prokaryote Cell Wall Structure
peptide sidechains
cell wallpeptidoglycan
plasma membrane
protein
Gram-positive bacteria
Gram-negative bacteria
peptidoglycan
plasmamembrane
outermembrane
outer membrane of lipopolysaccharides
cell wall
peptidoglycan = polysaccharides + amino acid chainslipopolysaccharides = lipids + polysaccharides
Prokaryotic metabolism• How do bacteria acquire their energy & nutrients?
– autotrophs• acquire carbon from inorganic sources(CO2)
– phototrophs• photosynthetic bacteria
– chemotrophs• oxidize inorganic compounds/chemicals
– nitrogen, sulfur, hydrogen…
– heterotrophs• live on plant & animal matter• decomposers & pathogens
Bacteria as beneficial (& necessary)
• Life on Earth is dependent on bacteria– decomposers
• recycling of nutrients from dead to living– nitrogen fixation
• only organisms that can fix N2 from atmosphere– needed for synthesis of proteins & nucleic acids– plant root nodules– help in digestion (E. coli)
• digest cellulose for herbivores– cellulase enzyme
• produce vitamins K & B12 for humans– produce foods & medicines
• from yogurt to insulin
Genetic variation in bacteria• Mutations
– bacteria can reproduce every 20 minutes• binary fission
– error rate in copying DNA• 1 in every 200 bacteria has a mutation
• Genetic recombination– bacteria swap genes
• plasmids– small supplemental
circles of DNA
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