2007-2008 AP Biology
Prokaryotes
Domain Bacteria
Domain Archaebacteria
DomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
What characteristics make Archaea more like eukaryotes than prokaryotes?
No peptidoglycan in cell wall
More than 1 RNA polymerase
Some introns Met is 1st amino acid in
protein synthesis Ribosomes more like
eukarytoes (Streptomycin does not kill archaea)
DomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
Bacteria live EVERYWHERE! Bacteria live in all ecosystems
on plants & animals in plants & animals in the soil in depths of the oceans in extreme cold in extreme hot in extreme salt on the living on the dead
Microbes alwaysfind a way to
make a living!
Bacterial diversityrods and spheres and spirals
Prokaryote Structure Unicellular
bacilli, cocci, spirilli
Size 1/10 size of eukaryote cell
1 micron (1um)
Internal structure:
prokaryotecell
eukaryote cell
Prokaryote vs. Eukaryote Chromosome
double helix
Prokaryote
Eukaryote
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 you have billions of E. coli in your gut!
lots of mutation potential!
Genetic recombination bacteria swap genes
small supplemental circles of DNA
direct transfer of DNAconjugation
Metabolic Relation to Oxygen
How are bacteria categorized by the effect that oxygen has on growth?
Obligate aerobes Facultative anaerobes Obligate anaerobes What role do prokaryotes play in
nitrogen cycling? Only way that nitrogen gas can be
incorporated into organic molecules
Variations in Cell Interior
internal membranesfor photosynthesislike a chloroplast(thylakoids)
internal membranesfor photosynthesislike a chloroplast(thylakoids)
internal membranes
for respiration
like a mitochondrion
(cristae)
internal membranes
for respiration
like a mitochondrion
(cristae)
aerobic bacterium
mitochondria
cyanobacterium(photosythetic) bacterium
chloroplast
Origins of Metabolic Diversity Heterotrophs most likely came before
photoautotrophs (parsimony) Glycolysis was probably the first metabolic
pathway Natural selection favored autotrophs as
heterotrophs depleted food supply Cyanobacteria introduce chl a and oxygen
gas.
Cell Wall
What are the functions of the cell wall in prokaryotes?
Maintain cell shape Protection Prevent bursting in hypotonic environment Made of peptidoglycan Why is some food preserved by salting it? Hypertonic environment plasmolyzes
bacterial cells
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
That’simportant foryour doctorto know!
Prokaryotic metabolism How do bacteria acquire their energy &
nutrients? photoautotrophs
photosynthetic bacteria chemoautotrophs
oxidize inorganic compounds nitrogen, sulfur, hydrogen…
heterotrophs live on plant & animal matter decomposers & pathogens
Disease Disease –
exotoxins release poisons such as botulism and cholera
Endotoxins seen in outer membrane of gram neg. bacteria (Salmonella)
What are Koch’s postulates and why are they important?
Koch’s postulates used to isolate pathogen causing disease
Bacteria as pathogens Disease-causing microbes
plant diseases wilts, fruit rot, blights
animal diseases tooth decay, ulcers anthrax, botulism plague, leprosy, “flesh-eating” disease STDs: gonorrhea, chlamydia typhoid, cholera TB, pneumonia lyme disease
Bacteria as beneficial (& necessary) Life on Earth is dependent on bacteria
recycling of nutrients from dead to living only organisms that can fix N 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
Germinating akinetes
2007-2008 AP Biology
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Are these bacteria Gram + or Gram –?
Gram positive
Gram negative