Download Prokaryotes

Prokaryotes
Domain Bacteria
Domain Archaebacteria
Domain
Bacteria
AP Biology
Domain
Archaea
Domain
Eukarya
2007-2008
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)
Domain
Bacteria
Domain
Archaea
Common ancestor
Domain
Eukarya
Bacteria live EVERYWHERE!
 Bacteria live in all ecosystems
on plants & animals
 in plants & animals
 in the soil
 in depths of the oceans
Microbes always
 in extreme cold
find a way to
make a living!
 in extreme hot
 in extreme salt
 on the living
 on the dead

Bacterial diversity
rods and spheres and spirals
eukaryote cell
Prokaryote Structure
 Unicellular

bacilli, cocci, spirilli
 Size

1/10 size of eukaryote cell
 1 micron (1um)
 Internal structure:
prokaryote
cell
Prokaryote vs. Eukaryote Chromosome
Prokaryote
Eukaryote
double helix
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
conjugation
 direct transfer of DNA
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
mitochondria
Variations in Cell Interior
cyanobacterium
(photosythetic) bacterium
chloroplast
aerobic bacterium
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
Gram-positive bacteria
peptide side
chains
cell wall
peptidoglycan
plasma membrane
That’s
important for
your doctor
to know!
protein
peptidoglycan = polysaccharides + amino acid chains
lipopolysaccharides = lipids + polysaccharides
Gram-negative bacteria
cell wall
outer membrane of
lipopolysaccharides
outer
membrane
peptidoglycan
plasma
membrane
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
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AP Biology
2007-2008
Gram
positive
Are these bacteria Gram + or Gram –?
Gram
negative