27 Prokaryotes Abbreviated 20120130
Transcript of 27 Prokaryotes Abbreviated 20120130
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Bacteria on the point of a pin
Chapter 27:Bacteria and Archaea
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26.21. The three domains of life. Branch lengths areproportional to the amount of genetic change in each lineage.Lineages with multi-cellular organisms shown in red
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Harmful Haemophilus influenza, the bacteria that causes pneumonia
(shown on human nose cells)
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27.21. Lyme disease, a bacterial disease transmitted by ticks.([)
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Bacillus anthracis. Gram stain. The cells have characteristic squared ends.The endospores are ellipsoidal shaped and located centrally in thesporangium. The spores are highly refractile to light and resistant to staining.
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Without prokaryotesecosystems wouldcollapse!
54.11
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55.4 An overview of energy and nutrientdynamics in an ecosystem.
Decomposition connects all
trophic levels in an ecosystem
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If all the bacteria on Earth suddenlydisappeared, which of the following would
be the most likely direct result?
A. Human populations would thrive in the absenceof disease.
B. The Earth's total photosynthesis woulddecline markedly.
C. The number of organisms on Earth woulddecrease by 10 to 20 percent.
D. There would be little change in the Earth'secosystems.
E. Recycling of nutrients would becatastrophically reduced.
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27.16.
A simplified
phylogeny of
prokaryotes.
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Table 27.2.
A comparison of the three
domains of life
Antibiotic target
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27.17 Some Archaea: Thermo-acidophile (heat-acid loving) prokaryotes
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Some Archaea: Hot springs, home of thermophiles ()
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Methanogens () in Peat
and the gut of cows
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Some Archaea:
Extreme halophiles
()
Halobacterium:
32%
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Common Features of the Domain Bacteria
May be classified according to their shape (just like Archaea)
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (a combination ofsugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction
Diversity of nutritional modes
Often live in close association (symbiosis) with eukaryotes
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27.2 The most common shapes of prokaryotes
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Common Features of the DomainBacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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27.6. Prokaryotic flagellum with the basal apparatus as a motor.
Taxis/chemotaxis
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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27.7 Specialized membranes of prokaryotes
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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Figure 27.3 Gram-positive and gram-negative bacteria
Gram staining: Apply crystal violet dye to bacterial smear, treat with
iodine, rinse with alcohol and counterstain with safranin.
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Gram-positive and gram-negative bacteria
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Staphylococcus aureusStreptococcus pneumoniae
Actinomycete
Gram Positive
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Escherichia coliNeisseria gonorrhoeae
Yersinia pestis
Gram Negative
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27.4. Capsule
The cell wall of may prokaryotes
is covered with a sticky layer ofpolysaccharides or proteins.
27.5. Fimbriae
Hair-like protein appendages
that allow a prokaryote to
attach itself to their substrate
or to each other.
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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27.8. A prokaryotic chromosome and plasmids.
A single ring ofDNA surrounding a ruptured E. colicell.
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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Asexualreproduction:
Fission(see also Fig 12.11)
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Genetic recombination in prokaryotes
No meiosis and fertilization, but
Transformation:
Uptake and incorporation of foreign DNA from the
environment
Conjugation:
Direct transfer of genes from one prokaryote to
another
Transduction:
Transfer of genes between prokaryotes by viruses
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27.12. Prokaryotic conjugation.
Donor cell transfersDNA to recipient.
j Flagella, fimbriae, pilus
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27.13. Conjugation: Direct transfer of genes from one prokaryote to another
(have only been studied in Bacteria)
The F factor is responsible for producing the mating bridge. It can either
exist as a plasmid (a small circularDNA molecule with accessory genes)
or as a segment ofDNA within the bacterial chromosome.
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27.11. Transduction:
Transfer of genes between
prokaryotes by viruses.
Phages may carry pieces of
bacterial chromosome from
one bacterium (donor) to a
recipient bacterium.
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Endospores
27.9. Bacillus anthracis endospore (TEM)
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes Taxis/chemotaxis
Often live in close association (symbiosis) witheukaryotes
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Prokaryotes can evolve rapidly because of theirshort generation times
Cooper and Lenski,Michigan State University E coli, 12 populations, 20,000 generations (8 years) of evolution
Fig. 27.10 Can prokaryotes evolve rapidly in response to environmental change?
CONCLUSION
Asexual populations ofE. colicontinued to accumulate beneficial mutations for 20,000
generations, allowing rapid evolution of improved performance in theirnew environment.
Low-glucose
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Table 27.1 MajorNutritionalModes
- H2S,S-, Fe-comp.,NH3
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Figure 27.14. One of the most independent organisms on earth:
Cyanobacteria (in this case Anabaena) or blue-green algae
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Common Features of the Domain Bacteria
May be classified according to their shape
Many are motile using flagella
No membrane-enclosed organelles (prokaryotic!)
Peculiar cell wall containing peptidoglycan (acombination of sugars and polypeptides)
Smaller and simpler genome (than eukaryotes)
A sexual or sexual reproduction Diversity of nutritional modes
Often live in close association (symbiosis) witheukaryotes
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Symbiotic relationships
Mutualism bothsymbiotic organismsbenefit
Commensalism onebenefits, the otheris neutral
Parasitism onebenefits at theexpense of the other
27.20. Bacterial headlights. Glowing oval below the
eye of the flashlight fish contains bioluminescent
bacteria that receive nutrients from the fish. The fishuses the light to attract prey and signal potential mates
SEM ofEscherichia coli, very common in the lower
intestine of warm-blooded animals where it produces a
vitamin and protect against pathogenic bacteria.
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37.9. The role of bacteria in the nitrogen cycle
Nitrogen fixing bacteria in root nodules
(mutualism) and in cyanobacteria (heterocysts)
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Putting prokaryotes to work in sewage treatment facilities
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Figure 27.17 (a) Bioremediation of an oil spill, (b) bacteria
synthesizing biodegradable plastics, and (c) bacteria used to
produce ethanol from plants.
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AlexanderFleming18811955
1928(Penicillin)1938
:
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1945
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, , , ,
, :
14%53.7%
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In which of the following ways are prokaryotes
more successful on Earth than humans?
A. Prokaryotes often parasitize humans in many ways.
B. Prokaryotes are much more numerous than
humans.
C. Prokaryotes occupy more diverse habitats than
humans.
D. Prokaryotes have survived on Earth for billions ofyears longer than humans have.
E. All of the above are true.