Lecture 18 Flashcards
1
Q
- How many phyla of Bacteria have been identified?
- What are these phylogentic groupings based on?
A
- Over 80 phyla have been identified.
- Based on 16S (SSU) rRNA gene sequence analysis.
2
Q
- Describe Proteobacteria
- Describe Bacteroidetes
- Describe Actinobacteria
- Describe Tenericutes
- Describe Firmicutes
- Describe Cyanobacteria
- Describe Chlamydiae
A
- Gram-negative; diverse metabolically, ecologically, morphologically; includes many plant and animal pathogens and symbionts.
- Gram-negative, non-sporulating; includes Bacteroides (major members of the human intestine microbial community).
- high GC Gram-positive bacteria, includes filamentous soil bacteria (Actinomycetes, antibiotic producers).
- Lack cell wall, includes Mycoplasma (human pathogen).
- low GC Gram-positive bacteria, includes lactic acid bacteria.
- large group of oxygenic phototrophs, origin of chloroplast of Eukarya.
- small Gram-negative bacteria, obligate intracellular parasites of Eukarya.
3
Q
- What are the six classes of Proteobacteria?
- What is unique about this group of bacteria?
- How do they contribute to major biological and human importance?
- What else are they important to?
- What are they the origin of?
A
- Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, Zetaproteobacteria.
- It is the largest and phenotypically most diverse bacterial group.
- Play key roles in the carbon, sulfur and nitrogen cycles on Earth.
- Also have medical, veterinary, industrial and agricultural importance.
- Orgin of Mitochondrion
4
Q
- What is the morphology of Proteobacteria?
- Do they express motility?
- What is their life style?
- How do they obtain their energy?
- What is their relationship to oxygen?
- What is the point of the figure attached?
A
- rods, cocci, curved, spiral, ring-shaped, appendaged, filamentous, sheathed forms.
- many are motile by means of polar or peritrichous flagella, some use gliding motility.
- mostly free-living; some are symbiotic with certain plants or animals, a few are pathogens and some are obligate intracellular parasites of humans or other mammals, some form complex multicellular fruiting bodies.
- They are chemoorganotrophs, chemolithotrophs, and phototrophs.
- Strictly aerobic, strictly anaerobic, facultative aerobes and microaerophiles.
- No phylogentic clusters of major metabolim, they are all mixed together.
5
Q
- What class of Proteobacteria does Caulobacter crescentus belong to?
- Why are they a model of cell differentation?
- What is their lifestyle?
- What kind of habitats do they live in?
- How do they attach to surfaces?
A
- Alphaproteobacteria
- They have unequal binary fission, division of labor (stalked cell and swarmer cell). Differentiates a polarly flagellated swarmer cell.
- Aquatic, heterotrophic, aerobic.
- Live in low nutrient habitats (oligotroph)
- Attaches to surfaces with a stalk.
6
Q
- Describe the stalk elongation and DNA synthesis process in Caulobacter crescentus.
A
- Process:
- Swamer cell disperses to a new location.
- Holdfast forms. flagellum is lost, and cell attaches to a surface (at about the 15 minute mark)
- Stalk (contains cytoplasm) elongates and DNA synthesis begins.
- Synthesis of flagellin (flagellar protein) begins.
- Cross-band formation occurs and cell divides.
- Stalked cell (mother cell) can give rise to many swarmer cells, on after another
7
Q
- What class of Proteobacteria does Ralstonia eutropha belong to?
- Describe Ralstonia eutropha:
- Is it Gram-pos or Gram-neg?
- What type of metabolism does it have?
- What does hydrogen oxidation generate? What enzyme carries out this reaction?
A
- Betaproteobacteria
- Describe:
- Gram-negative
- Facultative chemolithotrophic (can grow chemoorganotrophically) as a chemolithotroph, oxidizes hydrogen aerobically using oxygen, microaerophilically, and fixes CO2 for carbon.
- Generates proton motive force for ATP synthesis. Hydrogenase (oxygen sensitive)
8
Q
- How many hydrogenases does Ralstonia eutropha have?
- What are they used for?
A
- Ralstonia eutropha has two hydrogenases.
- One is cytoplasmic - reduces NAD+ for use in CO2 fixation. The other is in the membrane - passes electrons to an electron transport chain for synthesis of ATP.
9
Q
- What class of Proteobacteria does Photobacterium, Aliivibrio and Vibrio belong to?
- Describe Photobacterium mandapamensis.
A
- Belongs to Gammaproterbacteria
- Gram negative, heterotrophic (chemoorganotrophic), facultatively aerobic marine (moderate halophile).
- Luminous (bioluminecent) (30 species of bacteria make light; in genera Aliivibrio, Photobacterium, Vibrio, and Shewanella, which are marine, and Photorhabdus, which are terrestrial).
- Photobacterium mandapamensis is symbiotic with coral reef fish (bioluminescent symbiosis).
- Only six species of luminous bacteria form bioluminescent symbiosis.
10
Q
- What class of Proteobacteria does Myxococcus belong to?
- Describe Myxococcus xanthus:
- What is it metabolism?
- What type of motility does it express?
- Where are they found?
- How do they obtain their nutrients?
- What do they do under starvation conditions?
- What does nutrient depletion trigger?
- What does this process consist of?
A
- Belong to Deltaproteobacteria
- Myxococcus xanthus
- Gram-negative, strictly aerobic, chemoorganotrophic.
- Express gliding motility, uses slime for motility. slime = myxo
- Found in soil and on decaying plant materials.
- Obtain their nutrients primarily by lysing other bacteria (extracellular enzyems).
- Under starvation conditions, the cells aggregate and form multicellular, macroscopic fruiting bodies.
- Triggers fruiting body formation.
- Cells aggregate together (extracellular signals). Form a mound, some cells differentiate to form a stalk. Others form myxospores to protect against dessication, UV, and heat.
11
Q
- Describe the Life Cycle of Myxococcus:
A
- Life Cycle of Myxococcus:
- independent and group behavior as vegetative cells - movement and feeding.
- nutrient depletion triggers release of aggregation signal. Aggregation = swarm together
- differentiation - some cells form stalk, some cells become myxospores.
- myxospores - survive lack of nutrients, desiccation.
- Can be spread to new locations and begin growing vegetatively when they encounter sufficient moisture and food.
12
Q
- What class of Proteobacteria does Helicobacter belong to?
- Describe Helicobacter pylori:
- How does it obtain its energy?
- What does it colonize?
- What do they cause?
- Who won the 2005 Nobel Prize? Why did they win?
- What do genetic studies of humans reveal?
A
- Epsilonproteobacteria
- Helicobacter pylori:
- Gram-negative, heterotrophic, microaerophilic (use low O2 and high CO2 for culturing)
- Colonizes the mucosal lining of the stomach and upper intestinal tract.
- Causes gastric ulcers.
- Barry Marshall and Robin Warren. Helicobacter pylori has a role in gastritis and peptic ulcer disease.
- Revealed that different groups of humans have different strains of H. pylori; human migrations can be tracked by genetic typing of this bacterium, which has been associated with humans at least since humans first migrated out of Africa.