Ch 11: Prokaryotes: Domains, Bacteria, and Archaea Flashcards
What phylum contains mostly chemoheterotrophic bacteria and is the largest taxonomic group of bacteria? Gram-positive or Gram-negative?
- Proteobacteria
- Gram-negative
What are the subclasses of proteobacteria?
- Alpha-
- Beta-
- Gamma-
- Delta-
- Epsilon-
Identify the genus:
- Phylum: Alphaproteobacteria
- One of the most abundant microbes on Earth (accounts for 25% of ocean bacteria)
- Only one species (ubique) of this genus
- 0.3 μm diameter
- Simplest autonomously replicating cells (1,354 genes)
Pelagibacter (pel-aj’ē-bak-ter)
True or false. Pelagibacter contains no duplicate gene copies, viral genes, introns, or junk DNA.
True
How does Pelagibacter get its energy?
- Respiring organic carbon
- Using a light-driven proton pump (not photosynthesis)
Identify the genus
- Phylum: Alphaproteobacteria
- Found in low-nutrient aquatic environments (i.e. lakes)
- Produce prominent prostheca and has a dimorphic cycle
- Replicate by budding at hyphal tips
Hyphomicrobium
Identify the genus
- Phylum: Alphaproteobacteria
- Found in low-nutrient aquatic environments (i.e. lakes)
- Produce prominent prostheca and has a dimorphic cycle
- Produce stalks for anchoring to surfaces and increasing SA/Vol ratios
- Replicate by binary fission
Caulobacter
Identify the genus:
- Phylum: Alphaproteobacteria
- Nitrogen-fixing
- Enter the roots of leguminous plants and form nodules
- Endosymbiotic and cannot fix nitrogen independently from host plant
Rhizobium
Identify the genus:
- Phylum: Alphaproteobacteria
- Nitrogen-fixing
- Free-living on plant root surfaces commonly found on tropical grasses and sugarcane
- Uses nutrients excreted by plants and fixes nitrogen in return
Azospirillum
Identify the genus
- Phylum: Alphaproteobacteria
- Plant pathogen; invade plant cells but do not induce nodules or fix nitrogen
- Species tumefaciens induces crown gall disease in plants
Agrobacterium
Identify the genus:
- Phylum: Betaproteobacteria
- Nitrogen-fixing: NH4+ → NO2-
- Chemoautotroph (oxidize nitrogen for energy and fix CO2)
Nitrosomonas
Identify the genus
- Phylum: Alphaproteobacteria
- Part of the nitrogen cycle: NO2- → NO3-
- Chemoautogrph (oxidize nitrogen for energy and fix CO2)
Nitrobacter
What is a facultative intracellular parasite?
Microbe that can reproduce outside or inside of the cells
Identify the species
- Phylum: Alphaproteobacteria
- Facultative intracellular parasite
- 40% of cats carry it in their mouths or under their claws; acquired from infected fleas
- Bacillus inhabits cat’s RBCs
- Primary mode of transmission to humans is infected flea feces
- “Cat-scratch fever”
Bartonella henselae
Identify the genus:
- Phylum: Alphaproteobacteria
- Facultative intracellular parasite
- Different species infect cattle, swine, goats, sheep, dogs, and humans
- Spreads to humans by contact with animals or ingestion of undercooked meat or unpasteurized dairy products
- Can survive in phagosomes of macrophages by blocking lysosomal fusion
- Causes Brucellosis
Brucella
What is an obligate intracellular parasite?
Microbe that requires a host to reproduce
Identify the genus
- Phylum: alphaproteobacteria
- Obligate intracellular parasite
- Pleomorphic (rods or coccobacilli)
- Transmitted to humans by insect or tick bites
- Prefers to infect endothelial cells lining blood vessels
- Cause several diseases known as the spotted fever group
Rickettsia
What species of Rickettsia causes epidemic typhus? How is it transmitted?
- R. prowazekii
- Transmitted through lice
What species of Rickettsia causes endemic murine typhus? How is it transmitted?
- R. typhi
- Transmitted through rat fleas
What species of Rickettsia causes rocky mountain spotted fever? How is it transmitted?
- R. rickettsii
- Transmitted through ticks
Identify the genus:
- Phylum: Alphaproteobacteria
- Obligate intracellular parasites
- Rickettsia-like bacteria
- Transmitted by ticks to humans and cause ehrlichiosis
- Survive phagosomes after phagocytosis in macrophages
Ehrlichia
Identify the genus:
- Phylum: Alphaproteobacteria
- Endosymbiont; lives in cells of insects and other invertebrates
- Not a human pathogen, but the most common infectious bacterial genus on Earth (infects over 1 million species)
- 20-75% of all insects are infected
- Complex interactions with hose; interfere with reproduction and egg development
Wolbachia
True or false. All betaproteobacteria are anaerobic
False. They are all aerobic
Identify the genus
- Phylum: Betaproteobacteria
- Relatively large cell bodies that twist like a spiral
- Habitat: freshwater (with one species exception)
- Motile due to bipolar tufts of flagella
Spirillum