BMSC210 CH4.3 Flashcards
What phylum do the majority of gram-negative bacteria belong to?
Proteobacteria
What are gram-negative bacteria that do not belong to the phylum Proteobacteria called?
Nonproteobacteria
What are three classes of gram-negative nonproteobacteria?
Spirochetes, CFB group, Planctomycetes
How are spirochetes characterized?
Long, spiral-shaped bodies
Why is it difficult to examine spirochetes under a conventional brightfield microscope?
They are very thin
What type of microscopy is typically used to examine spirochetes?
Darkfield fluorescent microscopy
Why are spirochetes difficult or impossible to culture?
They are highly motile
What is the axial filament of a spirochete?
Similar to a flagellum, but wraps around the cell and runs inside the cell body of a spirochete in the periplasmic space between the outer membrane and the plasma membrane.
Are there spirochetes that are human pathogens?
Yes
What are the gram-negative nonproteobacteria of the CFB group called?
Cytophaga, Fusobacterium, and Bacteroides
What are fusobacteria?
Bacteria that inhabit the human mouth - They may cause severe infectious diseases.
What type of environments are CFB bacteria adapted to?
Anaerobic environments
What is the main function of CFB bacteria in ruminant animals?
To process cellulose in the rumen
What are Cytophaga?
Motile aquatic bacteria that glide.
Which is the largest genus of the CFB group?
Bacteroides
Where are Bacteroides commonly found?
Human large intestine
What percentage do Bacteroides make up in the entire gut microbiome?
About 30%
What do bacteria like Bacteroides benefit from in the gut?
Nutrients in the gut
How do humans benefit from Bacteroides in the gut?
Prevention of pathogen colonization
What happens to the gut when populations of Bacteroides are reduced?
Increased susceptibility to pathogenic bacteria and fungi
Which species of Bacteroides is pathogenic?
B. melaninogenicus
Where are Planctomycetes found?
Aquatic environments
How do Planctomycetes reproduce?
By budding
What are swarmer cells?
Motile cells not attached to a surface
What allows sessile cells to attach to surfaces in the water?
a holdfast
What is the primary source of energy for phototrophic bacteria?
Sunlight
How do phototrophic bacteria synthesize ATP?
They use solar energy through photosynthesis.
What is the difference between oxygenic and anoxygenic photosynthesis?
Oxygenic photosynthesis produces oxygen, while anoxygenic photosynthesis does not.
Which type of photosynthesis do the majority of phototrophic bacteria perform?
Anoxygenic photosynthesis.
What pigments do purple or green bacteria use for photosynthesis?
Bacteriochlorophylls.
What are some of the accessory pigments found in bacteria?
Carotenoids
What colors can the bacteria with carotenoids appear?
Orange, red, purple, green
How are bacteria with carotenoids classified?
Sulphur and nonsulphur
What type of photosynthesis do sulphur bacteria perform?
Anoxygenic photosynthesis
What do sulphur bacteria use as electron donors?
Sulphites
What is released by sulphur bacteria during photosynthesis?
Free elemental sulphur
What pigments give purple sulphur bacteria their purple color?
Bacteriochlorophylls and carotenoids
What is the genus of bacteria that are purple?
Chromatium
Where do sulphur Gammaproteobacteria live?
Water
What is the only source of carbon for sulphur Gammaproteobacteria?
Carbon dioxide
What greenhouse gas is produced by Chlorobium?
Methane
What is the implication of Chlorobium in climate change?
It produces methane, a greenhouse gas
What are the special vesicle-like organelles called where bacteriochlorophyll is stored?
Chlorosomes
What is the potential value of green nonsulphur bacteria in the field of biotechnology?
Ability to produce biological plastic and hydrogen fuel
How are green nonsulphur bacteria different from green sulphur bacteria?
Use substrates other than sulphides for oxidation
What is the proposed role of cyanobacteria in the Earth’s atmosphere change?
Change from anoxic to oxygen-rich environment
Where can cyanobacteria thrive?
Many habitats, including marine and freshwater environments, soil, and even rocks
What range of temperatures can cyanobacteria tolerate?
Wide range, even extreme temperatures of the Antarctic
How do cyanobacteria live?
Unicellular or in colonies, filamentous, forming sheaths or biofilms
What is a notable ability of many cyanobacteria?
Nitrogen fixation
What is the primary photosynthetic pigment in Cyanobacteria?
Chlorophyll a
What process gave rise to the eukaryotic chloroplast?
Endosymbiosis with an ancestor of cyanobacteria
