C15-C21 Flashcards
(33 cards)
Anoxygenic photosynthesis is
present in six bacterial phyla:
Proteobacteria, Chlorobi, Chloroflexi,
Firmicutes, Acidobacteria, and Gemmatimonadetes
Oxygenic photosynthesis, by contrast, is known only within the
Cyanobacteria
Cyanobacteria key genera:
Prochlorococcus, Crocosphaera, Synechococcus,
Trichodesmium, Oscillatoria, Anabaena
Cyanobacteria morphological groups: unicellular, dividing by binary fission
Chroococcales
Cyanobacteria morphological groups: unicellular, dividing by multiple fission
(colonial)
Pleurocapsales
Cyanobacteria morphological groups: filamentous nonheterocystous forms
Oscillatoriales
Cyanobacteria morphological groups: filamentous,
divide along a single axis, and are capable of cellular differentiation
Nostocales
Cyanobacteria morphological groups: morphologically similar
to Nostocales except that cells divide in multiple planes, forming
branching filaments
Stigonematales
a lineage of unique unicellular Cyanobacteria once thought to be
distinct but now classified within the Chroococcales.
prochlorophytes
cyanobacteria morphology; short, motile filaments that
break off from longer filaments to facilitate dispersal in times of
stress.
hormogonia
cyanobacteria morphology; resting structures which protect the organism during periods of darkness, desiccation, or cold/
akinetes
cyanobacteria morphology; copolymer of aspartic acid and arginine and is a nitrogen storage product; when nitrogen in the environment becomes
deficient, it is broken down and used as a cellular nitrogen source.
cyanophycin
Purple sulfur bacteria key genera;
Chromatium, Thermochromatium, Ectothiorhodospira
anoxygenic phototrophs that use hydrogen sulfide (H2S) as an electron donor for photosynthesis
purple sulfur bacteria
purple non-sulfur bacteria key genera;
Rhodospirillum, Rhodoferax, Rhodopseudomonas,
Rhodobacter
the most metabolically versatile of all microbes; not always
purple; these organisms synthesize an array of carotenoids
Purple nonsulfur bacteria
One interesting characteristic shared by all species of purple nonsulfur bacteria
presence of a “photosynthetic gene
cluster” (PGC); set of several connected operons
whose genes encode the necessary proteins to carry out anoxygenic
photosynthesis
Aerobic Anoxygenic Phototrophs key genera
Roseobacter, Erythrobacter
obligatory aerobic heterotrophs that use light as a supplemental source of energy to support growth; strict heterotrophs and employ anoxygenic photosynthesis only
under oxic conditions as a supplemental source of energy; unable to fix CO2 and thus rely on organic
forms of carbon as their carbon source.
aerobic anoxygenic phototrophs
Green Sulfur Bacteria key genera
Chlorobium, Chlorobaculum, Prosthecochloris,
“Chlorochromatium”
coherent group of
anoxygenic phototrophs that forms the phylum Chlorobi; have little metabolic versatility, and they are typically
nonmotile and strictly anaerobic anoxygenic phototrophic bacteria.
The group is also morphologically restricted and includes primarily
short to long rods
Green sulfur bacteria
green sulfur bacteria; a marine species whose cells form extensions of the cytoplasm
and cell wall called prosthecae
Prosthecochloris
Green Nonsulfur Bacteria; key genera
Chloroflexus, Heliothrix, Roseiflexus
also called filamentous anoxygenic phototrophs, are anoxygenic phototrophs of the phylum Chloroflexi; All cultured representatives are filamentous bacteria that are capable of gliding motility.
green nonsulfur bacteria