26 terms

Bacteria and Archaea

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Domain archaea
extremophiles (halophiles, thermophiles); some live in more moderate environments such as methanogens
Extremophile
an organism that lives in an environment whose conditions are so extreme that few other species can survive there; these include extreme halophiles and extreme thermophiles
Extreme halophile
an organism that lives in a highly saline environment, such as the great salt lake or the deExtreme thermophilead sea
Extreme thermophile
an organism that thrives in hot environments (often 60-80 degrees celsius or hotter)
Methanogen
an organism that obtains energy by using carbon dioxide to oxidize hydrogen, producing methane as a waste product; all known are in teh domain archaea
Prokaryotes diversity of shape
cocci, bacilli, spirilli
Bacilli
rod-shaped prokaryotes
Cocci
spherical prokaryotes
Spirilli
spiral prokaryotes
Prokaryotes diversity of form
mostly unicellular, but also colonial and filamentous
Peptidoglycan
a type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides
Gram stain
a staining method that distinguishes between two different inds of bacterial cell walls (peptidoglycan)
Gram-positive
describing the group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative bacteria; these bacteria are usually less toxic than gram-negative bacteria; appear purple
Gram-negative
describing the group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan thatn the cell wall of gram-positive bacteria; these bacteria are often more toxic than the gram-positive bacteria; cell appears pink or red
Prokaryotes diversity of extensions
some have flagella for movement, others have pili for attachment
Prokaryotes diversity of nutrition
photoautotroph, chemoautotroph, photoheterotroph, and chemoheterotroph
Chemoautotroph
an organism that needs only carbon dioxide as a carbon source but obtains energy by oxidizing inorganic substances
Chemoheterotroph
an organism that must consume organic molecules for both energy and carbon
Photoautotroph
an organism that harnesses light energy to drive teh synthesis of organic compounds from carbon dioxide
Photoheterotroph
an organisms that uses light to generate ATP but must obtain carbon in organic form
Prokaryotes metabolic diversity
prokaryotes "invented" photosynthesis (nonoxygen generating, oxygen generating (cyanobacteria = important for evolution of chloroplasts)); bacteria "invented aerobic respiration (eg. proteobacteria (important for the evolution of mitochondria))
Ecological importance of bacteria
decomposers; nutrients recycling (biogeochemical cycles); symibosis (mutualism, commensalism, parasitism); pathogens (causing diseases, releasing harmful toxins)
Mutualism
a symbiotic relationship in which both of the participants benefit
Commensalism
a symbiotic relationship in which one organism benefits but the other is neither helped nor harmed
Parasitism
a symbiotic relationship in which on erganism, the parasite, beneftis at the expense of another, the host, by living either within or on the host
Oxygen revolution
(2.2 - 2.7mya, near archaean/proterozoic boundary) cyanobacteria and O2 generating photosynthesis; rising O2 levels = major environmental changes (ozone layer (UV shield), toxic to many species, new selective pressures ( led to origin of eukaryotes around 2.1bya)