Advertisement Upgrade to remove ads


The domain that contains microbes with isoprenoid glycerol diether or diglycerol tetraether lipids in their membranes and archaeal rRNA (among many other features)


A transmembranous protein to which retinal is bound; it functions as a light-driven proton pump, allowing photophosphorylation without chlorophyll or bacteriochlorophyll; found in the purple membrane of halophilic archaea


A microorganism that requires high levels of sodium chloride for growth


A microorganism that grows optimally at temperatures greater than 85 degrees C


Strictly anaerobic archaea that derive energy by converting carbon dioxide, hydrogen gas, formate, acetate, and other compounds to either methane or methane and carbon dioxide


A peptidoglycan-like polymer found in some archaeal cell walls; it is distinguished from peptidoglycan by the presence of L-amino acids, N-acetyltalosaminuronic acid (NAT) and beta (1 to 3) glycosidic bonds

Sensory rhodopsin

A form of rhodopsin found in halobacteria and cyanobacteria that senses the spectral quality of light


Microorganism that grow best at high temperatures and low pH


Occupy many different ecological niches and have a variety of metabolic patterns; includes methanogens, extreme halophiles, sulfate reducers, and many extreme thermophiles with sulfur-dependent metabolism


Cyclopentane ring-containing lipids unique to Crenarchaeota; used as a biomarker for the presence of crenarchaeotes in natural environments such as marine plankton


21st amino acid incorporated into two specific regions of archaeal mRNA; synthesized from serine; found in all domains of life


22nd amino acid present only in several methanogenic archaea and a single bacterium; derived from lysine

Pseudomurein, chondroitin sulfate-like polysaccharides, or protein walls

What do archaeal cell walls have instead of peptidoglycan?

Have ether instead of ester linkages, long tetraethers, and pentacyclic rings

How do the membrane lipids of archaea differ from those of other organisms?

Increased core hydrophobicity, packing density, and hydrogen bonds

How are proteins made more rigid in thermophiles?

Increased supercoiling

How is DNA protected from denaturation in thermophiles?

Irregularly lobed, spherical cells

What shape are cells in the genus Sulfolobus?


What type of "-philes" are members of the genus Sulfolobus?

Long, thin, bent or branched rods

What shape are cells in the genus Thermoproteus?


What is the cell wall of members of the genus Thermoproteus composed of?

Hot springs

Where are members of the genus Thermoproteus found?


Which group(s) of Archaea use bacteriorhodopsin in their purple membrane?

Outward proton transport

What is the function of bacteriorhodopsin?

Inward chloride ion transport

What is the function of halorhodopsin?

Purple membrane

Modified region of the plasma membrane containing bacteriorhodopsin molecules


Rhodopsin found in α- and β-proteobacteria and the Bacteroidetes

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording