Exam 16: Diversity of Archaea

Ignicoccus has several unique structural features that have lead scientists to propose that it may be the modern descendent of the ancestral cell type that gave rise to the origin of eukaryotic cells.What are the unique features of Ignicoccus and why do they support this hypothesis?

When retinal in bacteriorhodopsin becomes excited,it directly catalyzes the formation of ATP.

Halobacterium salinarum and certain other extreme halophiles carry out light-driven synthesis of ATP under what condition?

Crenarchaeotes whose optimal growth temperature is over 80°C are called

Which of the following is TRUE about the crenarchael genera Sulfolobus?

Which microbial grouping is the major oxygenic phototroph in most salt lakes?

Hot sulfur-rich environments associated with terrestrial sulfur-rich springs are called

Cellular integrity and cell wall stabilization of the Halobacterium are aided by

Thermostable proteins tend to have additional features that improve thermostability.Which of the following is NOT one of these features?

Compatible solutes counteract the tendency of a cell to become

Halophilic Archaea are the only inhabitants of highly saline environments.

The ribosomes of Halobacterium require high ________ levels for stability and activity.

Which archaeal phylum contains primarily extreme halophiles and methanogens?

What is the minimum concentration of sodium chloride that an extreme halophile requires for growth?

Proteins known as ________ function to refold partially denatured proteins.

The topoisomerase ________ introduces positive supercoils in DNA,which stabilizes DNA and prevents the DNA helix from denaturing at high temperatures.

The factor that MOST affects the thermostability of a protein is its

Some crenarchaeotes have growth optima above the boiling point of water (at atmospheric pressure).

Which statement is TRUE of methanogenic and extremely halophilic Archaea?

Many halophiles require a high ionic environment for survival.