Q57 - Protein Adaptations of Halophilic Archaea to High Intracellular Salt

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Microorganisms that live at high salt concentration (above 2M of NaCl) are exposed to media with low water activity, and must have mechanisms to avoid water loss by osmosis. Analyses of intracellular ionic concentration of Halobacteriales living in salt lakes show that these microorganisms maintain extremely high salt (KCl) concentration inside their cells. The presence of high intracellular salt concentration requires special adaptations of the proteins and other macromolecules of the cells.

Using the information and data, determine which of the statements are true or which are false.

A. Most intracellular proteins of Halobacteriales contain a large excess of charged amino acids on their outer surface.

B. Halobacteriales spend a lot of ATPs to maintain osmotic pressure.

C. Most intracellular enzymes of Halobacteriales lose their catalytic activity when suspended in solutions containing less than 1 M NaCl.

D. In Halobacteriales, amino acids can be imported through Na+/amino acids antiporters.

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Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)