MicrobiologyLesson 3 of 3 in the course Prokaryotic Diversity

Archaeal Cell Features, Extremophiles, and Disease Associations

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Archaea are unicellular organisms that form a domain of prokaryotic life distinct from Bacteria. This lesson introduces the structural features that distinguish archaea and explores Crenarchaeota, a diverse group frequently associated with aquatic and extreme environments.

Archaea are unicellular, but their cell structures and molecular biology differ from those of bacteria. Their membranes contain ether linkages joining branched isoprene chains. Bacterial membranes, by contrast, generally use ester linkages and unbranched fatty acids. Some archaeal membranes can form a monolayer rather than the more typical bilayer, an adaptation that can help maintain stability in demanding conditions.

All flashcards

How do archaeal membrane lipids differ from typical bacterial membrane lipids?
Archaeal membranes have ether linkages and branched isoprene chains; typical bacterial membranes have ester linkages and unbranched fatty acids.
What are the five major archaeal phyla commonly recognized?
Crenarchaeota, Euryarchaeota, Korarchaeota, Nanoarchaeota, and Thaumarchaeota.
How do methanogens commonly produce methane?
They produce methane by reducing carbon dioxide with hydrogen.
How do some Halobacteria use bacteriorhodopsin?
They use the protein in a form of photosynthesis; it also contributes to their purple color.
What does finding an archaeon in a diseased site establish?
It establishes an association, not necessarily that the archaeon caused the disease.

Quiz questions

  1. Which type of linkage characterizes archaeal membrane lipids?Answer: Ether linkages connect branched isoprene chains.
  2. Which statement describes archaeal cell walls?Answer: They lack bacterial peptidoglycan; some contain distinct pseudopeptidoglycan.
  3. Which archaeal group is thought to be among the most abundant microorganisms in the oceans?Answer: Crenarchaeota
  4. What is methanogenesis?Answer: Methane production by archaea, commonly through reducing carbon dioxide with hydrogen.
  5. What can be concluded from finding *Methanobrevibacter oralis* in people with periodontal disease?Answer: The finding shows an association but does not establish that the archaeon caused the disease.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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