Glossary

ARCHAEA

March, 18th 2021

Features

1) In the late 1970s they discovered a different type of prokaryotic cell.

2) The walls of these cells lacked the peptidoglycan common in most bacteria.

3) Differences in rRNA sequences.

4) Generally live in extreme conditions.

5) Prokaryotic organisms.

6) Biochemistry and rRNA markers distinct from eubacteria and more similar to eukaryotes

7) The cell membrane has lipids with ether ester bonds.

8) They are prokaryotes.

9) Asexual reproduction by spores

10) No core

11) They lack organelles that enable them to carry out a specific activity.

12) Some withstand high temperatures.

13) Synthesize sulfur and other chemical substances.

Genoma

1) Circular chromosome, translation and transcription similar to Eukarya.

Cell structure

1) No nucleus or cellular organelles

Reproduction

1) Binary fission

2) Horizontal transfer

Metabolism

1) Organotroph.

2) Lithotroph.

3) Chemosynthetic.

4) Photosynthetic.

Habitat

1) Acidophilus:

2) Alcholophic:

3) Barophilic or piezophilic:

4) Endolith:

5) Halófilo:

6) Hypetermophilic:

7) Metatolerant:

8) Oligotroph:

9) Osmophil:

10) Psychrophil:

11) Radio-resistant:

12) Thermophile:

13) Thermophile:

IMPORTANT PHYLUM

Crenarchaeota: is a class of Archaea that is extremely diverse, containing genera and species that differ vastly in their morphology and requirements for growth. All Crenarchaeota are aquatic organisms, and they are thought to be the most abundant microorganisms in the oceans. Most, but not all, Crenarchaeota are hyperthermophiles; some of them (notably, the genus Pyrolobus) are able to grow at temperatures up to 113 °C.

Euryarchaeota: includes several distinct classes. Species in the classes Methanobacteria, Methanococci, and Methanomicrobia represent Archaea that can be generally described as methanogens. Methanogens are unique in that they can reduce carbon dioxide in the presence of hydrogen, producing methane. They can live in the most extreme environments and can reproduce at temperatures varying from below freezing to boiling. Methanogens have been found in hot springs as well as deep under ice in Greenland. Some scientists have even hypothesized that methanogens may inhabit the planet Mars because the mixture of gases produced by methanogens resembles the makeup of the Martian atmosphere.

Korarchaeota: 1) Can be grown in the laboratory. 2) Hyperthermophilic. 3) Their closeness at the base of the genetic tree shows their antiquity.

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