chapter 4 - archaea

What are archaea

Unicellular prokaryotes, with no membrane bound organelles. And it’s at the kingdom domain level of organisms

How old are archaea

As old as bacteria(eubacteria) around 3.5-3.8billion years ago

4 Differences between archaea and eubacteria

• Archaea has ether linked membrane lipids instead of ester linked

• Archaea has isoprenoid based hydrocarbons instead of fatty acids in membrane lipids

• Archaea uses glycerol-1-phosphate in their membrane lipids while eubacteria uses glycerol-3-phosphate

• Archea uses enzyme glycerol-1-phosphate dehydrogenase while eubacteria sees glycerol-3-phosphate dehydrogenase

Why do archaea have ether linkages instead of ester

Ether linkages are stronger more resistant to environmental extremes such as pH fluctuations since they live in different extreme conditions

What type of membrane do archaea have

Monolayer, helps for stability against heat

What similarities do archaea and eubacteria share

No similarity, hypothesized that they evolved independently as cellular organis

What is this and where is it found

Ether linkage, in archaea membranes

What is this and where is it found

Ester linkage, in bacterial membranes

Archaea ribosomal RNA

Has 3 ribosomal rna and 1 additional (unlike 4 in eukaryotes)

• 16S small subunit

• 23S and 5S in large subunit

• Additional 5.8S

Archaea proteins in DNA replication

Transcription are more similar to eukaryotes than to eubacteria (most likely that eukaryotes are derived from archaea)

Archaea cell walls

• no peptidoglycan

• Some have psuedomurein - is a polymer of 2 sugars linked with amino acids (different from peptidoglycan sugar and L-amino acids)

Archaea cell wall structures

• They have different cell wall structures such as protein S-layers

2 major phylas for archaea

• crenarchaeota

• Euryachaeota

Other phyla of archaea (not major but important)

• Korarchaeota - only uncultured strains

• Nanoarchaeota - very small, may involve smallest prokaryote (nanoarcchaeum equitans)

Crenarchaeota characteristics

• Strains are thermophilic or hyperthemophilic

• Usually acidophiles

• Uncultivated representatives are widespread (polar and temperate marine water, soil and sediments)

What occurs in a compost

• bacteria decomposes the organic waste

• Steam comes out in the compact composts due to thermophiles (archaea) releasing heat as they do their job

Example of thermophilic

Thermoproteus grows between 70 and 97 degrees celcius,are deep branched group

• could be earliest form of cellular life

Example of hyperthemophilic

Pyrolobus grow up to 113 degree C

Why are archaea hyperthermophiles

They grow at high temps because they are found primarily under water

• BP increases when pressure increases which is why found deep in water

Example of acidophiles

Sulfolobus grows at pH 2

Characteristics of euyarchaeota

• widespread and diverse

• Include methanogens

• Extreme halophiles

• Thermophiles

Characteristics of methanogens

• All methanogens are archaea,never bacteria

• strict anaerobes

• Convert CO2 and H2, or C1 compounds such as formate and methanol to methane CH4

DPAAN superphylum characteristics

• previously unknown but widespread

• Generally obligate symbionts, some of the smallest organisims known (nanoarchaeum equitans)