Archaea

1. Archaea Extremophiles Evolutionarily Primitive Formerly known as Archaeabacteria

2. History Originally grouped with Bacteria Recognized in 1977 Carl Woese and George Fox 16S rRNA sequencing Greek archaea �ancient� Common ancestor thought to be a simplistic prokarya with poorly organized genetic material Thought to be involved in evolution of Eukarya-not accepted

3. Morphology Spherical, rod-shaped, spiral, lobed, filamentous, or rectangular

4. Morphology 0.1-15 microns Single circular chromosome Single cell membrane Flagella No organelles

5. Ecology Extremophiles (coined 1974) Thermophiles (up to 113C) Black smokers Geysers Psycrophiles Acidophiles and Alkaliphiles Halophiles Some combine extremes, ie Picrophilus (~60C and 0.5pH) Methanogens Often found in the guts of ruminants, termites and even humans Found in all known environments

6. Adaptations to Extremes In extreme pH must avoid hydrolysis of proteins-achieved by changing internal pH Anaerobes do not maintain stasis, while aerobes do Specific enzymes are active at optimal pH Structure of cell membrane stabilized in high temperature environments by: Allows for formation of carbon rings which increases stability Ether linkage is less reactive than ester linkage Tetraether molecules Can form monolayers (Sulfolobus and Thermoplasma)

7. Adaptations to Extremes Protection of genetic material High salt concentrations in cytoplasm DNA binding proteins similar to eukaryotic histones Share amino acid homology MC1-Methanosarcinaceae HMf-Methanobacteriales Organizes DNA in sturctures similar to chromatin Allows for positive supercoiling Eukarya have negative supercoiling (nucleosome) HTa-Thermoplasma HTa (like)-Sulfolobus

8. Evolution Primitive form Related to Eukarya tRNA Ribosomes TATA binding proteins and TFIIB (transcription) Similar initiation and elongation factors for translation Similarities to bacterial genetic material

9. Evolution