no spiral or mycelial shapes, unique features like RNA gene structure and methanogensis; have features in common with eukarya (geneencoding) and bacteria (genesformetabolism)
cell envelope (A)
slayer may be only layer outside the plasma membrane; some lack cell walls, generally no capsules or slime layers
cell membranes (A)
composed of unique lipids with isoprene units and ether linkages rather than ester; some are monolayer and ignicoccus is the only with outermembrane
cell walls (A)
lack peptidoglycan and most common wall is the Slayer; may have a protein sheath or pseudomurein; no translocation
ribosomes (A)
have additional 5.8s subunit of RNA; proteins are more similar to eukarya than bacteria
nucleoids (A)
usually not membranebound, 1 chromosome (evidence of polyploidy though), and proteins to aid in folding
pili (A)
not well understood, have a lumen like bacteria flagella and may be involved in adhesion
cannulae
tubelike structure on thermophilic Pyrodictium; unknown function, production in daughter cells?
hami
grappling hook-like structure, adhesion?
flagella (A)
thinner, not hollow, and growth occurs at base rather than at end; made of more than one type of protein
