Module 3 Flashcards
Archaea
features archaea have in common with bacteria
molecules in the cytoplasm (mRNA, tRNA, ribosomes, and DNA)
can have inclusion bodies - gas vacuoles, vesicles, etc
most have a single circular chromosome
lack a membrane-bound nucleus
features archaea have in common with eukaryotes
have a polymerase in common, they’re homologues
have histone proteins
how do histone proteins differ in archaea vs eukaryotes
eukaryotic histone proteins form an octamer, archaea: tetramer
definition: nucleosome
DNA wrapped around histone proteins
what keeps nucleosomes together
histone proteins are positively charged
DNA is negatively charged
what is typically in the cell envelope of archaea
cell membrane
cell wall
no outer membrane
what are some differences with archaea plasma membrane
the polar head groups are glycerol 1-phosphate instead of glycerol 3-phosphate (mirrored)
there is a phytanyl chain instead of fatty acid tails
what is the structure of a phytanyl chain
4 repeated isoprene units (a 5-carbon compound)
what is the benefit of the phytanyl chain being linked by an ether linkage as opposed to an ester one
beneficial for cells inhabiting high temperatures
brings additional stability
definition: biphytanyl chain
two sets of phytanyl chains covalently linked in the middle
stronger than those is a bilayer
when will the proportion of biphytanyl chains increase
in higher temperatures
what is a tetraether layer
another name for the monolayer that archaea will form
what are some differences in the archaea cell wall
has beta-1,3-glycosidic linkages
has NATs instead of NAMs
there are no D-amino acids present
describe: S-layer
surface layer/slime layer
protects against predation and viruses
mediates adhesion to existent biofilm
describe: cannulae
they are tubes made up of sugars and proteins
form complex networks
function is not well understood
compare archaea flagella to bacterial flagella
assembled from the base outwards
simpler
more solid
more narrow
made up of more than one type of protein
what are the 2 major phyla of archaea
Euryarchaeota
Crenarchaeota
what is the main feature of Crenarchaeota
they are extremophiles
temperature, pressure, acid, etc.
having increased proportions of arginines and tyrosines is a feature of which archaea
thermophiles (and other extremophiles)
what is a way that thermophiles increase their stability in terms of metabolism
they possess reverse DNA gyrase
increases the extent of DNA supercoiling
what is the main feature of Thaumarchaeota
they are intermediate/lower temp loving (mesophilic)
many are found in the ocean
where in the ocean are there more archaea than bacteria
lower down
what is the main feature of Euryarchaeota
contains all known methanogens
what are some features of halophiles
require very high salt concentrations
have high concentrations of potassium to combat high salinity
