Biodiversity - Prokaryotes: bacteria and archaea
are typically unicellular organisms that lack a membrane-enclosed
nucleus and membrane-enclosed organelles. From an evolutionary prospective, have
prokaryotes been successful?
A side note:
where do we put viruses
on the tree
The two major groups, bacteria and archaea, were placed in the Kingdom Monera.
Recent molecular analysis of
nucleotide sequences have shown that these two groups are distinctly
different and diverge from one another very early in the history of
life. Given the
phylogenetic tree shown below, why would some systematists insist that
these two groups of prokaryotes not be grouped under a single name
Numerous other differences
now support this division
Are all prokaryotes disease-causing?
The human intestine is
home to an estimated 500 to 1000 bacterial
species, many of which are symbiotes.
Bacteria make up a great proportion of biomass in the worlds oceans.
What would an alien viewing the Earth
without bias to size conclude about life on our planet?
most having cell wall composed of peptidogylcan (and surrounded by a sticky capsule)
The most common method of
locomotion in bacteria is the flagellum
allowing for taxis.
a flagellum work on your
Major groups of
diverse group capable
of numerous biochemical pathways
bacterium capable of converting
ammonium to nitrate
on animal cells,
causing blindness and
planktonic organism in
diverse group important
both ecologically and in human disease
bacteria used to produce
the antibiotic streptomycin
Many bacteria can be divided into
groups based on response to stain:
cell wall not composed of peptidogylcan
thermophiles, extreme halophiles, methanogens)
Methanogens use CO2 to oxidize H2
nucleotide sequences has also indicated that prokaryote diversity is
much greater and more complex than previous studies have
- While only 4,500
species have been fully characterized, some believe
that a handful of soil
could contain as many as 10,000 species. Why have so few bacterial species been
described so far?
gene transfer may be extensive and critical in understanding
relatedness among groups of single-celled organisms.
to the Tree of Life