Biol 165: Diversity of Life
• Non-nucleate organisms
• Consists of Domain Bacteria and Archaea
• They DO NOT have the following:
o nucleus, nucleolus, ER, mitochondria, and chloroplasts
• Their flagella are not homologous with that of eukaryotes
o lack 9+2 composition
• They are often MUCH smaller than eukaryotic organisms
• The ribosomes of prokaryotes and eukaryotes are
homologous, revealing a distant ancestor.
• Traditional: used to be included in Kingdom of Monera
• There are 100s of unknown and undescribed prokaryotes.
• Their classification is based on 16S RNA sequences, and are
• Modern: Monera divided into 2 Domains
o Domain Bacteria
many are disease causing
some are photosynthetic (autotroph)
others are heterotrophs
Divided into 16 Phyla, or 14 Kingdoms, depending
on referred text.
o Domain Archaea
most are anaerobes (do not need oxygen).
NONE are known to cause diseases
They occupy extreme habitats (extremophiles)
and are chemotrophs.
Divided into 2 Phyla or 3 Kingdoms:
Crenarchaeota, Euryachaeota, and Korarchaeota.
• Scientists are still unsure if Archaea and Bacteria share a
common ancestor, or Archaea and Eukarya do.
Shapes of Bacteria
Cell Division Biol 165: Diversity of Life
• occurs by simple Binary Fission
• duplicated chromosomes attach to the cell membrane on
• new cell wall forms in middle and pinched apart to for two
• some bacteria form a bud that is pinched off instead of
division in the middle, dividing the cell equally.
• Chromosomes are coiled, and consist of Double-stranded DNA
o 18-50% of a bacteria’s DNA is not indigenous.
o bacteria exchange DNA through transfer of sequences
from plamids – lateral gene transfer.
o their 16S RNA sequence is not likely to be transferred –
protected and necessary for cell to live.
o Conjugation: the transfer of genes from one
prokaryote cell to another.
o Plasmids: extrachromosomal genetic material not
essential for growth. Often act as vectors. These get
passed between bacteria during conjugation.
• not homologous with the undulipodia(flagella) of eukaryotes
• do not have 9+2 microtubule configuration, and are
composed of different proteins
• are used for locomotion, and perform a propeller-like action.
Gram Staining of Bacteria
• Gram+ bacteria have a cell wall consisting of mostly exposed
o They stain PURPLE
• Gram- bacteria have a protective outer membrane, and the
peptitoglycan lies behind that wall.
o They stain RED
• As such, the Gram- bacteria are harder to treat with
antibiotics because they have a more resilient outer
membrane that does not permit easy access of the
• This is often the first test performed in labs to determine the
species of bacterial disease and the appropriate mode of
• Biol 165: Diversity of Life
• have a the most complex life cycle of all prokaryotes
• known as “slime-molds”, and produce “fruiting-bodies”.
• resemble fungi, but are not.
• ALL LIFE STAGES ARE 1n!
• are colonial, not multicellular.
Genus: Streptiomyces and Actinomyces
• Are a large group of filiamentous, and Gram+ bacteria.
• They form fungal-like masses with elaborat