prokaryotes and the origin of eukaryotes

Chemoautotroph

carbon from inorganic carbon (pre photosynthesis) need iron sulfur and magnesium

Chemoheterotroph

carbon from breakdown of organic substances

earliest organisms on earth

prokaryotes - still dominate the biosphere today

how do prokaryotes grow

binary fission

Anabaena cylindrica

example of a multicellular prokaryote

what do some prokaryotes have

a flagella for locomotion

Gammaproteobacteria

Escherichia coli (gut, model organism)
Schigella (dysentery, shiga toxin)
Salmonella (food poisoning)
Pseudomonas: opportunistic pathogens

Other human pathogens:

Staphylococcus (skin → blood, organs)
Borrelia (Lyme disease)
Helicobacter (stomach infection)
Clostridium (Gram+, gut

Alphaproteobacteria:

widespread in oceans, freshwater, soil
free-living, symbionts, pathogens
gave rise to mitochondria

Cyanobacteria

oxygenic photosynthesis
some multicellular (Anabaena)
gave rise to chloroplasts

bacteria-

peptidoglycan in cell wall

• unbranched hydrocarbons

• one kind of RNA poly

• introns absent

• growth inhibited to some antibiotics

• histones absent

Atchaea

• no peptidoglycan in cell wall

• some membrane lipids

• several kinds of RNA poly

• introns present in some genes

• growth not inhibited by antibiotics

• histones present

• some species have ability to grow in 100 degree temp

endomembrane system evolved first from what

infoldings of the plasma membrane

what did platids evolve from

endosymbyotic cyanobacteria

what did secondary endosymbiosis do?

increased the diversity of algae

occured when a heterotrophic
protist engulfed an alga containing plastids

adding an extra membrane
chloroplasts of plants and green algae have twomembranes
plastids of others have three or four membranes. These include the plastids of Euglena (with three
membranes) that are most closely related to heterotrophic species.

Protists

Protists are eukaryotes and thus are much more complex
than the prokaryotes.

Mostly unicellular but also colonial (green algae,
choanoflagellates) and multicellular (kelps, red and green
algae, slime molds).

supergroup or clade Excavata

Mostly unicellular but also colonial (green algae,
choanoflagellates) and multicellular (kelps, red and green
algae, slime molds). So diverse that few general
characteristics can be cited without exceptions

Diplomonads

Multiple flagella, two separate nuclei, a simple cytoskeleton, and no plastids, reduced mitochrondria (mitosomes - no electron transport chain).
• One example is Giardia lamblia, a parasite that infects the human intestine.
– The most common method of acquiring Giardia is by drinking water contaminated with faeces containing the parasite in a dormant cyst stage

Parabasalids

No plastids, reduced mitochrondria-hydrogenosomes
• The best known species, Trichomonas vaginalis, a
vaginal parasite.
– It can infect the vaginal lining if the normal acidity
of the vagina is disturbed.
– The male urethra may also be infected, but without
symptoms.
– Sexual transmission
can spread the
infection.

Euglenozoans

flagella with a unique internal structure, can have plastids)
Photosynthetic, heterotrophic and mixotrophic
flagellates
• This group includes the kinetoplastids and
euglenids

Euglenids

Characterized by an anterior pocket from which one or two
flagella emerge.
Have a unique glucose polymer, paramylon, as a storage
molecule.
is chiefly autotrophic, other euglenids are mixotrophic or
heterotrophic. Plastids with three membranes (secondary
endosymbiosis)
Anterior pocket
Excavata

SAR-Stramenopiles

Flagellum with numerous fine hair like
projections, usually paired a smooth (non-
hairy) flagellum)

•Includes Diatoms
Golden Algae (Chrysophytes)
Brown Algae (Phaeophytes)

The plastids of these algae evolved
by secondary endosymbiosis. The
probable ancestor was a red alga.

SAR-Stramenopila: Diatoms (Bacillariophyta)

Unicellular. Unique glass-like walls composed of
hydrated silica embedded in an organic matrix.
• The wall is divided into two parts that overlap like
a shoe box and lid.
• Phytoplankton
• Diatomaceous earth

SAR-Stramenopila: Golden algae (Chrysophyta),

Named for the yellow and brown
carotene and xanthophyll pigments.
While most are unicellular, some are
colonial

SAR-Stramenopila: Brown algae (Phaeophyta)

The largest and most complex algae.
Multicellular, marine, Holdfast, stipe,
blades/lamina

SAR-Alveolata

Members of this clade have alveoli, small
membrane-bound cavities, under the cell surface.

Dinoflagellates (flagellated protists)
⚫ Apicomplexans (parasites)
⚫ Ciliates (ciliated protists, Paramecium).

SAR-Alveolata: Dinoflagellates

abundant components of phytoplankton some
heterotrophic or mixotrophic
• Two flagella sit in perpendicular grooves in the
“armour” (internal plates of cellulose) and
produce a spinning movement.

cause blooms can be bioluminescent

SAR-Alveolata: Apicomplexans

Parasites of animals and some cause serious human diseases.
– The parasites disseminate as tiny infectious cells (sporozoites) with a complex of organelles specialized for penetrating host cells at the apex of the sporozoite cell.
– Most have intricate life cycles with both sexual and asexual stages and often require two or more different host species for completion

SAR-Alveolata: Ciliates

a diverse protist group, is named for their use of cilia to move and feed.

Distinctive feature,
presence of two types
of nuclei: maco &
micro

SAR-Rhizarians:

Thread-like Pseudopodia for movement & feeding

include Foraminiferans and Radiolarians
Foraminiferan
Radiolarians: planktonic - silica
skeleton pseudopodia reinforced by
microtubules and radiate from the
body
Foraminiferans (forams): calcium
carbonate shell and ray like pseudopodia.
Often symbiotic algae living within the
test.
Radiolarian

Archaeplastida-Rhodophyta

(Red algae)

Unlike other eukaryotic algae, red algae
lack flagellated stages in their life cycle.
• The red colouration in many members due
to the accessory pigment phycoerythrin.
– Colouration varies among species and
depends on the depth which they
inhabit.
• The plastids of red algae evolved from
primary endosymbiosis of cyanobacteria
(same as in green plants and algae)

Archaeplastida-Chlorophyta

Green algae (chlorophytes and charophytes) are named for their
grass-green chloroplasts.
– Chloroplasts derived from cyanobacteria by primary
endosymbiosis.
– Charophytes are especially closely related to land plants

Unikota

includes animals, fungi, and protists
• Two clades: Amoebozoans and the Opisthokonts (animals, fungi,
and related protist

Unikonta-Amoebozoans

amoeba that have lobe- or
tube-shaped, rather than threadlike,
pseudopodia
• They include slime molds, tubulinids, and
entamoebas

Unikonta-Amoebozoans -Tubulinids

have lobe- or tube-shaped pseudopodia
• Heterotrophic and actively seek and consume
bacteria and other protists in soil or water
• E.g. Amoeba proteus

Unikonta-Amoebozoans - Entamoebas

Animal parasites
• Entamoeba histolytica causes amoebic dysentery: the third-
leading cause of human death due to eukaryotic parasites

Unikonta – Opisthokonts - Nucleariids

Amoebae feeding on bacteria & algae
• DNA sequence data, most closely related to
fungi

Unikonta – Opisthokonts - Choanoflagellates

Flagellated protists with collars around flagella
• DNA sequence data: most closely related to
animals