Quiz two: Lecture three slides
DOMAIN EUKARYA
KINGDOM PROTISTA
PHYLUM DIPLOMONADA (diplomonads)
Slide 1: Giardia lamblia (a.k.a.) Giardia intestinalis: diplomonads have two equal sized nuclei and
multiple flagella—see the arrows. This organism causes what is sometimes called hikers diarrhea—
technically it is called giardiasis. Don’t drink water from streams, even if they look clean unless it has
been filtered or boiled. This slide shows the mature trophozoites, which reproduce asexually via
transverse fission within the intestines of their host. Some cells will form cysts, which will leave the
intestines within the host’s feces. Not all diplomonads are parasitic.
PHYLUM PARABASALIDA (trichomonads)
Slide 2: Trichonympha: species within this genus have mutualistic symbioses with insects such as
termites. This genus (along with other organisms) is an important component of the termite’s gut. These
organisms can hydrolyze cellulose, thus providing nutrients to the termite. The termite gut acts as a
home to these symbionts and provides a continual supply of cellulose—e.g., from your house! Notice the
cellulose fibers being digested in the bottom part of the cell.
EUGLENOZOA (Phylogenetic clade of protists that includes the phyla Euglenida and Kinetoplastida)
PHYLUM EUGLENIDA (euglenids)
Slide 3: Euglena: notice the eyespot (tip of the arrow) and long flagellum to the right. What is the
eyespot? Why is this organism green? At the base of the longest flagellum, there is a light detector.
The light detector is sensitive to light allowing the cell to move towards light (positive phototaxis),
presumably enhancing photosynthetic function. Most euglenids lack plastids and even those that have
plastids are mixotrophic—they can feed by photosynthesis, heterotrophy via phagocytosis or even
saprotrophy.
PHYLUM KINETOPLASTIDA (trypanosomes)
Slide 4: Trypanosoma gambiense: these flagellated protists cause African sleeping sickness. Notice the
flagella, the nucleus and the undulating membrane of these trpypanosome as it moves around red blood
cells. The vector of transmission for this species is the tsetse fly. Remember, they evade the host’s
immune system by antigenic variation.
AMOEBOZOA (Phylogenetic clade of protists that produce lobe-like pseudopodia; includes Myxomycota,
Acrasiomycota and Rhizopoda)
PHYLUM MYXOMYCOTA (acellular slime molds)
Slide 5: Physarum feeding plasmodium: this picture shows a mature, feeding plasmodium of an
acellular slime mold. This large multinucleate single cell would exhibit cytoplasmic streaming if viewed
alive. The plasmodium’s nuclei are diploid and karyokinesis (nuclear division) occurs
synchronously.
Slide 6: Physarum fruiting bodies (sporangia): the sporangia of this acellular slime mold looks like
poppy seeds. If resources become depleted or the environment dries out, the plasmodium will enter this
next phase of their life cycle. Inside the sporangium certain diploid nuclei will undergo meiosis, forming
haploid spores. The sporangia release the spores which are highly resistant to adverse conditions. The
spores disperse via air currents and may continue their life cycle if they reach more favorable, moist
conditions, forming new feeding plasmodium.
PHYLUM ACRASIOMYCOTA (cellular slime molds)
Slide 7: Dictyostelium: these organisms spend most of their lifecycle as single, amoeboid-like, haploid
cells. If the local environment begins to become unfavorable due to drought or a lack of food, the
amoebas will begin to congregate, forming a slug-like aggregate. This slide shows the slug-like aggregate
in the process of producing a fruiting body—a sporangium. Some of the cells of the fruiting body
become spores with tough protective protein coats, which are dispersed by the wind. If the spores land in
a favorable environment, haploid amoeba emerge and begin feeding.
PHYLUM RHIZOPODA (Gymnamoebas and Entamoebas)
Slide 8: Amoeba: notice the lobopodia—wide pseudopodia—which are blunt at the tip. Inside you can
see food vacuoles as well as the nucleus. What are the pseudopodia used for? Gymnamoebas are free
living heterotrophs, feeding on bacteria and other protists.
Slide 9: Entamoeba hystolytica: entamoebas are symbionts, often living commensally with their host. E.
hystolytica is a human parasite that causes amoebic dysentery, also known as traveler’s dysentery or
“Montezuma’s Revenge”. Cysts have four nuclei and leave the host via the feces. If ingested the cyst
undergoes cytokinesis to form four trophozoites.
RHIZARIA (Phylogenetic clade of protists that all produce thread-like pseudopodia)
PHYLUM ACTINOPODA (radiolarians)
Slide 10: Radiolarians (living): notice the axopods extending from the siliceous skeletons of these
organisms. The axopodia function in feeding via phagocytosis. Radiolarians are mostly planktonic in
warm ocean waters. In lab you saw the siliceous skeletal remains of these beautiful single celled
organisms.
PHYLUM FORAMINIFERA (forams)
Slide 11: Foram skeletons: notice the two calcareous tests (left) and the living foram with its
reticulopodia (right). The famous white cliffs of Dover are formed, in large part, from many trillions of
forams that lived and died over eons, resulting in the massive accumulation of their microscopic tests. All
are heterotrophic by means of phagocytosis via reticulopodia. In tropical water, planktonic forams often
have endosymiotic algae living in their tests.
ALVEOLATA (Phylogenetic clade of protists that includes the Ciliophora, Apicomlexa and Pyrrhophyta)
PHYLUM CILIOPHORA (ciliates)
Slide 12: Paramecium: be able to recognize the macronucleus, contractile vacuole and of course the
cilia that surround the cell. Paramecium is an extremely common ciliate found in fresh water ponds.
Slide 13: Stentor: notice the cilia at the anterior of the cell. These organisms use their cilia to create a
water current that is used to bring food to their cell membrane, which is then consumed via phagocytocis.
They can move, however, largely by contractions of their body with proteins called myonemes (proteins
similar to the myosin in your musceles). When disturbed they become ball shaped—remember this when
you are observing these organisms in lab.
PHYLUM APICOMPLEXA
Slide 14: Plasmodium: species within this genus cause malaria. The life cycle is very complicated. The
slide shows the organism (dark purple stained structures, note the arrows) as they look during the part of
their life cycle—called the merozoite—in which they invade red blood cells (round light-red structures).
PHYLUM PYRROPHYTA (dinoflagellates)
Slide 15: Peridinium: numbers 1-10 are various species of dinoflagellates in the genus Peridinium.
Number 11 is a picture of a species in the genus Ceratium. Notice the girdles created at the junction of
the cellulose plates of their cell wall. Certain species in this phylum will bloom in huge numbers when
exposed to eutrophic conditions. This can cause multiple problems. For one thing some of them
produce toxins. If “shellfish” feed on these organisms the shellfish can take up the poisons and should
not be eaten.
Slide 16: Red tide: A harmful algal bloom of the dinoflagellates Noctiluca scintillans, commonly known as
a red tide, which has bloomed due to eutrophic conditions.
Slide 17: Dinoflagellate bioluminescence: This picture shows bioluminescence in a population of the
dinoflagellate Pyrocystis fusiformis. The bioluminescence may be used as communication or defense.
Bioluminescence in living organisms comes from the energetically expensive oxidation of the molecule
luciferin by the enzyme luciferase.
PHYLUM CHOANOFLAGELLATA (choanoflagellates)
Slide 18: Choanoflagellate: molecular evidence indicates that the kingdom Animalia shares a common
ancestor with the choanoflagellates. Notice the collar and the flagellum. The organism creates water
current with the flagellum, using the collar as a net to capture food particles, which are consumed via
phagocytosis. Many species are colonial. When we study the sponges—the most plesiomorphic of the
animals, we will discuss the choanoflagellates again.
KINGDOM CHROMISTA
PHYLUM STRAMENOPILA
SUBPHYLUM OOMYCOTA (water molds)
Slide 19: Saprolegnia: notice the white hyphae growing all over this dead fish. Because of oomycetes
are saprophytic heterotrophes whose bodies are formed of hyphae, this phylum was once classified
within kingdom Fungi. However, unlike fungus, oomycetes do not use chitin in their cell walls—they use
cellulose—and they are diploid, fungi are haploid.
SUBPHYLUM PHAEOPHYTA (brown algae)
Slide 20: Fucus: this brown algae is found along the littoral zone of rocky, temperate shorelines. This
picture was taken at low tide; thus, Fucus must contend with huge environmental changes as it is
exposed to the atmosphere at least twice a day. Brown algae produce alginates in their cell wall that
form gels, which may protect them from dessication and the wear and tear of living in the littoral zone.
Notice the air sacs. These sacs allow the algae to float up towards the sun when immersed in water.
Slide 21: Laminaria: this genus is found just below the littoral zone of rocky, temperate shorelines. Be
able to identify the holdfast, stipe and blade of this algal thallus.
SUBPHYLUM BACILLARIOPHYTA (diatoms)
Slide 22: Diatoms: be sure to be able to distinguish the centric from the pennate frustules. What are
diatom frustules composed of?
Slide 23: Diatomaceous earth: this slide shows an outcropping of land composed of silica derived from
millions of years of deposits by diatoms. Obviously this rock layer was at one time part of an ancient
seafloor. We can see this rock formation now because it has been uplifted by tectonic activity e.g.,
earthquakes.