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Domain Eukarya- The Eukaryotes `
Domain Eukarya- The Eukaryotes
`
Most taxonomist now recognize the domain as the largest
taxon. The three taxa at the domain level are the Bacteria,
Archae, and Eukarya. All eukaryotes are in the domain
Eukarya. Within those domains are super groups. The king-
doms are found within the super groups. Of the five king-
doms three have survived-Animalia, Plantae, and Fungi. The
Monerean and Protista kingdoms are no longer recognized.
The major difference between prokaryotic and eukaryotic
cells, is the existence of membrane bound organelles. These
organelles include the nucleus, E.R., lysosome, Golgi
apparatus, mitochondrion and plastid. The advantage of
having compartmentalization allows for specialization of
tasks and greater efficiency.
The evolution of the organelles involves two different
processes- involution of cell membranes to form the
cytomembrane (endomembrane) system and endosymbiosis.
Shown is the possible outline of sequence of events that led
to the cytomembrane system which led to the develop-ment
of the nucleus, E.R., Golgi apparatus, lysosome, vacoules
and vesicles.
The origination of the mitochondrion is thought to have
come about by a prokaryotic cell engulfing another aerobic
heterotrophic prokaryote. This cell took up residence and
eventually became the mitochondrion. Evidence for this
includes that the mitochondrion like prokaryotic cells have
circular, nonhistone DNA. The mitochondrion has
prokaryotic-like ribosomes and does proteins synthesis
like a prokaryotic cell. The
mitochondrion replicates
doing binary fission like a
prokaryotic cell.
The origination of plastids (chloroplasts, chromoplasts and
leukoplasts) thought to have come about by a prokaryotic
cell engulfing another photosynthetic, aerobic prokaryote.
This cell took up residence and eventually became the
chlroroplast. Evidence for this includes that the plastids
like prokaryotic cells have
circular, non-histone DNA.
The plastid has prokaryotic-
like ribosomes and does
proteins synthesis like a
prokaryotic cell. The plastid
replicates doing binary
fission like a prokaryotic cell.
In the course of evolution this
has happened many times.
The algae that were involved in a secondary endosymbiosis
have 3-4 membranes on their chloroplasts.
All protists have a nucleus and are therefore eukaryotic.
Protists are either plant-like, animal-like or fungus-like.
1)PROTOZOANS Animal-like protists
* unicellular * live in H2O * heterotrophs
* microscopic * 4 phyla classified by locomotion (how they move)
Protist Group
Amoebas:
shapeless
protists
Flagellates Ciliates Sporozoans:
parasitic
Phylum Rhizopoda Zoomastigina Ciliophora
8,000 kinds
Sporozoa
Type of
Locomotion
Pseudopodia =
cytoplasm-
containing
extensions;
change shape
Flagella whip
from side to
side
Cilia covers body No movement
immobile
Example Amoebas
(freshwater
and salt
water)
Trypanosome (get
by fly bite)
One that lives in
termite guts
Paramecium
*Contractile
vacuole to get
rid of excess
water
Plasmodium
All are parasites.
Type of
Reproduction
Asexual
reproduction
by binary
fission
Binary fission Binary fission &
Conjugation
Spores =
reproductive
cell that forms
without
fertilization
Diseases? African sleeping
sickness
malaria
Notes 3
The Prostista Kingdom no longer exists. Protists though
are considered to be unicellular (or multicellular without
differentiation). In other words any eukaryote not
considered to be a plant, animal or fungus is a protist.
Remember, protists, animals, fungi, and plants are all in the
same domain, Eukarya.
There are five recog-
nized super groups
in the domain
Eukarya
1. Excavata
2. Chromalveolata
3. Rhizaria
4. Archaeplastida
(plant kingdom
found in this group)
5. Unikonta
(Animal and Fungi
Kingdom found in
this group)
All the tan boxes
represent groups
that used to be in the
Protista Kingdom.
The super group Excavata (relationship in the Eukarya is not
clear)
a. Grove on one side of the cell body
b. Diplomonads and Parabasalids have reduced
mitochondria
c. Euglenozoans have flagella with unique spiral rod
i. Kinetoplastids-have large mitochondrion with large
mass of DNA-feed on prokaryotes
ii. Euglenid-some mixotrophs in
light do photosynthesis
in the dark become
heterotrophic. Have protein
pellicle under the cell membrane.
Giradia intestinalis
(shown) can cause
intestinal distress and
diarrhea.
Trichomonas vaginalis is a
sexually transmitted
parasite that can infect
both males and females
causing tissue damage.
Has the ability to change
surface proteins to evade
recognition by the immune
system. (tricky little
suckers!)
The tsetse fly – sleeping sickness
vector
The super group- Chromalveolata
I. Alvelolates-have membrane bags under cell membrane
A. Dinoflagellates-cellulose plates with perpendicular
grooves with flagella. Cause of red tide. Some autotrophs,
heterotrophs and mixotrophs.
B. Apicomplexan-parasites (Plasmodium) causes malaria.
Complex life cycle
C. Ciliates-Covered with cilia (Paramecium caudatum) has
large and small nuclei
II. Stramenopiles-covered with numerous fine “hairy”flagella
which is paired with regular shorter flagellum
Dinoflagellates: The Spinning Ones
Spin around using two flagella
Responsible for Red Tides
Create toxins that can kill animals and sometimes people
The life cycle of Plasmodium, the cause of malaria
Dinoflagellate causes red tide
Cilliates to include stentor and
parmecium
Sexual reproduction
Asexual reproduction
Binary
fission
II. Stramenopiles-covered with numerous fine “hairy”flagella
which is paired with regular shorter flagellum. Stores
energy in form of laminarin (polysaccharide) and oil.
A. Diatoms-cell walls of silicon dioxide (glass) that overlap
Petri dish. Very strong . Over 100,000 species.
B. Golden algae have yellow and brown caroteinoids. Most
unicellular, some mixotrophs.
C. Brown algae-Most complex of all the algae. Somewhat
like plants (analogous structures) Kelp beds Used for
food in some countries.
DIATOMS
The brown
algae exhibits
the life cycle
like plants-
alternation of
generations.
D. Oomycetes (water molds) was once classified as fungus
because of hyphae (long strings of cells) but case of
convergent evolution. Has cell walls of cellulose not chitin.
No longer has plastid and are decomposers. Cause of potato
blite in 19th century. Decomposer.
` The super group- Rhizaria
Many members have long, stringy pseudopods (fake extension)
A. Forams (foraminerferans) have shells made of calcium
carbonate. Pseudopods extend through the pores.
B. Radolarians internal skeletons of silica with pseudopods
extending out.
Globerigerina-radolarian
Radolarian
The super group- Archaeplastida
Contains red algae, green algae and Plant Kingdom
A. Red algae-contain photosynthetic accessory pigment,
chlorophyll A and phycoerythrin. Makes the algae appear
red-green to red depending on the amount. Phycoerythrin
absorbs blue and green light so red algae can survive in
deeper water that blue and green light penetrates. Mostly
multicellular and has alternation of generation life cycle
with no flagellated gametes.
B. Green algae-contain chlorophyll A and B like higher plants
1. Chlorophytes unicellular, colonial and multicellular
species. Reproduction includes alternation of generations.
Example of red algae to the left
and green algae above
Chlamydomonas are actually unicellular and flagellated.
A Volvox is a hollow boll composed of hundreds of flagellated cells in a single layer.
Life cycle of chlamydonas-single celled green algae
2. Charophytes rosette shaped cellulose synthesizing
complexes, and other characteristics in common with
higher plants. Closest relative to land plants.
Super group Unikonta-two major clades Amoebozoans and
Opisthokonts. Include slime molds, amoebas, fungi and
animals.
I. Amoebozoans-
A. Gymnamoebas- amoebas with club-like pseudopods.
Heterotrophs consuming prokaryotes and other protists
B. Entamoebas- parasitic amoebas. Entaboeba histoytica
causes dysentery.
C. Slime molds- Two types Plasmodial slime molds form
acelluar masses where as cellular slime molds form
cellular plasmodial masses. Can live as individual cells
II. Opisthokonts-Includes nucleariids, fungi, choanoflagellates
and animal.
A. Nucleariids are amoeba-like protists and more closely
related to fungi than other protists
B. Kingdom Fungi that are absorptive heterotrophs.
Characterized by columns of cells called hyphae. Most
are multicellular.
C. Choanoflagellates are flagellated protists that will form
colonies. Individuals look much like sponge cells.
D. Kingdom Animalia are multicellular ingestive
heterotrophic organisms.
