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Domain EukaryaThe Protists
Most taxonomists now recognize the domain as the largest
taxon. The three taxa at the domain level are the Bacteria,
Archaea, and Eukarya. All eukaryotes are in the domain
Eukarya. Within those domains are super groups. The kingdoms are found within the super groups. Of the five kingdoms three are still used-Animalia, Plantae, and Fungi. The
Moneran 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 sequence of events that led to the
cytomembrane system which led to the development of the
nucleus, E.R., Golgi apparatus, lysosome, vacoules and
vesicles.
Which of the following is not
considered to be a domain?
A) Eukarya
B) Archaea
C) Protista
D) Bacteria
ANS:
C
There are three domains (super-kingdoms)
based on the sequencing of the ribsomal
RNA. These include the Eukarya (all
eukaryotic cells), Archaea (prokaryotic
cells more closely related to eukaryotic
cells), and Bacteria (prokaryotic cells not in
the domain Archaea). The kingdoms that no
longer exists are the Monera kingdom and
the Protista kingdom
The origination of the mitochondrion is thought to have come
about by endosymbiosis, meaning 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
protein synthesis like a prokaryotic cell.
The mitochondrion also
replicates by undergoing
binary fission like a
prokaryotic cell.
Which of the following is not
considered to be part of the
endomembrane and cytomembrane
system?
A) Golgi apparatus
B) flagellum
C) nucleus
D) lysosome
ANS:
B
The endomembrane system includes all of
the following-nucleus, Golgi apparatus,
lysosome, E.R., vacuoles, and vesicles.
These are membranes that are connected
to one another or originate from one
another. The flagellum is made from
microtubule proteins.
The origination of plastids (chloroplasts, chromoplasts and
leukoplasts) is also thought to have come about by
endosymbiosis when a prokaryotic cell engulfing another
photosynthetic, aerobic prokaryote. This cell took up
residence and eventually became the chlroroplast.
Evidence for this includes that plastids,
like prokaryotic cells, have
circular, non-histone DNA. A
plastid has prokaryotic-like
ribosomes and does protein
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.
Which of the following is NOT evidence
that supports the endosymbiosis hypothesis
for the origin of mitochondria?
A) Mitochondria have a membrane like a
prokaryotic cell.
B) Mitochondria have non-histone, circular
DNA like a prokaryotic cell.
C) Mitochondria have smaller prokaryotic
like ribosomes.
D) Mitochondria replicate like a prokaryotic
cell
ANS:
A
Both eukaryotic cells, the mitochondria,
and the prokaryotic cell have a membrane,
so this NOT a piece of evidence to support
the endosymbiosis hypothesis, the other
three statements are true. They do
support the endosymbiosis hypothesis.
The algae that were involved in a secondary endosymbiosis
have 3-4 membranes on their chloroplasts.
The Prostista Kingdom is no longer
used by taxonomists. The term Protist
refers to eukaryotic organisms that are
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 recognized 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.
Which considered to be the correct
sequence from largest grouping to
smaller grouping?
A) super group -> domain -> kingdom
B) kingdom -> domain -> super group
C) domain -> super group -> kingdom
D) domain -> kingdom -> super group
ANS: C
The correct sequence is
domain -> super group -> kingdom
The super group Excavata (relationship in the Eukarya is not
clear)
a. Oral Groove 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- 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!)
Some taxonomists argue that Diplomonads and
Parabasalids are closely related to prokaryotes.
The best reasoning for this is
A) like prokaryotic cells, they do not have nucleus.
B) they contain smaller ribosomes like prokaryotic
cells.
C) like prokaryotic cells, they have circular DNA.
D) they contain reduced, nonfunctioning
mitochondrion.
ANS:
D
Diplomonads and Parabasalids contain
reduced, nonfunctioning mitochondrion.
Diplomonads and Parabasalids have linear
DNA, normal eukaryotic ribosomes and do
have nucleus.
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
The life cycle of Plasmodium, the cause of malaria
Ciliates to include stentor and
paramecium
Dinoflagellate causes red tide
Which of the following is true?
A) Malaria is a rare disease
B) Malaria is treated by common
antibiotics
C) Malaria uses leeches as vector to
infect human
D) Malaria is caused by the protist
Plasmodium
ANS: D
Malaria is caused by a protistPlasmodium. It uses a mosquito as a
vector to infect humans. It is a
common disease in the tropics,
infecting 300,000,000 and killing
approximately 2,000,000 people
annually. Scientists are trying to find
an antibiotic that will be treatment
but so far nothing has been developed.