Detailed Discussion on Parasitism and Protozoan

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This ppt provides us with information about parasitism. Parasitism is the relationship between two living species in which one living species is benefited at the expense of the other.
2. Protozoa are a diverse
assemblage with mixed
 a. They lack a cell wall.
 b. They have at least
one motile stage in the
life cycle.
 c. Most ingest their
3.  Biological Contributions
 1. Protozoa have intracellular
specialization or organization of
organelles in cells.
 2. Cells may have distinct functions;
some colonial protozoa have separate
somatic and reproductive zooids.
 3. Asexual reproduction occurs by
mitotic division.
 4. Some have true sexual
reproduction with zygote formation.
4.  5. Responses to stimuli represent
the simplest reflexes and inborn
behaviors known.
 6. Shelled protozoa have the
simplest exoskeletons.
 7. Basic enzymes systems support
all types of nutrition: autotrophic,
saprozoic and holozoic.
 8. Many have developed means of
5.  General Features
 1. A protozoan is a complete organisms
in which all life activities are carried on
within the limits of a single plasma
 2. Phylogenetic studies show that
protozoa do not form a monophyletic
 3. Over 64,000 species are named; half
are fossils.
 4. Although they are unicellular
organisms, protozoan cell organelles are
highly specialized.
 5. They are ecological diverse, widely
dispersed, but many are limited to narrow
environmental ranges.
6.  6. They can be fantastically numerous,
forming gigantic ocean soil deposits.
 7. About 10,000 are symbiotic in or on
animals or plants; some are human
disease agents.
 8. Some are colonial with multicellular
stages but have noncolonial forms.
 9. Protozoa have only one non-
reproductive cell type and lack
embryonic development; embryonic
development is one of the criteria for
7.  Characteristics of Protozoan
 1. They are unicellular with some
colonial and multicellular stages.
 2. Most are microscopic.
 3. All symmetries are present
within members of the group.
 4. No germ layers are present.
 5. No organs or tissues are
formed, but specialized organelles
serve many of these functions.
8.  6. They include free-living,
mutualistic, commensal and
parasitic forms.
 7. They move by pseudopodia,
flagella, cilia and they can direct
cell movements.
 8. Most are naked, but some have
a simple endoskeleton or
9. 9. All types of nutrition are
present: autotrophic,
heterotrophic and saprozoic.
10. They can be aquatic or
11. Reproduction is asexual by
fission, budding or cysts; or
sexual by conjugation or syngamy
of gametes.
10. Classification: Follows Hausmann and
Hulsmann (1996) and represents a major
departure from the Eleventh Edition:
Phylum Chlorophyta
Phylum Retortamonada
Class Diplomonadea
Order Diplomonadida
Phylum Axostylata
Class Parabasalea
Order Trichomonadida
Phylum Euglenozoa
Subphylum Euglenida
Class Euglenoidea
Subphylum Kinetoplasta
Class Trypanosomatidea
11. A More Conventional Classification
Phylum Apicomplexa (aka. Sporozoa
Class Gregarinea
Class Coccidea
Phylum Mastigophora (aka Flagellata
Dinoflagellata (Many times included with the
algal forms often called Phytomastigophora
as opposed to the animal like forms called
Zoomastigophora(includesTrypanosoma and
12. Members of Axostylata have a stiffening
rod composed of microtubules, the
Axostyle. (Figure 11.11)
Members of the Class Parabasalea have a
parabasal body, which is a Golgi
apparatus connected by a fiber to one of
the kinetosomes.
Although mitochondria are absent,
members of Order Trichomonadida posses
hydrogeneosomes which are organelles
analogous to mitochondria but which
produce molecular hydrogen when oxygen
is absent.
Trichomonas vaginalis infects the
urogenital tract of humans and is sexually
13. Representative Types
Phyla Retortamonada and Axostylata

Small groups but of importance to

May represent groups derived very early
from an ancestral eukaryote before
mitochondria and plastids were
acquired by symbiogenesis.

Mitochondrial enzymes have been
reported in both groups so their
absence of mitochondria may be a
secondary derivation.

Retortamonds lack both mitochondria
and Golgi bodies (e.g., Giardia lamblia).
14. Phylum Sarcomastigophora
1. This includes two subgroups of
protozoa that move by either
pseudopodia or flagella; however,
some in each group use the method
found predominantly in the other
2. Subphylum Mastigophora: the
Flagellated Protozoa
This is divided into class
Phytomastiophorea with chlorophyll
and animal-like Zoomastigophorea
without chlorophyll.
15.  Phylum Sarcodina (the amoeba and
 Some are naked and some have
 A. Radiolaria
 B. Foraminifera
 In some classifications these are
placed in a subphylum Actinopoda
 The other members of sarcodines
are put in Rhizopoda
18. Subphylum Kinetoplasta
 a. Zooflagellates lack chromoplasts and
have holozoic or saprozoic nutrition; most
are symbiotic.
 b. Trypanosoma is an important genus of
protozoan parasites; some are not
 1) Trypanosoma brucei gambiense and T. b.
rhodesiense cause African sleeping
sickness in humans.
 2) T. brucei brucei causes a related disease
in domestic animals.
 3) These trypanosomas are transmitted by
tsetse flies; natural reservoirs include
antelope and other wild mammals.
20.  4) Half of the 10,000 new cases each
year are fatal; the remainder may
suffer brain damage.
 5) Trypanosoma cruzi causes Chagas
disease in Central and South America;
this parasite is carried by a bug and
causes nervous system problems.
 c. Leishmania species cause visceral
diseases in humans; they are
transmitted by sand flies.
 d. Various species of Trichomonas
live in the cecum, colon, mouth and
urogenital tracts of humans.
24. Subphylum Sarcodina
a. Amoeba proteus in the superclass
Rhizopoda is most commonly studied.
b. They are freshwater but require a
substratum on which to crawl.
c. The cell membrane encloses the
ectoplasm and endoplasm.
d. The nucleus, contractile vacuole
and vesicles can be seen by
e. Ameba feed on algae, protozoa,
rotifers, etc. by phagocytosis; food
vacuoles exist 15-30 hours.
26.  f. Reproduction is by binary fission using
 g. Other rhizopoda include the huge Chaos
carolinense, Amoeba radiosa with slender
pseudopodia and entozoic ameba.
 h. Entamoeba histolytica lives in the human
large intestine and attacks the intestinal
wall with enzymes, causing severe and
often fatal diarrhea.
 i. Entamoeba coli in the intestine and E.
gingivalis in the mouth are not disease
 j. Some rhizopods have a siliceous or
chitinoid test for protection; pseudopodia
project from openings.
29. k. Foraminiferans are shelled
rhizopods found mainly in oceans;
some have complex haploid and
diploid cycles.
l. Slime molds in class Eumycetozoa
live on forest detritus; they stream
together to form a pseudoplasmodium
with discrete cells or a multinucleate
plasmodium producing a fruiting body.
31. m. Radiolarians reproduce by binary
fission, budding and sporulation.
Role of Sarcodina in Building Earth
a. Hard shells of foraminiferans
and radiolarians have been
preserved since Precambrian times.
b. Abundant in the Cretaceous
and Tertiary periods, some
measured up to 100 mm in diameter!
c. One-third of the sea bottom
ooze in the Atlantic consists of
Globigerina shells.
32. d. Radiolarians have less soluble
siliceous shells and form the ooze in
Pacific and Indian oceans and fossil in
Tertiary rocks of California.
e. The White Cliffs of Dover are
sedimentary sarcodine deposits that
were uplifted.
f. Their use as indicators of rock ages
is important to oil geologists.
33. Pseudopodia (Figures 11.4, 11.5)
a. This is chief means of locomotion in
Sarcodina, many flagellates and ameboid
cells of many invertebrates and vertebrates.
b. Lobopodia are large blunt extensions of
the cell body containing both endoplasm
and ectoplasm.
c. In the limax form, the whole body moves
rather than sending out arms.
d. Filopodia are thin extensions containing
only ectoplasm; these are seen in class
e. Reticulopodia repeatedly rejoin to form a
netlike mesh.
34. f. Axopodia occur in Actinopoda.
(Figure 11.6)
1) Axial rods of microtubules
support these long thin
2) They form a geometrical array,
which is the axonome of the
3) Addition and removal of
microtubular material extends and
retracts the axopod.
4) Cytoplasm flows away from the
body on one side and toward the
body on the other.
35. 4. Superclass Actinopoda (Figure 11.17)
a. Actinopoda consist of the freshwater
class Heliozoea and three marine classes of
b. All have axopodia; and all, except
Heliozoea, have tests.
c. Radiolarians are the oldest known
protozoa; they are pelagic and live in
shallow water.
d. A central perforated capsule separates
the inner and outer cytoplasm.
e. The shell surface is fused with spines;
cytoplasm around the capsule extends
axopodia to catch prey.
41. Phylum Apicomplexa (Superphylum
1. All are endoparasites; hosts are in
many animal phyla.
2. An apical complex is a feature of this
phylum; it is present only in certain
3. Rhoptries and micronemes help it
penetrate the host’s cells.
4. Pseudopodia occur in some stages;
gametes may be flagellated and
contractile fibrils may form waves to
propel it through liquid.
42. 5. The life cycle usually includes both sexual
and asexual stages; an invertebrate may
be an intermediate host.
6. At some point, they form a spore (oocyst)
that is infective in the next host and
protects the sporozoan.
Class Sporozoea
a. Sporozoea is the most important class; it
contains three subclasses.
1) Gregarinia, or gregarines, are common
parasites of invertebrates but are of little
economic import.
2) Piroplasmia includes some veterinary
parasites: Babesia bigemina causes Texas
red-water fever in cattle.
3) Coccidia are important intracellular
parasites in both invertebrate and
43. b. Eimeria is a genus (along with
Isospora) that causes coccidiosis.
1) Isospora infections are mild
unless the immune system is weak, as
in AIDS patients.
2) Eimeria tenela is often fatal to
young fowl.
3) Organisms undergo schizogony
in intestinal cells; the zygote forms an
oocyst that passes in the feces and
releases eight sporozoites when
ingested by the next host.
44. c. Toxoplasma gondii is a parasite of cats.
1) Rodents, cattle, sheep, birds and
humans can ingest sporozoites.
2) They cross the intestine and
asexually reproduce in tissues.
3) As the host builds immunity, the
zoites enclose in tough tissue cysts called
4) Up to half of the U.S. population
carries tissue cysts from eating
undercooked meat.
5) Toxoplasmosis is a serious threat
during pregnancy; 2% of the cases of
mental retardation may be due to
congenital toxoplasmosis.
45. d. Plasmodium: The Malarial Organism
1) Malaria is the most important
infectious disease of humans.
2) Four species infect humans;
each produces different clinical
3) Anopheles mosquitoes carry all
forms; the female injects the
Plasmodium in her saliva.
4) Sporozoites penetrate liver
cells and initiate schizogony.