15. Protozoa Flashcards
What is a protozoa?
a single celled organism with nuclei
what does Protozoa mean?
first animal
what kingdom is Protozoa part of?
Protists
what does the kingdom Protista include?
single-celled organisms, including the Dinoflagellates, and the single celled algae
in general, do Protozoans photosynthesize?
no
are Protozoans generallt motile?
yes
where can protozoans live in the body?
in all parts of the body, including the gut, mouth, skin, blood, live, spleen, genital tract, lungs brain and heart
what are the different groups of Protozoa, of which parasitize humans?
Amoeba
Flagellates
Ciliates
Sporozoa
what Protozoan group is Entamoeba in?
Amoeba
what Protozoan group are Giardia, Trichonomas, Trypanosoma and Leishmania in?
Flagellates
do protozoa have rigid cell walls?
no
how do protozoa digest their food?
in vacuoles
how do protozoa gain entry to a host?
orally or through the bite of a blood-sucking vector
T/F
•
From the point of view of functional and physiological
complexity, a protozoan is more like an animal than like
a single cell.
True
define niche selection
selected to live in a specific essential niche
defined by anatomical, physiological and biochemical
features of the site
what is pathogenesis related to?
the niche, the metabolic requirements of the parasite and the population density
what are some ways that protozoa will feed/ingest nutrients?
active transport, phagocytosis, or pinocytosis
where does digestion take place in protozoa?
in a vacuole through lysosomal enzymes
how is waste excreted in protozoa?
by diffusion or exocytosis
what protozoan group is Balantidium coli in?
ciliates
how do amoebas move?
pseudopodia
how do flagellates and ciliates move?
cilia and flagella
how are cilia and flagella microtubules arranged?
9+2
how do protozoa reproduce asexually?
binary fission
multiple fission
budding
i.e. variations of mitotic division
how do protozoa reproduce sexually?
gamete fusion
conjugation
what is schozogony?
multiple fission
describe binary fission
mitosis leads to the cell splitting yielding two daughter cells
describe multiple fission
nucleus undergoes multiple divisions before the cell divides - gives rise to multiple daughter cells
which protozoa are more likely to reproduce sexually, through gamete fusion?
the ones with an insect vector phase
define trophozoite
any stage in a protozoan’s life cycle which can ingest nutrients. In practice it refers to the motile form (pseudopods, cilia, flagella)
define cyst
Non‐motile form, protected by a membrane. Often the *infective stage*
define excystation
process of emergence of the trophozoite from the cyst
what disease does Giardia intestinalis cause?
giardiasis
where is giardiasis acquired?
contaminated water
what disease does Trichonomas vaginalis cause?
vaginosis
what disease does Trypanosoma brucei gambiense cause?
african sleeping sickness
what disease does Entamoeba histolytica cause?
Amoebic dyentery
how is african sleeping sickness transmitted?
the tsetse fly
what disease does Tripanosoma cruzi cause?
chagas disease
how is T. cruzi transmitted?
the kissing bug
what disease does Leishmania spp. cause?
leishmaniasis
how is leishmaniasis transmitted?
sand flies
what is the phylum of Entamoeba histolytica?
Sarcodina
who is in the phylum Mastigophora?
Giardia intestinalis, Trichomonas vaginalis, , Trypanosoma brucei gambiense, Trypanosoma cruzi, and Leishmania?
what disease does Balantidium coli cause?
Balantidial dyentery
how is B. coli contracted?
contaminated water
what phylum is B. coli in?
Ciliata
what disease does Plasmodium spp. cause?
malaria
how is Plasmodium spp. transmitted?
Anopheles mosquito
what phylum is Plasmodium spp. in?
Sporozoa (apicomplexans)
what disease does Toxoplasma gondii cause?
toxoplasmosis
what phylum is Toxo in?
Sporozoa (apicomplexans)
how can Toxo be contracted?
raw meat, cat feces
what disease does Cryptosporidium cause?
Diarrhea
what phylum is Cryptosporidium in?
Sporozoa (apicomplexams)
how is Cryptosporodium spread?
humans, animals
What is this?
Malaria - Plasmodium spp.
What is this?
Toxoplasmosis (Toxoplasma gondii)
What is this?
Criptosporidiosis - Cryptosporidium parum
What are the symptoms of Toxo?
Does not cause symptoms in most people. Can cause fatalities in unborn children and in AIDS patients.
how can Toxo be prevented?
Thoroughly cook all meats, be careful handling cat litter, feed cats commercial cat food, cover sand boxes when not in use and wash all fruits and vegetables before eating.
what are the symptoms of Plasmodium spp.?
fever, headache and vomiting, can be fatal
how can Plasmodium spp. be prevented?
Spread by mosquito bites. The use of DDT in the U.S. and many other countries brought malaria under control. It is still a problem in many developing countries.
what are the symptoms of C. parvum?
Diarrhea. May also cause vomiting, headache, fever and stomach cramps. Can be fatal to those in poor health.
how can C. parvum be prevented?
Use an approved water filter, an approved brand of bottled water or boil water for 1 minute. Avoid drinking water from lakes and rivers.
T/F
•
Apicomplexa consists of all parasitic species
True
do apicomplexa have cilia or flagella?
not usually
what is the hallmark of Apicomplexa
apical complex structure
what do most Apicomplexa possess
the apicoplast organelle
what is the appearance of the apical complex?
An organ complex of the Apicomplexa that appears as a
conical structures on the tapered end (or the apical end) of
the cell, and contains rhoptries, micronemes, dense
granules, polar rings, and a conoid.
what is the mechanism of the apical complex?
• Rhoptries, micronemes and dense granules discharge
substances into the host cell during the invasion process
through a system of ducts which open up at the apical end.
• The substances released play a crucial role in destabilizing
the host cell membrane and in formation of an invasion pit.
name the structures
what is the use of the apical complex?
it is involed in penetrating the host
how many membranes does the apical complex have?
4
why is the apicomplast also known as the plastid?
drugs against chloroplasts and prokaryotes also kill apicomplexan parasites
how did the apicomplast likely become encased in four membranes?
via a secondary endosymbiotic event - the promary endosymbiosis gives rise to 2 membranes, and then if that is endocytosed again you will have 4 membranes
what is primary endosymbiosis?
the capture of a cyanobacterium by a eukaryotic heterotroph - the cyanobacterium would have modified during evolution to give rise to a plastid with two surrounding membranes
what is secondary endosymbiosis?
proposed to be the engulfment of a red algae containing a chloroplast by a eukaryotic heterotroph - the red algae would have become the plastic with four ssurrounding membranes
is the apicomplast a chloroplast?
NO
do apicomplasts have chloroplasts?
NO they are absent
is the apicomplast vital for the pasite’s survival?
yes
what is the apicomplast possibly involved in?
lipid metabolism
if we remove the apicomplast, what is the effect on the parasite?
they will survive but they will not be able to invade new hosts
