Lecture 13- Protozoa Flashcards
what kingdom are Protozoa from?
Kingdom Protista
what is the main characteristic of Kingdom Protista?
made up of all single-celled organisms
how are protozoans generally defined?
protists that exhibit more “animal-like” characteristics than other groups (commonly motile and do not generally photosynthesize)
protozoans live in what parts of the body?
gut, mouth, skin, blood, liver, spleen, genital tract, lungs, brain, and the heart
what are the groups of protozoa that infect humans?
- Amoebae
- Flagellates
- Ciliates
- Sporozoa
what are the species of each of the four infectious protozoan groups?
- Amoeba: Entamoeba
- Flagellata: Trypanosoma, Leishmania, Giardia
- Sporozoa: Plasmodium, Toxoplasma, Cryptosporidium
- Ciliates: Balantidium
what are some general notes of protozoa?
- exhibit a wide variety of morphologies
- less than 50um in size
- have a complex subcellular organization
- no rigid cell walls
- all digest their food in vacuoles
- often gain host entry orally or through the bite of blood sucking vectors
- carry out complex metabolic activities
- organelles have similar functions to those of higher animals
- more like an animal than a single-cell
what is the niche selection of protozoa?
selected to live in a specific essential niche defined by anatomical, physiological and biochemical features of the site
what is protozoa pathogenesis related to?
niche, metabolic requirements of the parasite, and population density
what does the complex life cycle of protozoa involve?
- sexual and asexual reproduction
- mainly form a resistant cyst stage
how do protozoa ingest nutrients?
either via active transport, phagocytosis or pinocytosis
protozoa have traditionally been divided on the basis of their means of ____
locomotion
protozoa reproduce asexually by …
-binary fission
-multiple fission
(variations on mitotic division)
protozoa reproduce sexually by …
gamete fusion
where does gamete fusion occur?
mainly in protozoa with an insect vector stage
definition of a trophozoite:
any haploid stage in a protozoan’s life cycle which can ingest nutrients. in some parasites it is the motile form
definition of a cyst:
non-motile form, protected by a membrane. often the ‘infective stage’
definition of excystation:
process of emergence of the trophozoite from the cysts
what group of protozoa are the apicomplexan parasites?
sporozoa (plasmodium, toxoplasma, cryptosporidium)
what are the stages of the typical apicomplexan life cycle?
- sporozoite
- merozoites
- micro- and macro- gametocytes
- zygote
- oocyst containing sporocysts and/or sporozoites
definition of sporogony
multiple fission of a zygote
definition of sporozoite
daughter cell resulting from sporogony
definition of schizogony
fission of sporozoites where multiple mitoses take place followed by simultaneous cytokineses, resulting in many daughter cells all at once
definition of gametogony
production of gametes
definition of a zygote
fusion of gametes (meiosis may occur after fusion)
what are the general characteristics of apicomplexa
- all species are parasitic
- many of important health and veterinary significance
- without cilia or flagella
- complex life cycles
- have an apical complex structure involved in penetrating a host’s cell
- most possess a unique organelle called the apicoplast
what is the apical complex?
involved in invasion of an animal cell that contains rhoptries, micronemes, dense granules, polar rings, and a conoid. These parts secrete substances into the host cell during the invasion process out through the apical end.
how many membranes does the apicoblast have?
4
what is the apicoplast origin?
came from primary endosymbiosis which involved the capture of a cyanobacterium by a eukaryotic heterotroph. A secondary endosymbiotic event then involved the engulfment of the eukaryotic heterotroph by another eukaryotic heterotroph
the apicoplast organelle is not a …
chloroplast
what would deletion of the apicoplast do to the parasite?
prevent it from invading host cells
what are the symptoms of toxoplasma gondii?
does not usually cause symptoms in most people. Can cause fatalities in unborn children and in AIDS patients
what are the symptoms of plasmodium spp?
fever, headache and vomiting. can be fatal.
what are the symptoms of cryptosporidium parvum?
diarrhea. may also cause vomiting, headache, fever and stomach cramps. can be fatal to those in poor health.
malaria is found …
worldwide
since the 1950s, malaria …
has been successfully eliminated from many regions including Europe, North America and certain areas in the Caribbean
what is malaria?
- a life-threatening infectious disease caused by protozoan parasites of the genus Plasmodium
- the third cause of death from an infectious pathogen worldwide
what kind of parasite is malaria?
obligate intracellular parasite
how are malaria parasites transmitted from one person to another?
by the bite of a female Anopheles mosquito
what are the four parasite species that cause malaria in humans?
- plasmodium falciparum
- plasmodium vivax
- plasmodium malariae
- plasmodium ovale
what are the major features of P. falciparum?
- the most important species as it is responsible for about 50% of all malaria cases worldwide and nearly all morbidity and mortality from severe malaria
- found in tropics and sub-tropics
what are the major features
of P. vivax?
- the malaria parasite with the widest geographical distribution
- seen in tropical and sub-tropical areas but rare in Africa
- estimated to cause 43% of all malaria cases in the world
what are the major features of P. ovale?
- this species is relatively rarely encountered
- primarily seen in tropical Africa, especially, the west coast, but has been reported in South America and Asia
what are the major features of P. malariae?
- responsible for only 7% of malaria cases
- occurs mainly in sub-tropical climates
