Protozoa 1.1 ✅ Flashcards
What are “protazoas”?
Protozoans are microscopic simple organisms which belong to a group of organisms called protists, (neither plants nor animals).
Where do protazoans exist?
On both land and water. They can be paracetic.
Who invented the “five kingdoms”?
Whittaker
(HIT TAKER)
What are the Whittaker’s 5 kingdoms?
fungi, plants, animals, protists, monerans
What environment do protozoa live in?
terrestrial, aquatic or parasitic (in vertebrate and invertebrate hosts)
Explain the structure of protozoa.
- microscopic
- eukaryotes
- unicellular eukaryotes
- display the same essential life activities as eukaryotes
- have a plasma membrane, cilia, flagella, and pseudopodia
(the outer surface of protists is called pellicle)
What are the two types of cytoplasm in protozoa?
ectoplasm and endoplasm
When is the structure of the cytoplasm best visible?
in species with projecting pseudopodia
What is the cell “mouth” called which ingests fluids and macromolecules?
cytosome or micropore
What are the forms of movement of protozoa?
- cillia
- flagellum
- pseudopodia
- subpellicular microtubules
Explain the NUTRITION of protozoa.
HOLOZOIC NUTRITION: it requires organic material.
- feed on both solid macromolecules as well as dissolved fluids
- feed through pinocytosis and phagocytosis
- feed through structures such as: CYTOSOMES or MICROPORES
AUTOTROPHIC NUTRITION:
- photosynthesis
MIXOTROPHIC NUTRITION:
- photosynthesis during the daylight
- pinocytosis and phagocytosis during the night time.
Explain the REPRODUCTION of protozoa.
- reproduce both SEXUALLY as well as ASEXUALLY
asexual examples:
1) BINARY FISSION:
(longitudinal in flagellates and transverse in the ciliates (as amoebas have no symmetry )
2) SCHIZOGONY:
(nucleus divides, and then the cytoplasm) - sexual reproduction
sexual examples:
1) GAMOGONY (must produce a GAMETE)
2) SPOROGONY (formation of an infective sporozoite)
What is the protozoic life limited by?
death of the host, or the host’s defence mechanism (eliminating the parasite or balance its reproduction to yield a chronic infection)
State the life cycle stages of a protozoan.
TROPHOZOITE.
MEROZOITE.
CYST.
What is trophozoite?
(tropho= feeding, activity and reproduction)
It is a stage in the protozoan life cycle. It is characterised by feeding, activity and reproduction.
What is merozoite?
(mero= mom= fisson)
It is a stage in the protozoan life cycle. It is the form resulting from fission of a multinucleated schizont)
What is a cyst?
(ew= hard shell, to outside environment)
protozoan cyst. infectious form of many protozoan parasites. It is usually passed in the faeces and provided with a highly condensed cytoplasm and resistant cell wall.
What is the resulting stage from sexual reproduction?
oocyst
What is “a mode of transmission”?
A mode used to transition from one host to another.
What are the four modes of transmission?
1) direct (zoite)
2) faecal-oral (zoite-cyst)
3) vector-borne (zoite-zoite)
4) predator pray (zoite-zoite)
Explain the “direct” mode of transmission.
intimate body contact (eg. sexual transmission)
Explain the “faecal-oral” mode of transmission.
environmentally-resistant cysts are passed in the feaces of one host and ingested by another host with food/water.
Explain the “vector-bourne” mode of transmission.
protozoa is taken up by blood-sucking anthropods (ie. mosquitoes), and is passed on the a new host when they next feed.
Explain the “predator-pray” mode of transmission.
protozoa are encysted (enclosed) in the tissues of pray and are eaten by the predator.
What are the different phyla of protozoa?
1) Phylum. Sarcodina
2) Phylum. Mastigophora
3) Phylum Sporozoa
4) Microsporidia
5) Ciliphora
6) Cnidosporidia
Explain shortly the phylum. Sarcodina
- no defined body shape
- no pellicle
- have pseudopodia (for locomotion)
- nutrition is holozoic or paracytic
- asexual reproduction is most common
(think of sardines)
Explain the order. Amoebida (phylum. Sarcodina)
- live in other organisms’ intestines
- paracytic
- may be carried by blood to the liver
What are the different types of orders of protozoa (in the phylum. Sarcodina)?
1) Order. Amoebida
2) Order. Testacea
3) Order. Foraminifera
4) Entamoeba Histolytica
Explain the order. Testacea. (phylum. Sarcodina)
- delicate plasma membrane
- pseudopodia for locomotion
- they have tests for siliceous material (reinforced by grains of sand)
Explain the order. Foraminifera. (phylum. Sarcodina)
- ancient group of shelled organisms found in all oceans
- mostly bottom living
- test for calcium carbonate
- slender pseudopodia
Explain shortly the phylum. Mastigophora.
- unicellular organisms
- free-living or paracytic
- elongated body, one nucleus, one or two flagellum, transparent pellicle
- reproduce by binary fission (exhibit cyst formation)
- sexual reproduction is very rare
How many phyla are protozoa classified into? How are they classified?
Protozoa are classified into six phyla. They are classified on the basis of light and electron microscopic morphology.
What is the most common form of reproduction?
binary fission (asexual)
Explain the disease Trypanosoma brucei gambriense. What phylum does it belong to?
Trypanosoma brucei gambriense is a disease in the Mastigofora phylum.
In trypanosomatids, all members are exclusively parasitic. They are parasitic to insects!
Trypasoma occurs as a paracyte in the human body.
It causes the African Sleeping Sickness.
- the species lives in african antelopes that are bitten by fly (Glossina Palpalis), “tsetse”
If the infected blood reaches a human, it causes Trypanosome fever, and then, when entering the spinal fluid, the sleeping sickness leads to death.
Explain the disease Trypanosoma cruzi. What phylum does it belong to?
Trypanosoma cruzi belongs to the mastigophora phylum.
It causes Chagas disease in humans and animals in america.
transmission: triatoma infestants deposits feces on the skin surface and bites.
known as the “kissing bug”
Explain the life cycle of Leishmania.
1) sandfly bites and taked blood
2) human: promastigotes (what the bug left) are phagocytized by macrophages.
3) promastigotes –>amastigotes
4) amastigotes multiply
5) sandy fly bites and takes blood.
6) fly: injection of parasitised cells
7) amastigotes –> promastigotes
8) divide in midgut and transfer to proboscis.
How does Leishmania look
infected hole in the skin, large belly.
Explain the Phylum. Sporozoa.
- endoparacytes
- lack locomotor structures, have a tough covering (cuticle)
- reproduce asexually by fission, and sexually by anisogamy
- life cycle may include more than one host
What classes does the Phylum. Sporozoa divide into?
1) Class. Gregarinina
2) Class. Coccidiomorpha
(intracellular parasites (vertebrates and invertebrates) species of very high medical importance)
Explain the Order. Coccidiida
- two types: eimeria and isospora
- Isospora infects humans
- Eimeria infects domestic animals
Eimeria causes severe diarrhoea or dysentery (diarrhoea with blood and mucous)
Eimeria is fatal to young fowl (severe pathogenesis in the intestine (+schizogony))
Explain the life cycle of Coccidia.
3 stages:
1) asexual reproduction: schizogony occurring in the epithelium of human intestine cells
2) sexual reproduction: gametogony. microgametes and macrogametes form.
3) sporongy: external environment. formation of oocysts and sporozoites.
How does Coccidia enter the organism?
through feeding.
What species are affected by Coccidia?
bovine, pigs, rabbits, poultry, dogs, humans
Explain Toxoplasma gondii, which Phylum it belongs to, its life cycle and more.
- paracyte of cats
- similar to cocidia yet there are also extraintestinal stages produced
- extraintestinal stages do not produce gametes but they initiate the intestinal cycle
What are the two types of taxoplasmosis?
1) ACQUIRED: increased lymph nodes, general weakness, headaches and muscular aches.
2) INNATE: taxoplasmosis enters the fetus through the placenta.
Explain Heamosporidians, which Phylum it belongs to and more.
- blood paracyte of vertabrates
- (best known is Plasmodium) causes human malaria
- malaria is a serious disease (difficult to control, in tropical and sub tropical countries)
- Heamosporidians belong to the sporozoa phylum.
Explain the life cycle of Malaria parasites.
2 phases:
1) Endogenous = Asexual cycle = in humans = Schizogony
- schizogony (|nucleus and cytoplasm divides)
2) Exogenous phase = sexual cycle = in mosquitoes = sporongy (occurs outside the host)
Explain the Phylum. Microsporidia.
- eukaryotic, unicellular organisms
- spore-forming, intracellular
- invade vertebrates and invertebrates
- important in fisheries
- microsporidia has been known to parasite those with health immune systems.
State an example of a microsporadian paracyte.
Nosema Bombycis
Nosema Apis
Explain Nosema Bombycis
- microsporidian parasite
- produces paper like spots on caterpillars
- disease known as “pebrine”
- highly infectious (pass from mother moth to eggs)
Explain Nosema apis
small, single celled paracyte afecting HONEY BEES.
- it causes nosemosis
- it is parasitic but talked about as a disease
- single spore causes infection, normally 20-90 are found per bee.
What are the symptoms of Nosema apis
- dysentery
- shorter life of worker bees
- lack of industry in the colony
- lower tendency to sting
- crawling bees
- disjoined wings
- swollen abdomens
Explain the phylum Ciliphora
- aquatic and free-living forms
- presence of cilia (as locomotor structures)
- have a pellicle
- reproduce asexually by binary fission, and sexually by conjugation (exchange of genetic material).
Why do protozoa have contractile vacuoles?
for osmoregulation.
Which structures occur in paracytic protozoa?
Golgi apparatus,
mitochondria,
lysosomes,
food vacuoles,
conoids
Explain the order Entamoeba Histolytica.
- human large intestines,
- invades the intestinal wall by secreting enzymes which attack the intestinal lining,
- can travel to the liver by blood,
- spread with water or food (containing cysts)
Explain the main features of the Phylum. Cnidosporidia.
How do they reproduce?
- characterized by spores
- life cycle is complex and incompletely understood
1-7 spore shell valves
1-2 amoeboid infective germs
2-7 nematocyst-like polar capsules
