Parasites lab exam 2

What are the major differences between Cyclophyllidean and Pseudophyllidean tapeworms?

Cyclophyllidea have 4 suckers and may have hooks; Pseudophyllidea have 2 bothria and no hooks.

What are the three major body parts of a tapeworm?

Scolex (attachment), Neck (forms new proglottids), Strobila (chain of proglottids).

What is the function of the scolex in tapeworms?

Attachment to the host.

What type of eggs do Cyclophyllidean tapeworms produce?

Thick-shelled, non-operculated eggs with radial striations and an oncosphere with 6 hooks.

What is the life cycle of Pseudophyllidean tapeworms?

Always aquatic; involves copepod and fish as intermediate hosts.

What is a distinguishing feature of Taeniid Cyclophyllidean proglottids?

Single genital pore on the side and tree-like uterus in gravid proglottids.

What are the identifying features of Hymenolepis eggs?

Thin shell, oncosphere with 6 hooks, often has polar filaments.

How can you differentiate between Fasciola and Paragonimus eggs?

Fasciola eggs are large, brown/yellow, operculated; Paragonimus eggs are golden-brown with a thick shell and distinct shoulders.

What are the key identifying features of trematodes?

Leaf-shaped, dorsoventrally flattened, two suckers, blind gut, hermaphroditic.

What are the life cycle stages of a fluke?

Egg, Miracidium, Sporocyst, Redia, Cercaria, Metacercaria, Adult.

What is the main difference between trophozoite and cyst stages in protozoa?

Trophozoite is the active feeding stage; cyst is the dormant, resistant transmission stage.

What is the role of cilia in ciliates?

Cilia are used for coordinated movement.

What distinguishes flagellates from other protozoa?

Flagellates move using 1 to several whip-like flagella.

What is the significance of nuclear morphology in protozoa?

It helps distinguish closely related species and differentiate pathogenic from non-pathogenic forms.

What are the characteristics of the cercaria stage in trematodes?

Free-swimming larva with a tail, oral and ventral suckers present.

What is the function of the ventral sucker in trematodes?

Attachment to the host.

What type of organisms can be found in pond water samples?

Protozoa (ciliates, amoebas, flagellates), metazoans (rotifers), nematodes, and algae.

What is the primary method of movement for amoebas?

Amoebas move using pseudopodia, which are extensions of their cytoplasm.

What is a unique feature of schistosomes among trematodes?

Schistosomes have separate sexes.

What is the larval development sequence in Pseudophyllidean tapeworms?

Coracidium → procercoid → plerocercoid.

What type of eggs do Taenia produce?

Thick-walled, radially striated eggs.

What is the appearance of Moniezia eggs?

Triangle or square-shaped with a pyriform apparatus.

What is the role of the uterus in trematodes?

It is a coiled tube that stores eggs.

What is the significance of calcareous corpuscles in cestodes?

They are diagnostic features used to identify cestodes.

What is the function of the cirrus sac in mature proglottids?

It contains the cirrus, the male copulatory organ.

What is the role of trophozoites in protozoa?

Feeding, dividing, active stage

What is the role of cysts in protozoa?

Dormant, resistant, transmission stage

How do ciliates move?

Using coordinated beating of many short hair-like structures called cilia

What is the distinguishing feature of flagellates?

They move using 1 to several flagella

What is the movement mechanism of amoebas?

Using pseudopodia, where cytoplasmic streaming pushes the membrane outward

How do coccidia (Apicomplexa) move?

They exhibit gliding motility using an actin-myosin motor

What is the appearance of Giardia trophozoites in stained smears?

Two nuclei resembling 'eyes', median bodies, pear-shaped body, and four pairs of flagella

What are the identifying features of Balantidium coli?

Large, kidney-shaped macronucleus

What is a key feature of Entamoeba cysts?

Multiple nuclei depending on species, with chromatoid bars and peripheral chromatin

What are the general features of stained slides using Trichrome stain?

Cytoplasm appears blue-green, nuclei appear red/magenta

What does Iron-hematoxylin stain reveal?

Nuclei appear dark blue-black, excellent for nuclear detail

What does Giemsa stain show in protozoan identification?

Cytoplasm appears blue, nuclei appear pink/purple

What is the difference between fecal cysts and tissue cysts?

Fecal cysts are passed in feces and environmentally resistant; tissue cysts form inside host tissues

What is the appearance of Giardia trophozoites under Giemsa stain?

Cytoplasm is bluish, nuclei are reddish-magenta, with a bilaterally symmetrical 'old man with glasses' appearance

What are the characteristics of protozoan locomotion?

Cilia for ciliates, flagella for flagellates, pseudopodia for amoebas, and gliding for coccidia

What are the distinguishing features of Trichomonas trophozoites?

Multiple flagella and an undulating membrane

What are the key identifying features of Entamoeba trophozoites?

Single nucleus with a central karyosome

What is the primary function of the apical complex in Apicomplexa?

Essential for host cell invasion

What unique organelles are found in Toxoplasma gondii?

Several unique secretory and apical organelles that drive invasion

What is the appearance of Balantidium trophozoites?

Large, ciliated, with a visible macronucleus

What is the difference in environment for trophozoites and cysts?

Trophozoites live inside the host; cysts survive outside the host

What is the infectivity status of trophozoites compared to cysts?

Trophozoites are usually not infective; cysts are usually infective

What are median bodies in Giardia trophozoites?

Structures that resemble mustache or eyebrows

What is the significance of observing nuclear morphology in stained preparations?

It is an excellent diagnostic tool for identifying protozoan species

What are the observable structures in trophozoites?

Nucleus, cytoplasm, and organelles

What is the function of rhoptries in Toxoplasma?

Inject proteins into the host cell to form a moving junction and modify the host environment.

What do micronemes do during Toxoplasma invasion?

They are the first to secrete during invasion, allowing gliding motility and attachment to the host cell.

What is the role of dense granules in Toxoplasma?

Secreted after invasion into the parasitophorous vacuole to remodel the vacuole.

What is the conoid in Toxoplasma?

A cone-shaped structure used for penetration into host cells.

What is the function of the apicoplast in Toxoplasma?

A non-photosynthetic plastid essential for lipid synthesis.

What is the Inner Membrane Complex (IMC) in Toxoplasma?

A scaffold beneath the plasma membrane involved in daughter cell formation.

What are the four major stages of the lytic cycle of Toxoplasma gondii?

1. Attachment to host cell, 2. Active invasion using apical complex, 3. Intracellular replication within a parasitophorous vacuole, 4. Egress by rupturing host cell.

Why is it called the lytic cycle?

Because parasites replicate inside the parasitophorous vacuole until they burst (lyse) the host cell during egress.

What triggers egress in Toxoplasma gondii?

Calcium (Ca²⁺) is critical for triggering microneme secretion and is required for parasite motility and host-cell exit.

Where does Toxoplasma gondii live inside the host cell?

Inside a parasitophorous vacuole, not freely in the cytoplasm.

What is the method of cell division in Toxoplasma?

Endodyogeny, where two daughter cells form within the mother cell.

What is the morphology of Trypanosoma cruzi?

Extracellular, curved or 'C-shaped', with a large posterior kinetoplast and less pronounced undulating membrane.

What distinguishes Trypanosoma evansi from Trypanosoma cruzi?

T. evansi may have a smaller or absent kinetoplast and is slightly more slender.

What are the key features of Plasmodium vivax merozoites?

Ring forms inside RBCs, small blue cytoplasm ring with red chromatin dot, and enlarged RBCs.

What are the distinguishing features of Babesia spp. merozoites?

Round to pear-shaped, usually 2 per RBC forming paired merozoites, occasionally 4 forming the 'Maltese cross'.

What is the significance of the kinetoplast in Trypanosoma?

It is a unique mitochondrial DNA structure located near one end of the cell and is key for diagnosis.

What is the function of the undulating membrane in Trypanosoma?

It aids in movement through the blood plasma.

What are the differences in morphology between Babesia and Plasmodium in RBCs?

Babesia has paired or Maltese cross merozoites with no pigment, while Plasmodium has ring forms and may cause RBC enlargement.

What is the first appearance of daughter cells in Toxoplasma?

The first strip with small red IMC buds.

What happens during the egress stage of Toxoplasma's lytic cycle?

The parasite ruptures the host cell, releasing new tachyzoites.

What is the role of dense granule proteins (GRA proteins) in Toxoplasma?

They modify the parasitophorous vacuole membrane, build a network inside the vacuole, and alter host immune signaling.

What is the general morphology of trypomastigotes?

They can be C-shaped, S-shaped, or snake-like, with a central nucleus and a flagellum.

What is the significance of the IMC in Toxoplasma?

It is involved in the formation of daughter cells and supports the structure beneath the plasma membrane.

What is the replication rate of mutant vs wildtype Toxoplasma?

The mutant strain has fewer parasites per vacuole and grows slower due to fewer rounds of endodyogeny.

What is the role of the flagellum in Trypanosoma?

It extends from the kinetoplast end and is used for movement through blood plasma.