Protozoa, Helminths & Related Microbiology Vocabulary

Vocabulary flashcards covering key parasites, life-cycle terms, diseases, and genetic concepts discussed in the lecture.

Protozoa

Single-celled eukaryotic parasites lacking chloroplasts; may cause millions of human infections each year.

Helminths

Visible parasitic worms (flatworms & roundworms) that infect humans and other hosts.

Trophozoite

Active, mobile, feeding stage of a protozoan that requires moisture and nutrients.

Cyst (Protozoan)

Dormant, resistant stage of a protozoan; often the infective form ingested by humans.

Pseudopod

"False foot" extension of cytoplasm used by some protozoa for movement and feeding.

Flagellum

Whip-like appendage that propels certain protozoa through fluids.

Cilium

Short, hair-like structure that helps protozoa move in patterns and attach to surfaces.

Saprobe (Saprophyte)

Organism that scavenges and feeds on dead plants or animals.

Fecal-oral transmission

Spread of pathogens via ingestion of food or water contaminated with feces.

Amoeba

Protozoan group that moves with pseudopods; forms trophozoites and cysts.

Entamoeba histolytica

Intestinal amoeba causing amebiasis—bloody, mucus-filled diarrhea and possible liver abscesses.

Naegleria fowleri

Free-living amoeba that enters via the nose and causes fatal primary amoebic meningoencephalitis.

Giardia lamblia

Flagellated protozoan that causes giardiasis—watery diarrhea and excessive flatulence.

Trichomonas vaginalis

Sexually transmitted flagellate causing trichomoniasis of the urogenital tract.

Trypanosoma brucei

Hemoflagellate transmitted by tsetse flies; agent of African sleeping sickness.

Trypanosoma cruzi

Hemoflagellate spread by kissing bugs; causes Chagas disease with cardiac enlargement.

African Sleeping Sickness

Disease marked by extreme fatigue and hypersomnia, produced by Trypanosoma brucei.

Chagas Disease

Chronic infection by Trypanosoma cruzi leading to cardiomyopathy and other systemic damage.

Leishmania donovani

Protozoan transmitted by sandflies; causes visceral or cutaneous leishmaniasis with skin lesions.

Plasmodium species

Mosquito-borne protozoa (e.g., P. falciparum, P. vivax) responsible for malaria.

Malaria

Disease in which Plasmodium parasites invade and destroy red blood cells, producing fever and anemia.

Sickle Cell Trait

Inherited hemoglobin variant that confers resistance to Plasmodium infection.

Toxoplasma gondii

Protozoan from cat feces that causes toxoplasmosis, forming brain cysts especially in immunocompromised or pregnant hosts.

Toxoplasmosis

Flu-like or neurologic illness from Toxoplasma gondii; risk to fetuses and AIDS patients.

Cryptosporidium

Non-motile protozoan causing self-limiting watery diarrhea (cryptosporidiosis).

Cyclospora

Non-motile coccidian protozoan causing prolonged diarrhea after food or water exposure.

Flatworms (Platyhelminthes)

Helminths with flattened bodies; include cestodes (tapeworms) and trematodes (flukes).

Roundworms (Nematodes)

Cylindrical helminths such as Ascaris; have separate sexes and complete digestive tracts.

Cestodes (Tapeworms)

Segmented flatworms that inhabit intestines; relatively easy to treat.

Trematodes (Flukes)

Unsegmented flatworms; some (e.g., blood, liver, bladder flukes) can cause serious disease and cancers.

Ascaris lumbricoides

Large intestinal roundworm that can emerge from nose or mouth; causes obstruction.

Taenia solium

Pork tapeworm; larval cysticerci in humans cause neurocysticercosis when reaching the brain.

Schistosoma (Blood Fluke)

Trematode that penetrates skin in water, leading to schistosomiasis with systemic symptoms.

Intermediate Host

Animal that harbors larval or asexual stages of a parasite before it reaches humans.

Lac Operon

Inducible gene system in E. coli that switches on enzymes for lactose metabolism when lactose is present.

Operon

Cluster of bacterial genes regulated together, containing promoter, operator, and structural genes.

Repressor Protein

Protein that binds an operator to block transcription when the substrate is absent.

Conjugation (Bacterial)

Transfer of plasmid DNA between bacteria via a sex pilus; a form of genetic exchange.