Chapter 12: Microbiology – Algae, Protozoa, Helminths & Arthropod Vectors

Vocabulary flashcards summarizing essential terms and definitions from lecture notes on algae, protozoa, helminths, and arthropod vectors.

Algae

Non-taxonomic group of unicellular or filamentous photoautotrophs lacking roots, stems & leaves, mostly aquatic.

Thallus

Body of a multicellular alga, composed of holdfasts, stipes & blades.

Holdfast

Root-like anchoring structure at the base of an algal thallus.

Stipe

Stem-like portion of an algal thallus that supports blades.

Blade (Algae)

Leaf-like, photosynthetic region of a multicellular alga.

Pneumocyst

Gas-filled bladder that provides buoyancy to certain algae.

Alternation of Generations

Sexual life cycle in some multicellular algae that alternates haploid and diploid stages.

Brown Algae (Phaeophyta)

Multicellular kelp with cellulose & alginic acid walls; source of food thickener algin.

Red Algae (Rhodophyta)

Branched multicellular algae living at great depths; produce agar, carrageenan, & occasional toxins.

Green Algae (Chlorophyta)

Unicellular or multicellular algae with cellulose walls, chlorophyll a & b; ancestral to land plants.

Diatoms (Bacillariophyta)

Unicellular algae with silica & pectin walls; some produce domoic acid toxins.

Dinoflagellates

Unicellular planktonic algae with cellulose in plasma membrane; produce saxitoxin (paralytic shellfish poisoning).

Water Molds (Oomycota)

Chemoheterotrophic organisms once grouped with algae; cellulose walls, produce parasitic hyphae.

Chlorophyll a

Primary photosynthetic pigment present in all algae.

Accessory Pigments

Additional light-absorbing molecules (e.g., chlorophyll c, carotenoids, phycobiliproteins) giving algae distinctive colors.

Protozoa

Unicellular eukaryotes with animal-like nutrition, complex life cycles, often water or soil inhabitants.

Trophozoite

Feeding and growing stage of a protozoan.

Cyst (Protozoa)

Dormant, protective stage enabling protozoa to survive adverse conditions.

Schizogony

Asexual multiple fission producing many daughter cells simultaneously in protozoa.

Pellicle

Flexible outer covering of many protozoa that provides shape & protection.

Cytostome

Mouthlike opening through which ciliates ingest food.

Anal Pore

Excretory opening in some protozoa for waste elimination.

Excavata

Superclade of spindle-shaped protozoa possessing flagella; includes Diplomonads, Parabasalids & Euglenozoa.

Diplomonads

Excavata lacking mitochondria; multiple flagella; includes Giardia intestinalis.

Giardia intestinalis

Diplomonad intestinal parasite transmitted by fecal-oral cysts in contaminated water.

Parabasalids

Excavata with undulating membrane; no cyst stage; e.g., Trichomonas vaginalis.

Trichomonas vaginalis

Parabasalid causing STD trichomoniasis; lacks cysts, transmitted directly.

Euglenozoa

Excavata with disk-shaped mitochondria; includes photoautotrophic euglenas & hemoflagellate parasites.

Hemoflagellates

Blood parasites (e.g., Trypanosoma spp.) transmitted by insect vectors.

Trypanosoma

Genus of hemoflagellates causing African sleeping sickness & Chagas disease.

Amoebozoa

Protozoa that move using pseudopods; includes Entamoeba histolytica.

Entamoeba histolytica

Amoeba causing amebic dysentery, transmitted by waterborne cysts.

Acanthamoeba

Amoeba infecting cornea & brain, leading to blindness or encephalitis.

Balamuthia

Amoeba causing granulomatous amebic encephalitis (GAE).

Apicomplexa

Nonmotile, obligate intracellular protozoan parasites with complex life cycles (e.g., Plasmodium).

Plasmodium

Apicomplexan genus causing malaria; sexual stage in Anopheles mosquito, asexual in humans.

Toxoplasma gondii

Apicomplexan transmitted by cat feces; dangerous to fetuses & immunocompromised patients.

Cryptosporidium

Apicomplexan causing waterborne diarrheal illness; severe in immunocompromised hosts.

Ciliates

Protozoa that move by coordinated cilia; only human pathogen is Balantidium coli.

Balantidium coli

Ciliate causing dysentery in humans.

Definitive Host

Organism in which a parasite undergoes sexual reproduction.

Intermediate Host

Organism in which a parasite undergoes asexual development or larval stages.

Helminths

Multicellular parasitic worms; include flatworms (platyhelminths) & roundworms (nematodes).

Dioecious

Having separate male and female individuals.

Monoecious (Hermaphroditic)

Having both male & female reproductive organs in one individual.

Platyhelminths

Flatworms comprising trematodes (flukes) & cestodes (tapeworms).

Trematodes

Leaf-shaped flukes with oral & ventral suckers; absorb nutrients through cuticle.

Paragonimus spp.

Lung flukes transmitted via ingestion of infected crayfish or crab; humans are definitive hosts.

Schistosoma

Blood flukes penetrating skin of humans; snails are intermediate hosts.

Cestodes

Tapeworms with scolex & proglottids; absorb nutrients through surface.

Scolex

Head of a tapeworm bearing suckers (and sometimes hooks) for attachment.

Proglottid

Segment of a tapeworm containing both male & female reproductive organs.

Cysticercus

Larval bladder stage of Taenia solium in intermediate host tissues.

Hydatid Cyst

Large fluid-filled larval cyst of Echinococcus granulosus in intermediate hosts (including humans).

Taenia solium

Pork tapeworm; humans are definitive hosts when ingesting cysticerci in undercooked pork.

Echinococcus granulosus

Tapeworm causing hydatid disease; dogs definitive hosts, humans accidental intermediate hosts.

Nematodes

Cylindrical roundworms with complete digestive tract; many parasitic species.

Sexual Dimorphism (Nematodes)

Distinct morphological differences between male and female worms.

Ascaris lumbricoides

Large intestinal nematode; eggs infective via fecal-oral route.

Baylisascaris procyonis

Raccoon roundworm capable of causing severe larval migrans in humans.

Trichuris trichiura

Whipworm infecting human large intestine; eggs infective.

Enterobius vermicularis

Pinworm; perianal egg deposition causes itching; common in children.

Necator americanus

Hookworm; larvae penetrate skin & migrate to intestines.

Ancylostoma duodenale

Old World hookworm with life cycle similar to Necator americanus.

Dirofilaria immitis

Heartworm of dogs & cats; mosquito-borne larvae infect heart & pulmonary arteries.

Arthropod Vectors

Segmented animals with jointed legs that transmit pathogens (e.g., mosquitoes, ticks, fleas).

Mechanical Transmission

Pathogen carried on arthropod’s body surface without multiplication.

Biological Transmission

Pathogen multiplies within vector before transmission to host.

Dermacentor tick

Arachnid vector of Rocky Mountain spotted fever.

Ixodes tick

Vector of Lyme disease, babesiosis & ehrlichiosis.

Aedes mosquito

Vector of dengue, Zika & heartworm (Dirofilaria immitis).

Anopheles mosquito

Definitive host & vector for Plasmodium (malaria).

Glossina (Tsetse fly)

Vector of African trypanosomiasis (sleeping sickness).

Triatoma (Kissing bug)

Vector of Trypanosoma cruzi, agent of Chagas disease.

Vector Definitive Host

When the vector itself is the organism where the parasite’s sexual stage occurs (e.g., mosquito for Plasmodium).