Microbiology BIOL 2161 - Chapter 5: The Eukaryotes of Microbiology

Comprehensive vocabulary flashcards covering the characteristics, life cycles, taxonomy, and medical relevance of unicellular eukaryotic parasites, parasitic helminths, fungi, algae, and lichens from Medical Microbiology BIOL 2161 Chapter 5.

Plankton

Microorganisms that drift or float in water and are moved by currents.

Zooplankton

Motile and nonphotosynthetic plankton.

Phytoplankton

Photosynthetic plankton.

Trophozoites

The feeding and growth stage of protozoans during which they feed on small particulate food sources such as bacteria.

Cyst

A protozoan cell surrounded by a protective wall formed when environmental conditions are too harsh for the trophozoite.

Encystment

The process by which a protozoan trophozoite transforms into an encapsulated cyst.

Excystment

The reactivation process triggered by environmental cues that restores cysts to active trophozoites when conditions improve.

Schizogony

A form of asexual reproduction in protozoans wherein the cell nucleus divides multiple times before the cell divides into many smaller cells.

Merozoites

The cellular products formed through schizogony that are stored inside structures known as schizonts.

Syngamy

A sexual reproductive process in protozoans in which haploid gametes fuse.

Protist Conjugation

A true form of eukaryotic sexual reproduction occurring between two cells of different mating types, found in ciliates.

Plasmalemma

The protozoan plasma membrane.

Pellicle

A rigid structure formed by protein bands located just beneath the plasma membrane in certain protozoans.

Ectoplasm

The outer gel layer of cytoplasm positioned beneath the membrane that contains microfilaments of actin.

Endoplasm

The inner, fluid (sol) region of cytoplasm situated inside the ectoplasm layer.

Cytostome

A specialized protozoan structure used for ingesting food particles via phagocytosis.

Cytoproct

A specialized protozoan cellular structure dedicated to the exocytosis of metabolic wastes.

Holozoic

Describing protozoans that ingest whole food particles through phagocytosis.

Saprozoic

Describing protozoans or fungi that ingest small, soluble food molecules.

Pseudopodia

Cytoplasmic extensions ('false feet') used to attach to surfaces and move protist cells forward through cytoplasmic flow.

Contractile Vacuoles

Organelles utilized by certain protists to expel water from the cell for osmotic regulation and salt-water balance.

Polyphyletic Group

A taxonomic grouping of organisms, such as protists, that lacks a shared evolutionary origin.

Entamoeba histolytica

A medically important amoebozoan transmitted via cysts in feces that serves as the primary cause of amoebic dysentery.

Naegleria fowleri

The 'brain-eating amoeba' classified under Amoebozoa, found in warm freshwater, which causes primary amoebic meningoencephalitis (PAM).

Acanthamoeba

An amoebozoan capable of causing keratitis (corneal inflammation) and blindness.

Cellular Slime Molds

Slime molds that exist as individual amoeboid cells that aggregate into a mobile slug before developing a fruiting body that yields haploid spores.

Plasmodial Slime Molds

Slime molds that exist as large, multinucleate amoeboid cells that generate reproductive stalks to yield spores dividing into gametes.

Apical Complex

A concentration of organelles, vacuoles, and microtubules located at one end of an apicomplexan that facilitates entry into host cells.

Theileria (Babesia) microti

An apicomplexan transmitted by the tick Ixodes scapularis that triggers recurring, potentially fatal fever and acts as a transfusion-transmitted pathogen in the United States.

Toxoplasma gondii

An apicomplexan causing toxoplasmosis, acquired through cat feces, unwashed produce, or undercooked meat, which poses serious birth defect risks.

Balantidium coli

The only parasitic ciliate known to infect humans by causing intestinal illness.

Öomycetes

Diploid organisms known as 'water molds' that have cellulose cell walls, distinct from fungal chitinous walls, including the plant pathogen Phytophthora.

Excavata

A eukaryotic supergroup consisting of primitive organisms with complex cell shapes that often feature an excavate (surface depression).

Giardia lamblia

A flagellated Fornicata pathogen lacking mitochondria that causes diarrheal illness via fecal cyst contamination of water supplies.

Trichomonas vaginalis

A parabasalid pathogen possessing an undulating membrane and flagella that causes the sexually transmitted infection trichomoniasis.

Trypanosoma brucei

The causal agent of African trypanosomiasis (African sleeping sickness), transmitted by the bite of the tsetse fly.

Trypanosoma cruzi

The causal agent of American trypanosomiasis (Chagas disease), transmitted by Triatoma spp. ('kissing bugs').

Monoecious

Referring to organisms, including certain helminths, that possess both male and female reproductive organs within a single individual.

Dioecious

Referring to organisms, including certain helminths, where an individual possesses either male or female reproductive organs exclusively.

Nematoda

Unsegmented roundworms possessing a complete digestive system even when living as parasites.

Ascaris lumbricoides

The largest intestinal nematode parasite infecting humans, with adult females reaching lengths exceeding $1\,\text{meter}$.

Enterobius vermicularis

The pinworm, representing the most common nematode infection in the United States, which causes sleeplessness and perianal itching.

Trichinella spiralis

The nematode responsible for trichinellosis, contracted through undercooked meat whose released larvae encyst within host muscles.

Dirofilaria immitis

The filarial nematode transmitted by mosquitoes that causes heartworm disease in dogs and other animals.

Trematodes

Nonsegmented flatworms (flukes) possessing oral suckers used to adhere to internal walls of host organs, blood vessels, or intestines.

Schistosomiasis

A severe parasitic disease caused by Schistosoma flatworms associated with freshwater snails, ranking second only to malaria in impact on human populations.

Cestodes

Segmented flatworms (tapeworms) featuring an anterior scolex for attachment and body segments called proglottids.

Scolex

The specialized head region of a tapeworm outfitted with suckers or hooks to anchor against the small intestine wall.

Proglottids

Individual segmented units comprising a tapeworm body that contain reproductive structures and detach when gravid with eggs.

Oncosphere

The larval form that hatches from tapeworm eggs after ingestion by an intermediate host.

Cysticerci

Encysted larval forms that develop in intermediate host tissues following oncosphere migration, developing into adults when consumed by definitive hosts.

Diphylobothrium latum

The largest human tapeworm, contracted via undercooked fish, capable of growing to a length of $15\,\text{meters}$.

Mycoses

Infectious illnesses caused by fungi.

Hyphae

Microscopic cellular filaments that assemble to form multicellular fungal bodies (molds).

Mycelium

A tangled network of fungal hyphae that constitutes the thallus (body) of fleshy fungi.

Coenocytic Hyphae

Nonseptate fungal filaments that lack internal cross-walls and cell membranes between adjacent nuclei.

Pseudohypha

A short chain formed by budding yeast cells that fail to detach from one another.

Dimorphic Fungi

Fungi capable of alternating between mold and yeast morphologies depending on environmental cues such as temperature (e.g., mold at $25\,^\circ\text{C}$ and yeast at $37\,^\circ\text{C}$).

Ergosterols

Sterols located in fungal cell membranes that replace animal cholesterol and serve as prime targets for antifungal therapeutics.

Plasmogamy

The stage of fungal sexual reproduction in which the cytoplasms of $+$ and $-$ mating type gametes fuse to create a dikaryotic cell.

Karyogamy

The stage of fungal sexual reproduction in which the two nuclei of a dikaryotic cell fuse together to produce a diploid zygote.

Conidia

Asexually produced mitotic spores characteristic of various Ascomycota genera.

Aflatoxin

A metabolic byproduct of Aspergillus flavus that acts both as a potent toxin and as the most potent known natural carcinogen.

Dermatophytes

Pathogenic fungi belonging to Trichophyton, Microsporum, and Epidermophyton capable of triggering skin infections like ringworm, athlete's foot, and jock itch.

Basidiomycota

Fungi characterized by club-shaped basidia producing basidiospores through budding within basidiocarps.

Microsporidia

Unicellular obligate intracellular fungal parasites devoid of mitochondria, peroxisomes, and centrioles that deploy a polar tubule to penetrate host cell membranes.

Pyrenoids

Specialized subcompartments located within algal chloroplasts that synthesize and store starch.

Theca

A rigid, protective outer armor composed of cellulose plates found encasing certain dinoflagellates.

Frustules

Outer cell walls made of crystallized silica that enclose diatoms.

Holdfasts

Root-like anchorage structures used by multicellular brown algae (such as giant kelp) to adhere to solid substrates.

Lichen

A symbiotic partnership comprising a green alga or cyanobacterium and a fungus, functioning in a state of controlled parasitism.

Rhizines

Bundles of fungal hyphae used by lichens to anchor their thallus to the substrate.

Crustose Lichens

Morphological type of lichens that attach tightly to substrates, exhibiting a flattened, crusty appearance.

Foliose Lichens

Morphological type of lichens displaying leaf-like lobes, often attached at a single focal point, with a second lower cortex below the medulla.

Fruticose Lichens

Morphological type of lichens exhibiting cylindrical, rounded structures and an overall branched growth form.