Chapter 12: The Eukaryotic Members of the Microbial World

Comprehensive vocabulary flashcards covering Chapter 12 lecture material on eukaryotic microbes, including fungi, algae, protozoans, and parasitic helminths.

Phytophthora infestans

A plant pathogen (water mold) that causes blight and was responsible for the Irish Potato Famine ($1845$-$1852$), resulting in an estimated $1.5\text{ million}$ deaths and $1\text{ million}$ people emigrating to the US and Canada.

Mycology

The scientific study of fungi, a kingdom of organisms that have existed on Earth for approximately $1.5\text{ billion}$ years.

Chitin

A tough structural component found in the cell walls of fungi, which is also uniquely present in the exoskeletons of insects.

Ergosterol

A unique lipid component of fungal plasma membranes that serves as an essential target for antifungal medications.

Hyphae

Thread-like multicellular filaments of molds through which nutrients are digested externally via secreted enzymes and then absorbed.

Fungal reproductive spores

Specialized reproductive cells released into the air from the tips of hyphae that enable molds to disperse and spread to new environments.

Mycelium

A tangled, spreading mass or vegetative network of branching hyphae that develops as a fungal spore germinates.

Budding

The asexual reproductive process characteristic of single-celled yeasts, distinguishing their growth pattern from multicellular molds.

Dimorphic fungi

Fungi capable of alternating their growth form between individual single yeast cells and multicellular molds depending on environmental conditions (e.g., Candida albicans).

Zygomycetes

A major fungal taxonomic group containing potential human pathogens, exemplified by Rhizopus stolonifer.

Rhizopus stolonifer

A Zygomycete mold commonly known as black bread mold; it is characterized by a black appearance and does not commonly cause disease in humans.

Ascomycetes

A fungal family comprising about $75\%$ of all known fungi, consisting of both molds and yeasts including Penicillium and Aspergillus flavus.

Penicillium

An Ascomycete fungus appearing blue/green or white on food that serves as an environmental decomposer and is used in cheese and antibiotic production.

Aspergillus flavus

An environmental Ascomycete mold that grows on many types of commercial grains and synthesizes dangerous aflatoxins.

Aflatoxins

Potent mycotoxins produced by Aspergillus flavus that cause severe animal disease and liver damage; their levels in commercial grains are monitored by the USDA.

Mycotoxins

Secondary fungal metabolites produced to fight competitors for food, capable of exerting toxic effects on bacteria, plants, animals, and humans.

Ergotamine

A toxic fungal mycotoxin that serves as the chemical precursor from which the recreational drug LSD (lysergic acid diethylamide) is synthesized.

Candida albicans

A dimorphic fungus and opportunistic human pathogen that normally inhabits the human body and can cause vaginal yeast infections and candidiasis.

Saccharomyces cerevisiae

An easy-to-grow, harmless single-celled yeast species designated as baker's and brewer's yeast, widely utilized in fermentation pathways and biotechnology.

Trichophyton rubrum

The fungal dermatophyte identified as the most common causative agent of Athlete's foot.

Ophiocordyceps

A genus of parasitic fungi that infects insects, chemically compelling them to climb to high ground on plants to optimize fungal spore dispersal.

Algae

Simple photosynthetic eukaryotes possessing chloroplasts and cell walls that do not directly cause infectious disease in humans.

Algin

A structural polysaccharide harvested from the cell walls of brown algae (kelp) used for commercial and industrial applications.

Diatoms

A group of simple photosynthetic eukaryotic algae distinguished by having unique, rigid cell walls composed of silica.

Diatomaceous earth

A sedimentary substance formed from accumulated deposits of fossilized diatom silica cell walls, used commercially for filtration and pest control.

Dinoflagellates

A diverse group of algae capable of bioluminescence (emitting a unique blue light), some species of which produce toxins harmful to humans during algal blooms.

Protozoans

Unicellular, 'animal-like' eukaryotic microorganisms that do not belong to the Animal Kingdom, historically classified by their locomotion using flagella, cilia, or pseudopods.

Trophozoite

The active, motile vegetative stage of a protozoan during which it feeds, grows, and reproduces.

Protozoan cyst

A dormant, highly resistant life stage that enables a protozoan to survive harsh environmental conditions and resist disinfection.

Conjugation (Protozoan)

A form of sexual genetic exchange in which certain protozoans temporarily unite to transfer or exchange DNA.

Bacterial endospores

Extremely durable dormant structures produced by bacteria that are more resistant to disinfection than protozoan cysts, requiring extreme heat and special chemical treatments to destroy.

Giardia lamblia

A flagellated protozoan causing waterborne diarrhea (giardiasis), spreading via the fecal-oral route through ingestion of contaminated freshwater cysts.

Trichomonas vaginalis

A pathogenic protozoan causing a sexually transmitted infection that does not form cysts, requiring direct transmission between hosts.

Trypanosoma brucei

A flagellated protozoan parasite transmitted to humans through the bite of an infected tsetse fly, causing African sleeping sickness.

African sleeping sickness

A vector-borne parasitic disease caused by Trypanosoma brucei that begins with fever and bite inflammation and can progress to a fatal coma as the parasite invades brain tissue.

Naegleria fowleri

A pathogenic freshwater amoeba known commonly as the 'brain-eating amoeba' that enters through the nasal passages during swimming to cause fatal brain infection.

Primary amoebic meningoencephalitis (PAM)

A rare but rapidly fatal central nervous system infection caused by Naegleria fowleri, typically presenting with crippling headaches.

Pseudopods

Temporary cytoplasmic extensions ('false feet') used by amebae for motility and feeding, functioning similarly to the movement of human white blood cells (macrophages and neutrophils).

Plasmodium falciparum

The eukaryotic protozoan parasite that causes the most common and deadly form of malaria, transmitted exclusively by blood-feeding female mosquitoes.

Malaria

A mosquito-borne parasitic disease affecting humans for $10{,}000\text{ years}$ in which Plasmodium destroys red blood cells, impairing oxygen transport across the body.

Doxycycline

An antimicrobial drug used to prevent Plasmodium falciparum invasion in travelers, which also kills prokaryotes by preventing bacteria from building proteins.

Communicable Disease Center (CDC)

The US government agency that played a major historical role in executing the National Malaria Eradication Program, wiping out domestic malaria in the early $1950\text{s}$.

Helminths

Large multicellular parasitic worms belonging to the Animal Kingdom that reproduce by producing microscopic eggs.

Flatworms

A group of parasitic helminths (such as tapeworms) characterized by flat, ribbon-shaped bodies and the complete absence of a digestive system.

Roundworms

A group of internally complex parasitic and free-living helminths featuring cylindrical bodies and a true digestive tract.

Scolex

The anterior head structure of a tapeworm equipped with specialized attachment organs to anchor the parasite to the host's intestinal wall.

Proglottids

Segmented body units of a tapeworm containing reproductive organs and eggs that detach and pass out in feces to transmit infection.

Enterobius vermicularis

A parasitic roundworm commonly known as the pinworm or 'butt worm' that causes enterobiasis, migrating to the anus at night to deposit eggs and induce intense itching.

Trichinella spiralis

A parasitic roundworm found in wild hog meat that causes trichinellosis, characterized by severe muscle cramping as larvae burrow into host muscle tissue.

Anisakis

A parasitic marine roundworm found in fish and undercooked seafood that causes severe intestinal pain when it attempts to penetrate the human gastrointestinal tract and dies.