Chapter 12: In Class Notes ( REVIEW)

This flashcard set covers key vocabulary and concepts related to fungi, algae, protozoa, and parasites as discussed in the lecture.

Fungi

Eukaryotic organisms with chitinous cell walls that absorb nutrients from their environment; typically reproduce via spores and lack chlorophyll.

Asexual Reproduction (Fungi)

Reproduction without gamete fusion; involves mitosis and formation of spores such as conidiospores or sporangiospores.

Sexual Reproduction (Fungi)

Involves the fusion of nuclei (plasmogamy → karyogamy → meiosis) to produce genetically diverse sexual spores.

Zygomycota

Fungi that form zygospores during sexual reproduction; typically have coenocytic hyphae.

Ascomycota

Sac fungi that form ascospores inside asci; includes many molds and yeasts.

Basidiomycota

Club fungi that form basidiospores on a basidium; includes mushrooms and puffballs.

Microsporidia

Unicellular, spore-forming fungi lacking mitochondria; obligate intracellular parasites.

Beneficial Effects of Fungi

• Production of antibiotics (e.g., penicillin)

• Used in fermentation (e.g., bread, alcohol)

Harmful Effects of Fungi

• Cause diseases (mycoses) in humans, animals, and plants

• Responsible for food spoilage

Lichens

Symbiotic organisms consisting of a fungus and a photosynthetic partner (alga or cyanobacterium); grow in nutrient-poor environments and rely on atmospheric sources for nutrients.

Fungus Role in Lichen

Provides structure, attachment, and moisture retention for the symbiotic organism.

Alga Role in Lichen

Conducts photosynthesis to produce carbohydrates shared with the fungal partner.

Algae

Mostly aquatic, photosynthetic eukaryotes with cellulose cell walls; can be unicellular or multicellular.

Chlorophyta

Green algae with chlorophyll a and b; closely related to plants.

Phaeophyta

Brown algae containing fucoxanthin; typically large and marine.

Rhodophyta

Red algae containing phycobiliproteins; contribute to reef formation and agar production.

Diatoms

Unicellular algae with silica cell walls; some produce the neurotoxin domoic acid.

Dinoflagellates

Algae with cellulose plates and two flagella; some species cause red tides and produce toxins.

Beneficial Effects of Algae

• Produce oxygen

• Serve as the base of aquatic food chains and are used in industrial applications (e.g., agar, alginates)

Harmful Effects of Algae

• Cause harmful algal blooms (HABs)

• Produce toxins that can harm marine life and humans

Protozoa

Unicellular, heterotrophic eukaryotes that usually lack cell walls and exhibit motility via cilia, flagella, or pseudopods.

Amoebozoa

Move using pseudopodia; includes Entamoeba histolytica, a cause of amoebic dysentery.

Apicomplexa

Non-motile, obligate intracellular parasites; includes Plasmodium, which causes malaria.

Ciliophora

Protozoa that move and feed using cilia; includes Paramecium.

Euglenozoa

Protozoa with flagella; includes both photosynthetic organisms (e.g., Euglena) and parasites (e.g., Trypanosoma).

Archaezoa

Flagellated protozoa lacking mitochondria; includes Giardia lamblia.

Parabasala

Flagellated protozoa with undulating membranes; includes Trichomonas vaginalis.

Diplomonads

Protozoa with two nuclei and multiple flagella; includes Giardia.

Intermediate Host

A host that harbors the larval or asexual stage of a parasite.

Definitive Host

A host that harbors the adult or sexually mature stage of a parasite.

Cellular Slime Molds

Exist as individual amoeboid cells that aggregate to form a fruiting body during reproduction.

Plasmodial Slime Molds

Exist as a multinucleated mass (plasmodium) that moves as one entity and forms spores when environmental conditions change.

Parasitic Helminths

Multicellular parasitic worms with reduced digestive and nervous systems and complex reproductive cycles involving one or more hosts.

Life Cycle of Parasitic Worms

Involves multiple hosts and developmental stages to increase survival, reproduction, and transmission.

Trematodes (Flukes)

Flat, leaf-shaped parasitic worms with suckers for attachment; example: Schistosoma.

Cestodes (Tapeworms)

Segmented flatworms with no digestive system; absorb nutrients through their surface. Example: Taenia.

Parasitic Infection: Human as Definitive Host

Example: Taenia — adult tapeworm resides in human intestines.

Parasitic Infection: Human as Intermediate Host

Example: Echinococcus — human harbors larval cyst stage.

Parasitic Infection: Human as Both Hosts

Example: Schistosoma — human supports both immature and adult stages.

Parasitic Nematodes

Roundworms with complete digestive systems and non-segmented bodies; reproduce sexually.

Infective eggs (Nematodes)

Example: Ascaris lumbricoides

Infective larvae (Nematodes)

Example: Necator americanus

Platyhelminths vs. Nematodes

• Platyhelminths: flat-bodied; often have incomplete digestive systems; typically hermaphroditic.

• Nematodes: cylindrical; have complete digestive systems; sexes are separate.

Arthropod Vector

An invertebrate animal (e.g., insect or arachnid) that transmits pathogens to other organisms either mechanically or biologically.

Tick

Arachnid vector; transmits Borrelia burgdorferi, which causes Lyme disease.

Mosquito

Insect vector; transmits Plasmodium spp., the causative agent of malaria.

Identification of Fungi vs. Bacteria

A fungus differs from a bacterium by being eukaryotic, possessing a nucleus, membrane-bound organelles, and a cell wall composed of chitin rather than peptidoglycan.

Sexual vs. Asexual Spore Formation (Fungi)

• Asexual spores: form by mitosis without nuclear fusion, producing genetically identical offspring.

• Sexual spores: form following plasmogamy, karyogamy, and meiosis, resulting in genetic recombination.

Spores of Major Fungal Phyla

• Zygomycetes: Asexual spores: sporangiospores; Sexual spores: zygospores.

• Ascomycetes: Asexual spores: conidiospores; Sexual spores: ascospores.

• Basidiomycetes: Asexual spores: occasionally conidiospores; Sexual spores: basidiospores.

Microsporidia Classification as Fungi

Classified as fungi because they are eukaryotic, form spores, and are closely related genetically to fungi, despite lacking mitochondria and being obligate intracellular parasites.

Yeasts: Beneficial or Harmful

Yeasts can be beneficial (used in fermentation and baking) or harmful (cause infections such as candidiasis).

Role of Lichens in Nature

Lichens contribute to soil formation, serve as environmental indicators, and participate in nutrient cycling by fixing carbon.

Role of Fungus in a Lichen

Provides structure, protection, and moisture retention, allowing the photosynthetic partner to survive in harsh environments.

Differences Between Algae and Bacteria

Algae are eukaryotic, have a nucleus, and carry out photosynthesis using chloroplasts. Bacteria are prokaryotic, lack a nucleus, and perform photosynthesis (if any) using membrane-bound pigments.

Differences Between Algae and Fungi

Algae are autotrophic and contain chlorophyll. Fungi are heterotrophic and lack chlorophyll.

Algal Cell Wall Composition and Associated Diseases

• Diatoms: silica cell walls; produce domoic acid poisoning.

• Dinoflagellates: cellulose plates; cause paralytic shellfish poisoning (PSP) via neurotoxins.

• Oomycotes: cellulose cell walls; cause plant diseases like Phytophthora infestans (potato blight).

Differences Between Protozoa and Animals

• Protozoa are unicellular, animals are multicellular.

• Protozoa often reproduce asexually; animals reproduce sexually.

• Protozoa may have distinctive locomotion organelles (cilia, flagella, pseudopodia) not found in most animal cells.

Mitochondria in Protozoa

Most protozoa have mitochondria, though some anaerobic species (e.g., Giardia, Trichomonas) lack them.

Site of Sexual Reproduction in Plasmodium

Sexual reproduction occurs in the mosquito vector (Anopheles), which is the definitive host.

Slime Molds Classified with Amebae

Classified with amebae because they move and feed by phagocytosis and lack cell walls during most of their life cycle, unlike fungi.

Toxicity of Helminth Drugs

Antiparasitic drugs are often toxic to hosts because helminths are eukaryotic, sharing many biochemical pathways with human cells.

Value of Complex Life Cycles in Helminths

Increases transmission opportunities, ensures completion of development in suitable hosts, and helps evade host immune defenses.

Difference Between Paragonimus and Taenia

• Paragonimus: trematode (fluke) that infects the lungs.

• Taenia: cestode (tapeworm) that inhabits the intestine.

Definitive Host for Enterobius

Humans serve as the definitive host for Enterobius vermicularis (pinworm).

Infectious Stage of Dirofilaria immitis

The larval stage (L3) transmitted by a mosquito is infectious for dogs and cats.

Identifying a Worm: Taenia vs. Necator

• Taenia (tapeworm): flat, segmented, visible proglottids.

• Necator (hookworm): cylindrical, unsegmented, with a visible mouth capsule or hook-like structures.

Three Types of Arthropod Vectors and Diseases

• Mechanical vector: carries pathogens externally (e.g., housefly → Salmonella).

• Biological vector: pathogen develops inside vector (e.g., mosquito → Plasmodium).

• Reservoir vector: maintains pathogen long-term (e.g., tick → Borrelia burgdorferi).

Identifying a Tick vs. a Flea

• Tick: arachnid; 8 legs, flat body, lacks wings, slow-moving.

• Flea: insect; 6 legs, laterally flattened body, wingless but highly jumping.