4.6 Protists and Fungi Flashcards
Categorization of eukaryotes
- Excavata
- Stramenopiles
- Alveolata
- Rhizaria
- Amoebozoa
- Archaeplastida
- Opisthokonta
Excavata types
Diplomonads, Parabasalids, and Euglenozoa
Diplomonads
Posses mitochondrial genes in the cell nucleus as well as mitosomes
Anaerobic and acquire energy through glycolysis or other pathways
Giardia
Diplomonad intestinal parasite that is non-life-threatening and causes diarrhea
Mitosomes
Diplomonad intestinal parasite that is non-life-threatening and causes diarrhea
Parabasalids
Very large Golgi apparatus and associated cytoskeletal elements form a parabasal body
Contain highly modified mitochondria
Anaerobic
Produce hydrogen gas as a metabolic byproduct
Some colonize guts of ruminant animals and termites since they can digest cellulose
Trichomonas
Causes trichomoniasis, a sexually transmitted disease that causes vaginitis in females but is asymptomatic in males
Euglenozoans
Two major groups: euglenids and kinetoplastids
Include autotrophs, heterotrophs, mixotrophs, and parasites
Stiff pellicle cell membrane consists of microtubules that spiral around cell and connect to cytoskeleton
Euglenids
Type of Euglenozoan containing chloroplasts derived from secondary endosymbiosis
Kinetoplastids
Type of Euglenozoan containing kinetoplast consisting of large piece of DNA inside mitochondrion
Trypanosoma
Type of kinetoplastid transmitted by tsetse flies that causes African sleeping sickness
Leishmania
Type of kinetoplastid transmitted by sandflies that causes leishmaniasis
Cutaneous infection causes skin sores while visceral infection affects internal organs
Naegleria fowleri
“brain-eating amoeba”
Closely related to euglenozoans
Responsible for amoebic meningoencephalitis
Not a true amoeba but is an excavate with amoeboid and flagellate life stages
Lives in warm freshwater, typically ponds, lakes or reservoirs
Can infect humans by entering through the nose before migrating into the brain
Initially produces symptoms similar to meningitis but has a 95% fatality rate
Stramenopiles
Include brown algae, yellow algae, and diatoms
Heterokonts: flagella face different directions
Have two flagella, one short and smooth and one long and hairy
Some are photosynthetic with chloroplasts derived from red algae
Some are heterotrophic
Include slime nets and oomycetes which are plant pathogens
Alveolata
Groups: Apicomplexans, Dinoflagellates, Ciliates
Characterized by presence of alveoli which are membrane-bound sacs located beneath the cell membrane
Apicomplexans
Endoparasites containing an apical complex at one end of the cell consisting of a cluster of microtubules, vacuoles, and fibrin
Apical complex only present during certain stages of the life cycle and aids in the penetration and infection of a host
Include genera Plasmodium and Toxoplasma
Meiotic divisions occur after fertilization
Plasmodium
Type of apicomplexan
Transmitted by mosquitoes and causes malaria
Responsible for about half a million deaths per year
Toxoplasma
Type of apicomplexan
Prenatal infection can cause severe birth defects
Reason why pregnant women must avoid raw meat and cat litterboxes
Dinoflagellates
Posses two flagella oriented perpendicular to each other causing the entire organism to spin when moving
Many are photosynthetic and important primary producers in aquatic systems as a component of plankton
Some are bioluminescent
Blooms can produce a damaging “red tide” of chemicals poisonous to animals
Zooxanthellae
Type of dinoflagellate that form mutualism with stony corals
Ciliates
Posses rows of short cilia that form an undulating membrane used to create a current to ingest food into an oral groove
Contain two nuclei, one small micronucleus and one large macronucleus
Macronucleus functions in sexual reproduction
Macronucleus controls binary fission and non-reproductive functions such as metabolism
Rhizaria
Foraminifera and Radiolaria
Mostly marine amoebas with many long, slender pseudopods
Many produce tests
Pseudopod
Temporary extension of the cell that many microorganisms use to move or feed
Foraminifera
AKA forams
Produce multichambered tests from calcium carbonate and other materials
Some farm photosynthetic algae that harbor the tests
Use pseudopods to move, find food and find material to build tests
Very sensitive to changes in temperature making them useful indicator species of past and present climatic conditions
Sediments of dead forams form limestone or chalk after millions of years
Radiolarians
Create intricate glassy tests from silica
Capture prey using sticky axopodia
Component of plankton, sometimes living in colonial groups collecting symbiotic algae
Sediment of dead radiolarians decay and lithify over millions of years forming chert
Axopodia
Special type of pseudopod composed of an outer layer of cytoplasm supported by an inner core of cross-linked microtubules
Amoebozoa
Includes naked and testate amoebas
A few have large, multinucleated cells and some have multicellular stages
Move by extending their slender pseudopods and shifting their cytoplasm in the direction of movement.
Include slime molds, which share many similarities to fungi due to convergent evolution
Some alternate between haploid and diploid stages
Acanthamoeba
Amoebozoa found on unsanitized contact lenses that seriously damages the cornea of the eye
Archaeplastida
Arose from heterotrophic protist ancestor that acquired a chloroplast from an endosymbiotic event with a cyanobacterium
Includes glaucophytes, red algae, green algae, byrophytes, and vascular plants
Can be unicellular, multicellular, or colonial
Life cycles range from simple to complex
Glaucophytes
Small group of freshwater algae whose chloroplasts contain a layer of peptidoglycan
Rhodophytes
AKA red algae
Typically multicellular and along with two other subgroups of heterokonts and green algae, are considered seaweed or kelp
Photosynthetic
Get their name from red accessory pigments that cover up their green chloroplasts
Green algae
Divided into chlorophytes and charophytes
Closely related to land plants
Volvox
Chlorophyte that is a colonial organism
Exhibits cell specialization with only a few cells reproducing to create daughter cells
Ulva
AKA sea lettuce, a multicellular chlorophyte
Opisthokonta
Categorized by their single flagellum and flattened mitochondrial cristae
Includes unicellular protists including nucleariid amoebas, microsporidians, fungi, choanoflagellates, and animals (Metazoa)
Phagocytosis
Food particle is engulfed by a cell via a phagosome which then fuses with a lysosome to digest the food using hydrolytic enzymes
Phagosome
Food vacuole formed by pinching off a small amount of plasma membrane
Saprobes
Organisms that feed on dead organisms or organic waste products
Schizogony
Multiple fission that involves several nuclear divisions before the cells divide and can lead to the production of spores or sporozoites
Protists that can produce gametes through meosis
Ciliates, some flagellates, and amoebas
Conjugation (protists)
Two different mating types join by a cytoplasmic bridge
Diploid micronuclei undergo meiosis producing four daughter nuclei, three of which degrade, and then mitosis
Each cell transfers one of the two resulting nuclei to the other cell
The original macronucleus disintegrates, and the micronucleus and macronucleus are reconstructed
Bleaching
Coral losing pigment due to loss on zooxanthellae
Phytophthora infestans
Water mold that causes potato blight and led to the Irish potato famine which killed about one million people
Plasmodium falciparum cycle
Sporozoites are transmitted from mosquitos to humans
In the liver, they become schizonts and release merozoites that infect red blood cells
Parasites asexually reproduce in red blood cells, some undergo sexual reproduction as well
Gametes ingested by a mosquito where they form zygotes
Sporozoites formed in the oocysts burst out and migrate to the salivary gland
Encephalitozoon cuniculi
Microsporidian that infects the brain and kidneys and may cause neurodegenerative disease
Rare in humans but common in rabbits
Transmitted zoonotically through spores in the urine
Neocalllismastigomycetes
Fungi that obtained cellulases from bacteria
Can be found in the stomachs of animals including sheep, kangaroos, and elephants
Basidiomycetes
Named for reproductive structures, basidia, found in gills of their spore-forming fruiting body
Ascomycetes
Have similar life cycle to basidiomycetes
Many are asexual, including the single-celled yeast
Mycelium structure
Formed by branching hyphae
Hyphae form long chains
Individual hyphae are separated by porous cross-walls called septa
Septa allow the continuous flow of cytoplasm between cells
Coenocytic hyphae
Not separated by septa
Form large, multinucleated cells
Found in bread molds
Stages of sexual reproduction in fungi
Plasmogamy, karyogamy, and meiosis
1n –> 2n –> 1n
Plasmogamy
Stage of fungal sexual reproduction
Process of two cells fusing to bring together two haploid nuclei, producing a dikaryote
Can be very long for basidiomycetes, forming secondary mycelium and the basidiocarp
Some fungi use gametangia
Some have no gametangia and fuse hyphae to exchange nuclei
Karyogamy
Process of two haploid nuclei fusing to form a diploid nucleus
Gametangia
Sex organs in fungi that produce and release gametes or fuse to bring haploid nuclei together
Sexual reproduction in ascomycetes
Occurs within asci formed by the fusion of an ascogonium and antheridium
The nuclei in a dikaryotic ascus fuse, forming a diploid zygote
Zygote undergoes meiosis, mitosis, and cell division to form ascospores
Conidiophores release asexual spores called conidia
Ascocarp
Fruiting body of ascomycetes formed by the fusion of an ascogonium and antheridium
Conidiophores
Modified hyphae that release conidia
Sexual reproduction in basidiomycetes
Occurs withing the basidia on the basidiocarp
Mycelia of two different mating types come together to form a dikaryotic secondary mycelium
The secondary mycelium goes through mitosis and forms the basidiocarp and basidia
Nuclei of dikaryotic basidium fuse to form a diploid zygote
Zygote undergoes meiosis and divides to produce basidiospores
Lichen
Symbiotic relationship between fungi and algae
Dutch elm disease
Decimated elm population in North America and Europe
Caused by an ascomycete fungus transmitted by bark beetles
Blocks the tree’s xylem, reducing water conduction
