lab 6: heterotrophic protists & fungi

Question 1

protists

Answer 1

a group of organisms that includes all eukaryotes but land plants, fungi, & animals

Question 2

protozoans

Answer 2

-among the most versatile of all organisms on Earth (found in a drop of pond water to the intestines of termites)
-eukaryotes
-heterotrophic (have food vacuoles to enclose food particles for digestion)
-contractile vacuoles to expel excess water

Question 3

how protists reproduce?

Answer 3

-sexual reproduction: offspring is genetically different from parents
-asexual reproduction: offspring is genetically identical to parents
-most protists go through asexual reproduction but many go through sexual reproduction only intermittently
-the evolution of sexual reproduction ranks among the most significant evolutionary innovations observed in eukaryotes

Question 4

protists can cause disease

Answer 4

-the phytophtora infestans caused the Irish potato famine
-about a million people died
-many emigrated to escape famine

Question 5

supergroup amoebozoa: amoeba

Answer 5

-they have pseudopods (movable extensions of cytoplasm) used for locomotion & gathering food
-they don’t have flagella
-they don’t have a cell wall
-they engulf their food (phagocytic)
-they are a polyphyletic group (they don’t include a common ancestor)
-reproduce asexually
-have this food vacuole which they’ll secrete some enzymes for intracellular (inside) digestion
-some have a contractile vacuole which maintains the cell’s water balance & gets rid of any excess water
-difflugia make a protective covering of sand grains called a test
-chaos

Question 6

supergroup rhizaria: foraminiferans

Answer 6

-they can be used to help locate oil bearing strata (help locate where oil is)
-very old
-can take a rock sample & there will be specific rhizaria that are found with oil anyways
-shelled amoebas; they have a calcium carbonate test, porous (lets them go in & out)
-long, thin & stiff pseudopods
-great fossils (can accurately date rocks)

Question 7

supergroup excavata: flagellates

Answer 7

-euglena
-have at least one flagella (used for locomotion)
-can be parasitic or free living heterotrophs
-some can cause disease like the trypanosoma (causes the African sleeping sickness; transmitted by the tse tse fly & chagas disease; transmitted by assassin bug)

Question 8

what causes African sleeping sickness? - might be on quiz

Answer 8

trypanosoma

Question 9

supergroup chromalveolata: ciliates

Answer 9

-named for the cilia that covers them, & which they use for locomotion & gathering food
-cilia & flagella are both extensions of plasma membranes
-with flagella there might be 1 or 2 long ones
-with cilia there is a lot of short extensions
-brown algae is also in this supergroup
-they have 2 nuclei: micronuceli & macronuclei
-micronuceli is said to be leftover cytoplasm
-macronuceli controls cell function
-can reproduce asexually or by conjugation (sexually)
-can be filter feeders, predators, or parasites
-have a gullet area (mouth area) where they ingest food
-abundant
-can live mutualistically in the guts of many grazing animals (cows)

Question 10

paramecium: ciliates

Answer 10

-free-living freshwater genus
-can reproduce sexually by conjugation (two individuals align & exchange nuclear material)
-more commonly through asexual reproduction by transverse fission

Question 11

vorticella: ciliates

Answer 11

-freshwater
-sessile (attached to something/substrate)
-have a contractile stalk helps them to filter feed (get away from their substrate a little bit)
-have a cell body with corona of cilia for filter feeding
-stentor (example): heterotrophic & binary fission

Question 12

supergroup chromolaveolata: apicomplexans

Answer 12

-parasites of animals
-genus plasmodium responsible for malaria
-absorb nutrients directly from their host
lack cilia & flagella; can move by this amoeboid motion
-reproduce sexually or asexually

Question 13

malaria

Answer 13

-the world’s most chronic public health problem caused by a parasitic protist called plasmodium malariae
-over a million fatalities a year
-300 million infected
-a lot of kids
-are other human health problems that are caused by protists, including amoebic dysentery & trichomoniasis but malaria is a big one

Question 14

supergroup amoebozoa: slime molds

Answer 14

-fungus-like but they don’t have enough to be classified as a fungus
-have amoeboid characteristics like:
-phagocytic nutrition & unique unicellular forms
-lack hyphae of fungi
-do not contain chitin as fungus do
-protists
-also called a plasmodium: when individual cells are indistinguishable
-contain diploid nuclei (considered multinucleate: nuclei are not separated by a cell wall)
-during unfavorable conditions, they can dry up (phase called dormancy phase which is called sclerotium)
-when they can find food, the amoeba can form this stalk topped by a ball-like structure
-important decomposers in forests

Question 15

fungi

Answer 15

-range from cute to gross
-some are edible to poisonous
-cures to disease
-decomposers (FBI: fungi, bacteria, invertebrates)
-pests
-poorly understood
-simple bodies: 2 growth forms: single celled forms (yeast); multicellular filamentous forms (mycelia)
-some fungi adopt both forms

Question 16

mycelium & hyphae

Answer 16

-hyphae: basic structure of a fungus
-slender filament of cytoplasm & nuclei enclosed by cell wall
-mass of hyphae is called a mycelium
-mycelium secrete the enzymes for extracellular digestion (absorptive heterotrophs)
-some fungi are parasitic

Question 17

septa, coenocytic, & haustoria

Answer 17

-hyphae are separated into compartments by cross-walls called septa
-septa is made up of chitin (same polysaccharide found in exoskeleton of insects & crustaceans)
-gaps in septa are called pores
-some are multinucleate (coenocytic) can lack septa entirely (aseptate)
-some hyphae will have haustoria (really thin, allow the hyphae to reach other parts of the plant that the fungi couldn’t otherwise; can penetrate tiny crevices in soil & absorb nutrients that other mycelia can’t

Question 18

saprophytes

Answer 18

-make their living by digesting dead plant material
-fungi are saprophytes
-included in the carbon cycle that has 2 basic components
1. fixation of carbon by land plants
2. the release of CO2 from plants, animals, & fungi as the result of cellular respiration
-fungi connect these 2 components as they are the organisms that break down complex molecules in wood into reusable organic compounds

Question 19

extracellular digestion

Answer 19

-synthesize enzymes & secrete them outside their hyphae into their food
-food is then absorbed
-fungi are absorptive heterotrophs
-fungi feeding on living organisms = parasitic

Question 20

variation in reproduction

Answer 20

-asexual: spores, budding, fragmentation
-sexual: fungi may produce swimming gametes & spores, hyphae will be yolked together which will form a zygote inside different protective structures based off their name

Question 21

asexual reproduction

Answer 21

-spores: mitotic production of haploid cells produced in sporangia & conidiophores (both are the same thing)
-budding: mitosis followed by an uneven distribution of cytoplasm (grows out & attaches & gets picked up by a parent plant)
-fragmentation: breaking off & growing into new organism

Question 22

sexual reproduction

Answer 22

-haploid cells (n) from 2 mating strains fuse their cytoplasms (plasmogamy) & becomes dikaryotic (n + n) with 2 nuclei per cell [not diploid (2n); bc only fusing cytoplasm not nuclei]
-then the nuclei fuse via a process called karyogamy to become diploid (2n) zygotes
-karyogamy is equal to fertilization
-gametes are produced from mitosis not meiosis

Question 23

phylogeny

Answer 23

-fungi have 5 types of distinctive reproductive structures on which their phylogeny is based:
1. chytridiomycota- both the sexually produced gametes & asexually produced spores in the chytrids have flagella & are the only known motile fungal cells
2. zygomycota- the zygomycetes have zygosporangia, formed when cells from 2 yoked-together haploid hyphae fuse
3. basidiomycota- basidia are specialized spore-producing cells that form at the ends of basidiomycetes hyphae
4. ascomycota- asci are sac-like spore-producing cells that form at the end of ascomycetes hyphae
5. glomeromycota- known for their symbiotic relationships with plant roots
- 1 & 2 are paraphyletic (a single common ancestor didn’t give rise to all species within each phylum)

Question 24

phylum: chytridiomycota (chytrids)

Answer 24

-chytrids are largely aquatic & are common in freshwater environments
-members of this group are the only fungi that can produce motile cells
-most chytrid species produce spores that swim to new habitats via a flagellum
-many chytrids can digest cellulose & have lifestyles ranging from decomposers to parasites to mutualists
-a chytridid fungus is thought to be linked to amphibian declines

Question 25

phylum: zygomycota (bread molds)

Answer 25

-primarily soil dwellers
-their hyphae yoke together & fuse during sexual reproduction & then form a durable, thick-walled zygosporangium
-many are saprophytes (feeding on dead/decaying matter), some are parasitic, & some are predatory
-species include the common bread mold as well as lineages that cause rot in fruit & vegetables

Question 26

rhizopus: bread mold

Answer 26

-common black bread mold
-hyphae modified to rhizoids (holdfasts), stolons (connecting hyphae) & sporangiophores (asexual reproductive structures)
-sporangiophores (upright hyphal filaments) support asexual reproducing sporangia
-within sporangium haploid nuclei become spores & are separated by cell walls
-spores are released upon maturity
-isogamous (+ & - strains)
-strains grow towards each other & form gametangia (reproductive structures)

Question 27

Phylum ascomycota (sac fungi)

Answer 27

-monophyletic & most highly derived group of fungi besides basidiomycota
-30,000 species (yeasts, molds, morels & truffles)
-sac-shaped reproductive structures called an ascus
-reproductive asexually by forming spores called conidia
-modified hyphae called conidiophores partition nuclei in longitudinal chains of breadlike conidia
-each conidia contains one or more nuclei (monokaryotic & dikaryotic)
-over half of all known fungi belong to the ascomycota

Question 28

phylum basidiomycota (club fungi)

Answer 28

-monophyletic & most highly derived group of fungi besides ascomycota
-looks like the mushroom from Mario Kart
-25,000 species (mushrooms, puffballs, shelf fungi, rusts & smuts)
-the entire array of absorptive lifestyles found in fungi (saprophytic, mutualistic & parasitic)
-species are important as food sources, biological research
-during sexual reproduction, all basidiomycetes produce basidia
-basidiocarp form a cap & gills
-basidia form on the surface of gills
-the largest subgroup forms basidia in large, aboveground mushrooms, brackets, earthstars or puffballs
-asexual reproduction is less common than in other fungal lineages

Question 29

aspergillus

Answer 29

-some species of this genus are responsible for human lung infections
-other species of aspergillus produce the highly toxic aflatoxin, which can be fatal at certain doses & is suspected to be a powerful carcinogen in birds & mammals (including humans)
-has hyphae with spores of a different color

Question 30

penicillium

Answer 30

-the process for producing penicillin & blue cheese both use the penicillium fungus
-penicillium is the mold from which the first known antibiotic was isolated. it grows abundantly & produces colored spores

Question 31

ophiocordyceps fungi

Answer 31

-the kind of fungi that infects insects
-causes them to act erratically
-in the last of us (video game & show)

Question 32

lichens

Answer 32

-ascomycetes grow in symbiosis with photosynthesis algae (protists) or cyanobacterium
-fungal hyphae form a dense protective layer that shields the photosynthetic species & reduces water loss
-in return the cyanobacterium or algae provides carbohydrates that move from photosynthetic species to fungus
-the fungus uses it as a source of carbon & energy
-the fungus does not eat the algae/cyanobacteria - that would be parasitism
-many lichens reproduce asexually

Question 33

phylum: glomeromycota

Answer 33

-plant root synthesis
-symbiotic relationship with plant roots
-fungi are called mycorrhizae
-extensions of roots systems
-immense biomass
-provide 20% of the plants carbon as carbohydrates
-absorb nitrogen & nutrients for 90% of plant species
-abuscular mycorrhizae penetrate plant root cells & closely contact root cells called plasma membrane
-ectomycorrhizae are basidiomycetes & extend between the host root cells but don’t penetrate the cell wall