Protozoa And fungi Flashcards
Slime molds belong to which phyla
Water molds belong to which phyla
Which kingdom do they belong to
Myxomycota
Oomycota
Protozoa-little evidence for direct relationship to fungi.
Class myxomycetes are known as
Plasmodial slime molds
Plasmodial slime molds characteristics
-many diploid nuclei not divided by cell walls
-as it grows, nuclei divide repeatedly and synchronously
-thin streaming masses of protoplasm that creep along in an Amoeboid fashion
Feeding of Plasmodial slime molds
-engulf by phagocytosis bacteria, yeast cells, fungal spores and small particles of decayed plant and animals matter
How do Plasmodial slime models move
Cytoplasmic streaming
The cytoplasm can be seen to stream outward towards the edge of the plasmodia then slowed stop and stream onwards. This cycle alternated in different veins and the whole cycle repeated once every 3-5 min
Plasmodial growth continues as long as…..
What happened if it is not….
There is adequate food supply and moisture available
Plasmodium migrated to an exposed area and enters its reproductive stage when food and moisture are lacking.
Under adverse conditions, the plasmodium will produce fruitifications
What happens in fruitifications or fruiting bodies
Meiosis occurs to produce haploid spores.
Meiospores have cell walls that contain cellulose.
Myxomycota have what 3 reproductive structure types
Sporangium
Aethalium
Plasmodiocarp
Sporangium of Myxomycota
In many species, when the plasmodium stops moving, it divided into a large number of small mounds. Each mound produces a mature sporangium, usually borne at the tip of a stalk.
Peridium
A wall that encloses the spore mass
-may vary from delicate, thin and membranous to thick and tough impregnated with lime or refuse matter
Part of sporangium
Stalk or stipe of sporangium
Unless the fruiting body is sessile, it it borne by the stalk. Stalks display a diverse range of lengths, thicknesses and colours
Hypothallus of sporangium
A layer deposited by the plasmodium at the base of one or more of the fruiting bodies. Often it is continuous under a colony or cluster of sporangia; at other times it forms veins connecting a few fruitions bodies
Columella of sporangium
Located at the Center or at the base inside the sporangia. It appears to be an extension of the stalk, and may serve to support the spore mass
Capillitium of sporangium
Extensive series of thread-like structures usually present among the spores. These threads are sensitive to changes in humidity and expand and contract, helping to release the spores
Spores of sporangium
Very large number of haploid spores are produced in each fruiting body
Aethalium
Relatively massive, single chambered, sporangiophores. They are thought to have been formed by complete fusion of large numbers of sporangia during their evolutionary development. No trace of individual sporangial walls are found in most Aethalia
No stalks
No insidiously capitula
Plasmodiocarp
Discrete sporangia or aethalia are not produced. Instead, the entire plasmodium may develop into a Plasmodiocarp, which retains the former shape of the plasmodium
Spores of Myxomycota
Very small and easily dispersed by the wind
-if they land in favourable habitat they germinate.
-protoplasm may remain Amoeboid or it may develop one or two whiplash flagella.
Amoeboid is interchangeable with
Flagellated Swarm cells
Amoeboid feeding and multiplying
Ingestion of bacteria and organic material and multiple by mitosis and cell cleavage
If the food supply is used up, or conditions are otherwise unfavourable, the amoebae may cease to move and …..
Become round and secrete a thin wall to form a Microcyst
Microcysts can remain viable for a year or more, resuming activity when favourable conditions return
After a period of growth, plasmodia are formed by……
The fusion of gametes which are usually genetically different from one another and are derived from different haploid spores.
Gametes are amoebae or flagellate cells playing a new role
Oomycota are known as
Water molds or downy mildews
The members of phyla oomycota all produce ……
Nonsexual propagative spores that are flagellate (zoospores) and the number, position and type of flagellae provide the means for further breakdown. They do not generate any complex spore-producing organs.
Thalli of oomycota
Relatively simple, ranging from a single cell, which is eventually converted into a reproductive structure (holocarpic) to a differentiated cells which is separated into a veg active and reproductive portion.
Most complex thallus is a branched coenocytic mycelium.
Where do oomycota live
Water or at least require free water for a motile flagellate stage
How are oomycota distinguished from chytrids
Exclusively diploid assimilative hyphae
-cell walls of these organisms are composed largely of cellulose or cellulose-like polymers, thus differing markedly from the cell walls of the fungi which are made of chitin. They range from unicellular formed to highly branched, coenocytic filamentous ones
How do oomycota reproduce
Both sexually and asexually
Sexual is Oogamous (egg is large and non motile and Sperm is small and biflagellate). Union results in an oospore, which serves as a resting spore.
Asexual is by zoospores that have 2 flagella: one tinsel and one whiplash
Order Saproleginales habitat and lifestyle
Aquatic oomycota
-water molds
-fresh water
-saprobic, few are parasitic
Sexual reproduction in water molds can occur with male and female sec organs borne on the same individual =
Or
Male and female sex organs are borne on different individuals
Homothallic - Saproleginales
Heterothallic - Achlya
Both Saprolegina and Achyla reproduce ……
Both sexually and asexually
Order Peronosporales habitat and lifestyle
Primarily terrestrial oomycota
Pathogen - plasmopara viticola caused downy mildew on grapes and Phytophthora infestans cases late blight on potatoes
Order Saproleginales (water molds)
Structure
-profusely-branched coencytic hyphae which forms a colony around decaying organic material in the water
-diploid mycelia
Saprolegnia sp.
-lifestyle
-reproduction is mainly
-Parasitic on fresh water fish and fish eggs
-asexual
Asexual and sexual cycle of Saprolegnia
Asexual: tips of vegatatice hyphae have sporangia which undergo mitosis to produce flagellated primary zoospores. These encyst and then form secondary zoospores, which then encyst and then became vegetative hyphae
Sexual: vegetative hyphae have Oogonia on tips. Undergo meiosis to produce oospheres. Antheridia develops from other tips of same inddivual to produce nervous male nuclei. Antheridia grow toward Oogonia and develop tubular processes called fertilization tubes, that penetrate the Oogonia. Male nuclei travel down fertilization tubes to the female nuclei and fuse with them. Thick walled zygote (oospore) is produced. Upon germination, the oospore developed into a hyphae which then produced a sporangium.
Homothallic (monoecious)
Order Peronosporales (downy mildews)
-lifestyle
-reproduction stages
-obligate parasite on the aerial parts of higher plants
-spores are wind borne, sporangia are not unspecialized hyphae tips, but borne on branched aerial asexual conidiophores, which produce asexual spores called gonidia.
-sexual sporangia are borne on sporangiophores. The sporangiophores cover the surface of the leaves and stems of the infected plants, giving them a downy appearance. The entire sporangia are released, then fall to the ground to be picked up by emerging seedlings or are carried on the wind to and on leaves of more mature plants.
-if free water is present, the sporangia germinate and release flagellated zoospores. These zoospores swim and enter the plant tissue through open stomata, or any break in the cuticle. The zoospores then Develop into the hyphae which invaded the host tissue.
The mycelia of Peronosporales feed ok living cells by the use of
Haustoria
Haustoria penetrate the living host cells and absorb nutrients and pass them to the growing hyphae
Peronospora parasitica
Downy mildew on crucifers
-organism causes infections in mustard, canola, broccoli, cabbage, cauliflower and turnips
-diseased plants are detected by their swollen, and distorted stems bearing a white flower or sporangiophores.
-the leaves the fungus is associated with a yellowish patch on the upper surface and the formation of white sporangiophores beneath.
-invading mycelia destroy the host tissue.
Downy mildews do not occur in the _____ habitat and the motile zoospore stage is all but _______ in Peronopsora
Aquatic
Absent
Phytophthora infestans
Late blight on potatoes
-caused by a fungus-like organism called Phytophthora infestans which is a destructive parasite of potatoes
In potatoes the disease can cause rapid destruction of foliage and tubers.
Is Phytophthora infestans Homothallic or heterothallic
Heterothallic, requiring presence of two different strains for sexual reproduction to occcur
Whether a strain will be male or female is under nutritional control.
asexual reproduction of Phytophthora infestans
Highly efficient and can result in rapid infestation of crops.
How does Phytophthora infestans work
Branched sporangia emerge from the leaves, commonly through the stomata, and hygroscopic twisting of the sporangiophore occurs with changes in humidity, flicking off the sporangia into the wind. When wind-borne sporangia land on a moist leaf surface, they germinate by production of germ-tubes or at cooler temps by production of motile zoospores that may be dispersed further by swimming and splashing.
-infection of new host plant may take place inside 2 hours and production of new sporangia are sensitive to drying.
Spells of ___________ price the rapid spread and crop destruction in Irish famines of Phytophthora infestans
Cool, damp weather
Symptoms of Phytophthora infestans
dark lesions on stems or leaves resembling those caused by frost.
-under moist conditions: whitish masses of sporangia appear on the lesions.
-the tubers develop brown or purple blotches on skin, which spreads into the tuber flesh. Late blight can be a rapid and destructive disease: fields appear to be healthy but contain low incidence of disease, can be devastated within days
Most fungi are multicellular filamentous structures, but yeasts are
UnicellulR
Hyphae
Mycelium
Fungal filament
Mass of hyphae from one organism
Septae
Cross walls of fungal hyphae
Septate
Aseptate or coenocytic
Hyphae with cross walls
Hyphae lacking cross walls
Functionally coenocytic
Even in hyphae with septae, there is movement of materials through a central pore in each septum. Protoplasm and nuclei can move from cell to cell making them functionally coenocytic
Ascomycota Intraseptal pores
Large enough to accommodate passage of nuclei from cell to cell.
Nuclei of fungal hyphae are _____
Haploid
All fungi have cell walls composed primarily of
Primary storage polysaccharide in fungi
Polysaccharide chitin
Glycogen
Rhizoids
Specialized hyphae to anchor some types of fungi to substrate
Haustoria
Specialized hyphae of parasitic fungi which penetrate the plasma membrane of other organisms also that the fungus can absorb directly the cell contents of the host
Fungi reproduce through the formation of either _________ spores
Most fungi have _____ spores but chytrids are an exception
Sexual or asexual
Non-motile
Asexual reproduction in fungi is most commonly by ____ formation, with spores either produced in _______ or as single cells or chains of spores in ______ which arise from _____.
In some fungi, the hyphae can reproduce asexually via _______
Spore
Sporangia
Conidia
Hyphae
Fragmentation
Fungal sexual reproduction consists of what phases
Plasmogamy-fusion of protoplasts
Karyogamy - fusion of nuclei
Meiosis
Dikaryon
Two nuclei
The fusion of nuclei does not necessarily follow immediately after plasmogamy and hence the two haploid nuclei can exist together, unfused.
If Karyogamy is delayed long enough, the paired haploid nuclei each may…..
Begin to divid mitotically and produce a dikaryotic mycelium. The haploid nuclei with eventually fuse within a fruiting body to form a diploid nucleus which quickly exhibits Zygotic meiosis and the only diploid phase in the life cycle is the zygote
Members of zygomycota produce ______ as their sexual reproductive spores
Zygospores
Heavy-Walled zygote not associated with an oogonium.
Ascomycota produce ________ within a special structure termed an ______
Ascospores
Ascus
Baidiomycota produce _______ in a ______
Basidiospores
Basidium
Phylum Chytridomycota or chytrids
Habitat and lifestyle
Mainly aquatic but some live in damp soil
Many are Parasitic on algae, fungi, mosses and higher plants
Chytrids cell walls composition
Mostly of chitin
Zoospores and gametes of chytrids have
-one posterior whiplash flagella at maturity.
Likely they branched off from other fungal lines and their flagellates condition represents the retention of primitive characteristic destined from a flagellated protist ancestor.
Chytrids consist of forms with no true ___ and most are ______
Mycelium
Coenocytic
During reproduction, what do chytrids do
Whole organism is transformed into a reproductive unit
Synchytrium endobioticum
-what phyla
-common name
Chytriomycota
Black wart disease of potato
Synchytrium endobioticum
Obligate parasite which causes black wart disease of potatoes. Like many other specialized parasites it induces abnormal growth (hypertrophy) of infected cells. The infested tubers have large-wart like growth on them. Although there have been bad outbreaks of this disease in Newfoundland, it is not of economic importance today due to the strict control over the import of infected seed potatoes.
Produced thick walled resting spores in the wafted tuber. Also formed zoospores which have a very short range of operation in the aqueous phase of soil.
Synchytrium endobioticum is ______ and ________ (whole cell becomes reproduce structure)
Unicellular
Holocarpic
Only member of the Fungi in which motility have been retained
Order Blastocladiales
Blastocladiomycetes tend to be ______, in which there is an extensive vegetative growth habit in which some of the organism participated in reproduction (sexual or sexual)
Eucarpuc
Members of _______ exhibit complete alternation of generations between a haploid gametophyte and a diploid sporophyte
Blastocladiales
Allomyces forms a ______ in both generations
Cottony mycelia
Gametophytes of allomycetes
Tandem paired gametangia that terminate the hyphae such that the terminal gametangia (usually smaller of the two) is male and it produces the smaller of the two motile ansiogametes. The larger proximal gametangia release larger motile ansiogametes.
Sporophyte of Allomyces
Produced terminal single sporangia within which meiosis occurs and zoospores are formed
Released zoospores develop into gametophyte
Allomyces sp.
-habitat
-alternation of generations?
-Water mold distributed in soil throughout the world and particularly in warmer climates
-yes, diploid filamentous sporothallus produces spores and a haploid filamentous gametothallus produces gametes
The filamentous cells of Allomyces grow without ……, and divide in a _________
Limitation in length
Dichotomous pattern that results in a geometric mycelium
Hyphae of Allomyces
Hyphae are separated by pseudosepta that allow free circulation of intracellular materials along the filaments.
The reproductive structures at the end of hyphae are isolated by compete septa.
Allomyces macrogynus is a ______ fungi which exhibits two very similar looking dichotomously branching coenocytic thallus while immature. However, once thalli have reached maturity…..
Saprobic homothallic
-orange male gametangia growing Epigynously on the clear female gametangia make the haploid gameothallus differentiator from the diploid sporothallus that produces terminal sporangia.
Gametangia of Allomyces produce what
Small haploid posterior, uniflagellate gametes.
The female gametes is much less motile than male and diffuses a hormone to attract the male gamete. Upon gamete fusion, a large posterior biflagellate zygote is produced that encyst to form the sporothallus
On a single sporothallus of Allomyces, what can be produced
Pigmented resistant sporangia and clear zoosporangia
Thick-Walled melanin pigments resistant sporangia are the site of meiosis and release haploid zoospores into an exit papilla prior to release into the water.
Haploid zoospores later encyst to form the gametothallus
Phylum Zygomycota
-lifestyle
Saprobic-living on decaying plant or animal material in the soil. Some may be parasites on plants, insects or small soil animals.
Rhizopus stolonifera
-common name
-what does it cause
Bread mold
Causes black bread mold that forms cottony masses on the surface of moist bread exposed to the air.
Mycelium of Rhizopus stolonifera
Composted if 3 different types of haploid hyphae
-bulk of mycelium consists of rapidly growing hyphae that are coenocytic and aseptate. Arching hyphae called stolons are formed. Stolons form this puts wherever their tips come in contact with the substrate.
Sporangia of Rhizopus stolonifera
Form on the tips of sporangiophores, which are erect branched formed directly above the rhizoids. Each sporangium brings as a swelling into which a number of nuclei flow and are eventually cut off from the sporangiophores by the formation of a septum.
Sporangium become black as it matures giving the mold its colour. Each spores when liberated can germinate into a new mycelium
Sexual reproduction of Rhizopus stolonifera
Occurs between different mating strains.
-when the two strains are in close proximity, hormones are produced that chase their hyphae tips to come together and develop into gametangia, which become separated from the rest of the fungal body by the formation of septa.
-walls between two touching gametangia dissolve and the two multinucleate protoplasts comes together. The fused nuclei form a young zygospores with several diploid nuclei.
Zygospores of Rhizopus stolonifera
Develop thick, rough black coat and become dormant, often for several months.
Meiosis occurs at the time of germination. The zygospore cracks open ad produced a sporangium that is similar to the asexually produced sporangium and the life cycle begins again
Rhizopus rot is caused by…..
Rhizopus stolonifera
Destructive to harvested fruit
-most commonly affects fruit in storage, during transit and at the marketplace.
-ripe fruit of peaches, nectarines, sweet cherries and plus are most susceptible.
-causes fuzzy appearance
