Practical #1 Flashcards
five-kingdom classification and three domain
Monera (unicellular prokaryotes including bacteria and cyanobacteria)
Protista (unicellular eukaryotes including protozoa and unicellular algae)
Plantae (autotrophs)
Fungi (saprotrophs)
Animalia (heterotrophs)
Archaea Eukarya and bacteria
Fungi
Fungi are the heterotrophs that live on decomposing organic matter and are called saprophytes. Most are aerobic or facultative aerobes, grow terrestrial in slight moisture, with high humidity and acidic environment. Except Chytrids with flagellated gametes that have adapted to live in water, all fungi are non-motile and found in terrestrial habitat. Fungi are economically important as they are used in production of beer, wine, alcohol, bread (Saccharomyces cerevisiae), Sake (Aspergillus), cheese (for adding flavor), and antibiotics (Penicillium- antibacterial penicillin). There is also a symbiotic role for fungi as lichens (fungi and photosynthetic organisms) or mycorrhizae (symbiosis with plants).
Mold
Filamentous fungi (mold) have long branching cellular structure called hyphae that connects the two or more dividing cells and shares the cytoplasm. Several hyphae may form a mat called a mycelium.
Yeast
Yeasts are unicellular fungi with oval or spherical shape that replicate either by uneven (budding) or even (binary fission) cell division.
Reproduction of fungi
Most fungi replicate both sexually and asexually. Asexual reproduction can occur by fragmentation where a small portion of a colony is distributed (budding) or by asexual spore formation. Sexual reproduction occurs when two cells of opposite mating orientation fuse and form a diploid fruiting structure that differentiates to form sexual spores.
Fungal divisions
Divisions (for this course we focus on only 4 divisions)
1. Zygomycota form zygospores
2. Ascomycota form ascospores
3. Basidiomycota form basidiospores
4. Chytridiomycota form zoospores
And the none taxonomic group of: Deuteromycota do not form any sexual spores.
Zygomycota
Zygomycota produce the sexual spores, zygospores from the fusion of hyphae of different mating types. A mature zygospore of Rhizopus is shown with harden cell wall representing the sexual stage. The vegetative or asexual stage is recognized by the asexual spores (sporangiospores) formed in the sporangium (dark-colored structures located at the tip) of the stem-like structure known as sporangiophore.
Some Rhizopus spp. are opportunistic agents of human zygomycosis. They may cause serious (and often fatal) infections in humans and animals because of their rapid growth rate and growth at relatively high temperatures. Some species are plant pathogens (R. stolonifer, R.microspores); two are used in food fermentation (R. oligosporus, is used in the production of tempeh, a fermented food derived from soybeans; R. oryzae and S. cerevisiae are used in the production of sake, as one fungus reduces starch in rice to glucose, while the other ferments the glucose to alcohol). R. stolonifer, commonly called bread mold, appears as a white mycellial-growth with black sporangia and produces black spores.
Ascomycota
Saccharomyces cerevisiae, baker’s yeast, is a member of this group of fungi that is widely used in food industry. Record and draw observations. Lichens are also ascomycetes forming symbiotic relation with photosynthetic algae. These are sac fungi forming sexual ascospores (4 meiotic cells) in a pod-like structure called an ascus.
Basidiomycota
The Basidiomycetes include fungi that form fruiting bodies large enough to be visible to the naked eye. These fruiting structures are termed mushrooms (when edible) or toadstools (when poisonous).
Coprinus is a basidiomycete, notice the stalk (or stipe), which supports the cap at the top of the mushroom. Beneath the cap are numerous gills which give rise to sexual basidiospore. The fruiting structure is diploid, produced by the mating of haploid mycelia in the soil.
Chytridiomycota
Saprobic – degrade chitin or keratin Act as parasites
*aquatic fungi
Deuteromycotes
Coprinus: a) a large species of Coprinus, b) a cross-section of the fruiting body, c) the immature basidiospore group reproduce asexually, but they do not form sexual spores and hence often called fungi imperfecti. Aspergillus (Division Ascomycota) and Penicillium (Division Ascomycota) are common fungi representative of the group Deuteromycetes. Candida albicans (Division Ascomycota), the yeast is also a member of this group that causes vaginal infections. These organisms do not show cell-cell fusion and hence do not produce sexual zygospores. Instead they produce asexual spores by sporangia.
Penicillium
Ascomycota
Several Penicillium molds, including P. chrysogenum, P. roquefortti, and P. glaucum have blue or blue-green conidia. P. chrysogenum is the first species used to produce the antibiotic penicillin, while P. roquefortti is used to flavor Roquefort and Stilton cheeses, and P. glaucum is used to flavor Blue and Gorgonzola cheeses. Other Penicilliums have white conidia including P. camemberti and P. candida and are used in making of camembert and brie cheeses. P. marneffei, a mold with yellow conidia, is a human pathogen cause penicilliosis in HIV patients and prevalent in Southeast Asia.
Aspergillus
Is the common contaminants of starchy foods (such as bread and potatoes), as well as grows in or on many plants and trees. A. niger can be found growing on damp walls, as a major component of mildew. In Asian countries, alcoholic beverages such as Japanese sake are made from rice. First, A. oryzae (koji mold) converts the starch in the rice to sugars (saccharification), which then subsequently fermented by other microorganisms such as yeast (Saccharomyces) and/or lactic acid bacteria. A. niger ferments glucose to citric acid, and represents the main source of citric acid production as well as many commercial enzymes including those used in laundry detergents. A. terreus secretes a compound, and was the initial source of lovastatin (Lipitor), a cholesterol- reducing drug. A. fumigatus, A. flavus, and sometimes, A. niger are human pathogens that cause lung and systemic infections called aspergillosis. A. parasiticus is a food-contaminating organism that produces the toxin and carcinogen, aflatoxin.
Oomycetes
Close relative of fungi
Saprolegnia is a member of the Oomycetes group referred to as water molds. They were once
included under the fungi due to the similar morphology such
as white threads emerging through decaying matter. During its life cycle, it undergoes both
asexual and sexual reproduction, the former by means of
biflagellated zoospores. Members of Oomycestes are responsible for many plant diseases and rapidly get infected via motile zoospores (e.g. potato blight, mildew of grapes).
protozoa
protozoa are a diverse group of unicellular eukaryotes found free-living in all kinds of habitats. They are consumers of living and decaying matter; some are parasites, others live symbiotically. Most protozoa possess a single nucleus, but some species may have two or more. They usually reproduce by splitting in two (binary fission), but sexual reproductive processes are also known to occur.
