Fungi - Overview, Characters, Classification, Examples, Importance , Multiple Choice questions: NEET
Overview. Alexander Fleming stated the importance of Penicillium notatum while he was working on bacteria Staphylococcus. According to Alexopoulos Fungi are nucleated with non chlorophyll bearing organisms, which reproduce by both asexually and sexually and their cell walls are made up of chitin. The study of fungi is called Mycology.
General account of Fungi- 👉Fungi can be seen in moist bread and rotten juices. Mushroom are edible fungi. Toad stool grow on dung is also fungi. 👉Unicellular fungi like yeast is used in production of wine and beer. Some multicellular fungi like penicillium is used in formation of Antibiotics.
👉White spot on mustard and Rust and Smut disease in plant are also caused by the fungi.
👉They are saprophytic in nature because they grow on dead matter of plants and animals and collect their food from these matter.
👉Fungi need warm and humid condition to grow. 👉Body of fungi is composed of long thread like structure called hyphae. The network of hyphae is called mycelium. The hyphae is coenocytic with multinucleated or septate.
👉They cannot make their own food due to lack of chlorophyll. They also act as Biofertilizer.
👉 Their cell wall is made up of Chitin and Polysaccharides.
🔴They reproduce vegetatively by budding, fragmentation, fission. 🔴Sexual reproduction in fungi may be isogamous, anisogamous and oogamous.
🔴Conidia or Sporangiospore or zoospore are mode of asexual reproduction.
🔵Extra Shot of Reproduction in Fungi
Fungi reproduce asexually by special structure like rhizomorph and sclerotia. Conidia, chlamydospore, endospores, basidiospore, uredospore, ascospores, pycniospores, teleutospore are spores in fungi that are formed in favourable condition.
🌑Dikaryophase
🔴In unfavourable condition, two same type of hyphae are come together and fuse through conjugation tube.
🔴Their protoplasm are fused through conjugation tube and make a single cell by the process of plasmogamy.
🔴At this stage, there are two nucleus in a cell therefore this stage is called Dikaryophase and nuclei are called dikaryon. 🔴Two nucleus in a cell is represented by n + n.
🔴Dikaryophase stage is frequently seen in member of Ascomycetes and Basidiomycetes.
🔴Now both nuclei are fused to each other through the karyogamy and form a diploid zygote.
🔴This zygote divides by meiosis and form many spores in fruiting bodies.
🌑Classification of fungi: Fungi are classified into four major groups on the basis of Morphology of mycelium, formation of spores and formation of fruiting bodies.
🌑Phycomycetes: 🔴Members of this group are found in moist, damp places, dead and decaying matter.
🔴Their mycelium is coenocytic with many nuclei. Their network of mycelium is well developed.
🔴They reproduce asexually by motile and nonmotile spores called zoospores and aplanospores respectively.
🔴They reproduce sexually by Zygospore that are formed by fusion of the protoplasts of two gametes.
🔴During fusion of gamete, a conjugation tube is formed to make the fusion of protoplast between the two cells of fungi.Therefore they are also called conjugation fungi.
🔴When both gametes are morphologically similar that are involved in sexual reproduction, then reproduction is isogamous.
🔴In anisogamous or oogamous , both gametes are not morphologically similar.
🔴They have some affinities with the algae therefore called as Algal fungi.
Example: 1. Rhizopus or Bread Mould 2 .Mucor. 3. Albugo (Parasite on Mustard.)
🌑Ascomycetes:
🔴They are also called Sac fungi and are regarded as higher fungi.
🔴It is the largest group of fungi including 1700 genus and 15000 species. 🔴They are saprotrophs , decomposers and parasites. They are also coprophilous because they may grow on cow dung.
🔴Their mycelium is branched and septate.
🔴They reproduce asexually by the conidia. These conidia are produced exogenously on special mycelium called conidiophore.
🔴They reproduce sexually by the specialised sexual spores called ascospores. Ascospores are formed endogenously usually eight in numbers and present within a sac-like structure called ascus. Therefore they are called ascomycetes.
🔴They are mostly multicellular like penicillium but some are unicellular like Saccharomyces.
For example- Aspergillus, Claviceps, Neurospora. Fusarium.
👌👌Remember- Neurospora is widely used in biochemical and genetic experiments.
🌑Basidiomycetes:
🔴The members are commonly called mushroom or bracket fungi or puffball.
🔴They are found in soil or damp trees or moist places.
🔴They may also be present in the plant body as parasites in the form of smut and rust.
🔴Their mycelium is branched and septate. 🔴Asexual mode of reproduction is unknown but they reproduce in vegetable mode by fragmentaion.
🔴They do not have any sex organs but they reproduce sexually by fusion of protoplast between two different cells by plasmogamy and form a club-shaped structure called the basidium. Hence they are also referred to as club fungi.
🔴Inside the basidium, by meiosis basidiospores are formed. These basidiospores are arranged in the fruiting bodies called basidiocarps.
Example: 1. Agaricus or Mushroom 2. Ustilago causes smut disease 3. Puccinia causes rust disease.
🌑Deuteromycetes:
🔴They are also called imperfect fungi because the sexual stage is not known in members of this group.
🔴They reproduces by asexual means mainly through conidia like Ascomycetes.
🔴They were grouped initially in ascomycetes but due to absence of sexual stage.
🔴They have been placed in different group.They are pathogenic and cause harmful diseases in humans and animals.
🔴Their mycelium is branched and septate.
🔴They are saprotrophs or parasite .They are also involved in mineral cycling in nature. Example: Alternaria, Colletotrichum, Trichoderma.
🔵Extrashot of Fungi Characters. They are almost cosmopolitan in nature and found in soil, water, air and even in plants and animal bodies. They have a filamentous and thallus-like body structure except yeast.They are devoid of chlorophyll therefore they are not green in color.Due to lack of chlorophyll, they do not perform photosynthesis.
They exhibit a heterotrophic mode of nutrition, thus they are not capable of making their own food. They are completely dependent on other organisms for their nutrition as Parasites and saprophytes. They are saprotrophic because they derive nutrition from the dead and decaying matter.
Their cell wall is mainly composed of chitin, a kind of polysaccharides. Along with the chitin, the cell wall of some fungi also have cellulose. Some fungi prefer be to live in darkness or in the absence of light hence they are photophobic and some may live in the presence of light called photophilic.
Body of fungi is composed of a network of thread-like structures called mycelium. The mass of mycelium forms specific fungal tissue called pseudo-parenchyma. Fungi store reserve food material in the form of glycogen.Some fungi make symbiotic association with algae and root of higher plants known as lichen and mycorrhiza respectively.
🌑Commercial use of Fungi
🔴At industrial scale, mushrooms are cultivated from fungi. Mushrooms have high nutritional value. Mushrooms are rich in vitamin B. It is regarded as a source of protein.
🔴Yeasts are used in the bread making industry. Yeast is also used in the production of wine whisky rum industries because yeast produces ethyl alcohol by fermentation.
🔴Penicillium is enriched in protein, vitamin A, vitamin B. It is added to increase the flavour to the cheese. Penicillin was the first antibiotics that was discovered from Penicillium notatum.
🔴Aspergillus produces citric acid, Gallic acid which is used in the chemical industry. .
1. How many Statement is / are correct with respect to Fungi.
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