Kingdom Protista & Fungi PDF

Kingdom Protista All single celled organisms are placed under the Kingdom Protista. The term Protista was first used by Ernst Haeckel in the year 1886. This kingdom forms a link between other kingdoms of plants, animals and fungi. Protists represent an important step in early evolution. The first pr...

Kingdom Protista All single celled organisms are placed under the Kingdom Protista. The term Protista was first used by Ernst Haeckel in the year 1886. This kingdom forms a link between other kingdoms of plants, animals and fungi. Protists represent an important step in early evolution. The first protists evolved probably 1.7 billion years ago. Members of Protista are primarily aquatic in nature. It is a very large group comprising of at least 16 phyla. Many protists like algae are the primary producers in the aquatic ecosystem, some protists are responsible for serious human diseases like malaria and sleeping sickness. Kingdom Protista is a diverse group of eukaryotic organisms. Protists are unicellular, some are colonial or multicellular, they do not have specialized tissue organization. The simple cellular organization distinguishes the protists from other eukaryotes. The cell body of the protists contain have a nucleus which is well defined and membrane bound organelles. Some have flagella or cilia for locomotion. Reproduction in protists is both asexual and sexual. They live in any environment that contains water. Characteristics of Kingdom Protista General characteristics of Kingdom Protista are as follows:  They are simple eukaryotic organisms.  Most of the organisms are unicellular, some are colonial and some are multicellular like algae.  Most of the protists live in water, some in moist soil or even the body of human and plants.  These organisms are eukaryotic, since they have a membrane bound nucleus and endomembrane systems.  They have mitochondria for cellular respiration and some have chloroplasts for photosynthesis.  Movement is often by flagella or cilia.  Protists are multicellular organisms, they are not a plant, animal or fungus.  Respiration - cellular respiration is primarily aerobic process, but some living in mud below ponds or in digestive tracts of animals ares strict facultative anaerobes.  Nutrition - they can be both hetreotrophic or autotrophic.  Flagellates are filter feeding, some protists feed by the process of endocytosis (formation of food vacuole by engulfing a bacteria and extending their cell membrane).  Reproduction - some species have complex life cycle involving multiple organisms. Example: Plasmodium. Some reproduce sexually and others asexually.  They can reproduce by mitosis and some are capable of meiosis for sexual reproduction.  They form cysts in adverse conditions.  Some protists are pathogens of both animals and plants. Example: Plasmodium falciparum causes malaria in humans.  Protists are major component of plankton. Kingdom Protista Classification Kingdom Protista are categorized into two taxons: Protozoans - animal-like single-celled organisms. Algae - plant-like single or multi-celled organisms. Animal-like Protists – PROTOZOANS Protists that have resemblance to animals are known as protozoans. They in moist and watery enviroments. The characteristics similar to animals are - their ability to move and their inability to produce their own food (heterotrophs). They differ from animals being unicellular while animals are multicellular. Protozoans are classified on the way they move into four categories:  Sacordinians - move using pseudopod.  Zooflagellates - move using flagella.  Ciliaphorans - move using cilia.  Sporozoans - forms spores. Phylum Sarcodina - The movement in sarcodinians is by extending lobes of cytoplasm known as pseudopodia. The pseudopoda is used for movement and feeding. During the formation of the pseudopodia the cytoplasm streams into the lobe causing the lobe to 'ooze' and grow. Because of this the peudopodians have a 'blob like appearance. Example: Amoeba, Foraminiferans. Phylum Mastigophora (Zooflagellata) - These protozoans move with the help of flagella. Most of them are parasitic. Many flagellates are seen in the intestine of humans, in termites and other animals, some flagellates are harmful. Example: Trypanosoma gambiense causes sleeping sickness in cattle and human. For example euglena Euglena Euglena is a eukaryotic unicellular organism, it contains the major organelles found in more complex life. This protist is both an autotroph, meaning it can carry out photosynthesis and make its own food like plants, as well as a heteroptoph, meaning it can also capture and ingest its food. When acting as a autotroph, the Euglena utilizes its chloroplasts (which gives it the green colour) to produce sugars by photosynthesis, when acting as a heterotroph, the Euglena surrounds the particle of food and consumes it by phagocytosis, or in other words, engulfing the food through its cell membrane. Due to this adaptation, many Euglena are considered mixotrophs: autotrophs in the light and heterotophs in the dark. Locomotion comes in the form of either the rotating flagellums, or the flexible pellicle membrane. Morphology and Anatomy  Euglena has an elongated cell measuring 15-500 micrometres  Mostly green in colour due to the presence of chlorophyll pigment  Some of the species of euglena contain carotenoid pigments, which give it distinct colour like red  Euglena is unicellular having one nucleus  Euglena lacks the cellulose cell wall present in a plant cell  There is a presence of a flexible outer membrane known as a pellicle, which supports the plasma membrane. The pellicle is composed of a proteinaceous strip and supporting microtubules. The pellicle gives flexibility to the cell and an ability to contract and change its shape  A thin plasma membrane is present, which encloses the cytoplasm and cell organelles  It contains a contractile vacuole which removes excess water  There is inward pocket near the base of flagella called a reservoir, where contractile vacuole dispels excess water  Various cell organelles such as mitochondria, endoplasmic reticulum and Golgi bodies are present Nutrition  Euglena contains chloroplast having chlorophyll. These chloroplasts have the green algal origin and seemed to have acquired due to endosymbiotic relationship  They perform photosynthesis, but also require other organic nutrients and vitamins such as vitamin B12  Some of the photosynthetic euglenoids lose their chlorophyll when they grow in the dark and obtain nutrients heterotrophically from organic matter  Some species of Euglena are also heterotrophs   The heterotrophic species of Euglena either absorb organic compounds from the surrounding water or engulf bacteria and protists by phagocytosis within the food vacuoles  The chloroplast of Euglena contains pyrenoids, which is used to synthesize paramylon, a ꞵ-1, 3 polymer of glucose  Food is stored in the form of paramylon, which provides energy when there is no light  Some species of Euglena produce an alkaloid known as euglenophycin, which is found to kill fishes  Euglena is cultivated for large scale production in some countries like Japan for commercial production of paramylon. Some species of Euglena have shown to contain vitamin E (⍺-tocopherol) and high content of astaxanthin Locomotion and Phototaxis movement  It has an eyespot also known as stigma, that contains photoreceptors for detection of light and involved in phototaxis  Light detected by the eyespot is focused on paraflagellar body  One or two flagella are present, which help in locomotion  Mostly two flagella are present, that originates from a small reservoir inside the cell  One short flagellum is present, which does not protrude out of the cell, the long flagellum is used for swimming Reproduction  Euglena reproduces asexually by binary fission, they divide longitudinally  Their lifecycle consists of a free-swimming and a non-motile stage  It produces thick-walled protective cyst that can withstand unfavourable conditions, this is characteristic of a non-motile stage  Some euglenoids make reproductive cyst under unfavourable conditions. Many Euglenoids gather together, leave their flagella and get enclosed in a gelatinous substance. Individual Euglena produces reproductive cyst, which produces daughter cells by binary fission. Under favourable conditions, these daughter cells become flagellated and come out of the mass. This is known as the palmelloid stage of the lifecycle Phylum Ciliophora (Ciliates) - Protozoans of this phylum move with hair like structures called cilia. The cilia stick out of their cells. The movement of cilia is paddle like, it sways back and forth for movement and fast beating of the cilia causes movement of the organism. The cilia is also used to sweep food particles into the organism. Example: Paramecium - It is a ciliate protozoan found in fresh water and ponds. It commonly known as the slipper animal-cule. Phylum Sporozoa - All members of this phylum are non-motile and parasitic. They forms spores and hence the name sporozoa. They lack locomotory structures and they are carried in their hosts by their body fluids. Many sporozoans causes serious diseases in humans. Example: Plasmodium - this parasite causes malaria in humans. Life cycle of Plasmodium The malaria parasite life cycle involves two hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host. Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites. (Of note, in P. vivax and P. ovale a dormant stage [hypnozoites] can persist in the liver (if untreated) and cause relapses by invading the bloodstream weeks, or even years later.) After this initial replication in the liver (exo-erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ). Merozoites infect red blood cells. The ring stage trophozoites mature into schizonts, which rupture releasing merozoites. Some parasites differentiate into sexual erythrocytic stages (gametocytes). Blood stage parasites are responsible for the clinical manifestations of the disease. The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal. The parasites’ multiplication in the mosquito is known as the sporogonic cycle. While in the mosquito’s stomach, the microgametes penetrate the macrogametes generating zygotes. The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts. The oocysts grow, rupture, and release sporozoites , which make their way to the mosquito’s salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle. Plant-like Protists - ALGAE Plant-like protists have chlorophyll like that in plants. The green substance in their cells enable them to make food bu photosynthesis. They produce and release oxygen like the plants. It is believed to be the most supply of oxygen on Earth is from the plant-like protists. The plant-like protists are the major food source and primary producers for water organisms. Phylum Chlorophyta (Green Algae) - The green algae include unicellular and multicellular algae. They are mostly fresh water. Body is sheet-like thallus. They have cell walls made of cellulose and pectin. Food is reserve starch which is stored in pyrenoids. Example: Spirogyra - it is a unicellular green alga, it grows as a green thread or filament. Phylum Rhodophyta (Red Algae) - Red algae are mostly large and multicellular. They grow in oceans. The algae 'Nori' and Gelidium are used as food, in parts of Asia. Carragean and agar are glue- like substances in red-a;gae. Agar is used as a medium used for growing bacteria and other organisms under laboratory conditions. Agar is also used to make gelatin capsules. and a base for cosmetics. Carragean is used as a stabilizer and thickener in dairy products. It is also used to give toothpaste its creamy texture. Phylum Phaeophyta (Brown Algae) - Brown algae are multicellular. They grow on rocks in shallow water of the sea. Large brown algae are called kelps. Kelps may grow densely in the sea and form kelp forests. They form important food sources for fish and invertebrates. The brown algae growing on rocks are known as rockweed. Example of rockweed is Sargassum. Algin is a substance derived from some algae which is used in making ice cream, lotion and plastics. Phylum Chrysophyta (Golden algae) - 'Chryso' means 'color of gold'. There are three types of golden-algae: yellow-green algae, golden brown algae, diatoms. Diatoms are the most abundant and are found in seawater and freshwater habitats. The shell of diatoms are made of silica. They are major source of food to may aquatic organisms. The shells of fossil diatoms form thick deposits on the sea floor known as 'diatomaceous earth'. It is used as water filters, abrasive and to add sparkling to products such as paint and fingernail polish. Phylum Pyrrophyta (Fire Algae) - It contains of species of one-celled algae called dinoflagellate which means 'spinning swimmers'. They store food in the form of starch and oils. The red color is due to chlorophyll a and c and xanthophylls. These organisms have ability of bioluminescence. Almost all species like in marine water. Some species causes the 'red tide phenomenon'. The dinoflagellates causing red tides are known as Gonyaulax, which contain a neurotoxin and are poisonous to marine fauna. Economic Importance of Protists Protists are useful in the following manners: Source of food - Some protists like kelps are edible. Source of commercial products - Marine protists are source of useful substances like algin, agar, carragean and antiseptics. Primary producer of aquatic ecosystem - Many protists are primary producers, they play a basic role in food cahins, providing food and oxygen. Source of medicines - Sodium laminaria sulphate, Fucoidin, Heparin are algal products used as blood coagulants. Lyngbya produces an anti-cancer compound. Source of mineral - Kelps are rich in sodium, potassium, iodine etc, they are good source of minerals. Biological research - They are used in biological research, e.g., Chlorella is unicellular, non- motile alga. Pathogens - Thhese ar pathogenic organisms and may cause many disease in man and also in fruits and vegetables it causes late blight potatoes and causes. Fungi Fungi (singular fungus) are the eukaryotic organisms that belong to the Kingdom Fungi. They have no chlorophyll pigments and vascular tissues. The body consists of a single cell to branched filamentous hyphae that often produce specialized fruiting bodies. The special characteristic of fungi is that they grow rapidly and die soon. To name a few – the appearance of black spots on bread left outside for some days, the mushrooms and the yeast cells, which are commonly used for the production of beer and bread are also fungi. They are also found in most of the skin infections and other fungal diseases. Examples of Fungi, the Following are the common examples of fungi:  Yeast  Mushrooms  Moulds   Truffles If we observe carefully, all the examples that we cited involve moist conditions. Thus, we can say that fungi usually grow in places which are moist and warm enough to support them. Distinguishing Characteristics  The non-motile cells belong to the kingdom Fungi.  The cell walls of these non-motile cells are made of chitin.  Fungi are heterotrophic organisms. The only difference between other heterotrophic animals and fungi is that fungi digest and then ingest the food. Fungi release enzymes on the body of the other living things and thrive on them.  Fungi lack chlorophyll, which is a pigment used by plants to produce food. Most types of fungi are saprophytic in nature, which implies that they feed on dead and decaying matter.  There is no embryonic stage for fungi. A fungus develops from spores, and are both sexual and asexual.  Though most of the fungi are single cellular, most of the fungi species grow as multicellular filaments called hyphae. The hyphae form a mass called the mycelium.  An interesting characteristic of fungi is that like a plant, fungi too has an alternation of generations.  The cytoplasmic ultrastructure is similar to plant cells. However, they differ significantly in their structures and organelles.  Fungi store their food in the form of glycogen.  The cell membrane of a fungus has a unique sterol and ergosterol.  Some types of fungi are parasitic and can lead to infections, thus, affecting the host.  Many of the fungi have a small nuclei with repetitive DNA.  Mitosis takes place without dissolution of the nuclear envelop.  They propagate through the process of spore release.  Pheromone is a chemical substance produced by fungi, which leads to the sexual reproduction between male and female fungi cells.  Some fungi are macroscopic and can be seen by naked eyes. Mold or mushrooms are examples of macroscopic form of fungi. The associations between roots and fungi are called mycorrhizae. The roots provide essential nutrients for the growth of the fungi. In return, the large mass of fungal hyphae acts as a virtual root system for the plants, increasing the amount of water and nutrients that the plant may obtain from the surrounding soil. A plant that forms an association benefiting both the fungus and the plant is a "host." Large numbers of native desert plants are hosts to these fungi and would not survive without them. There are two types of mycorrhizae, these are  In ectomycorrhizae (external), the fungus produces a sheath around the root. This sheath then produces hyphae that grow into the root and out into the soil.  Endomycorrhizae (internal) do not produce a sheath; the hyphae grow within the cells and out into the soil. These are far more common than the ectomycorrhizae Classification of Fungi Kingdom Fungi are classified based on different modes. The different classification of fungi is as follows: Based on Mode of nutrition On the basis of nutrition, kingdom fungi can be classified into 3 groups. 1. Saprophytic – The fungi obtain their nutrition by feeding on dead organic substances. Examples: Rhizopus, Penicillium and Aspergillus. 2. Parasitic – The fungi obtain their nutrition by living on other living organisms (plants or animals) and absorb nutrients from their host. Examples: Taphrina and Puccinia. 3. Symbiotic – These fungi live by having an interdependent relationship association with other species in which both are mutually benefited. Examples: Lichens and mycorrhiza. Lichens are the symbiotic association between algae and fungi. Here both algae and fungi are mutually benefited as fungi provide shelter for algae and in reverse algae synthesis carbohydrates for fungi. Based on Spore Formation Kingdom Fungi are classified into the following based on the formation of spores: 1. Zygomycetes – These are formed by the fusion of two different cells. The sexual spores are known as zygospores while the asexual spores are known as sporangiospores. The hyphae are without the septa. 2. Ascomycetes – They are also called as sac fungi. They can be coprophilous, decomposers, parasitic or saprophytic. The sexual spores are called ascospores. Asexual reproduction occurs by conidiospores. Example – Saccharomyces 3. Basidiomycetes – Mushrooms are the most commonly found basidiomycetes and mostly live as parasites. Sexual reproduction occurs by basidiospores. Asexual reproduction occurs by conidia, budding or fragmentation. Example- mushrooms 4. Deuteromycetes – They are otherwise called imperfect fungi as they do not follow the regular reproduction cycle as the other fungi. They do not reproduce sexually. Asexual reproduction occurs by conidia. Example – Trichoderma. 5. The oomycetes- also known as “water molds”, are a group of several hundred organisms that include some of the most devastating plant pathogens. The diseases they cause include seedling blights, damping-off, root rots, foliar blights and downy mildews. Some notable diseases are the late blight of potato, downy mildew of grape vine, sudden oak death, and root and stem rot of soybean. Because of their filamentous growth habit, nutrition by absorption, and reproduction via spores, oomycetes were long regarded by plant pathologists as lower fungi. However, as our understanding of evolutionary relationships has grown, it is now clear that this group of organisms is unrelated to the true fungi. Indeed, fungi appear more closely related to animals than to oomycetes, and oomycetes are more closely related to algae and to green plants. One of the most distinguishing characteristics is the production of zoospores produced in sporangia. The anterior flagellum of a zoospore is a tinsel type, while the posterior flagellum is a whiplash type; both are typically attached in a ventral groove. Although wall-less, zoospores retain a consistent but flexible shape. Zoospores can swim in water films on leaf surfaces, in soil water, in hydroponic media and in natural bodies of water. Oomycetes can often be “baited” from soil water, streams or ponds, and it is thought that zoospores are attracted to the baits. After a time of free swimming the zoospores settle on a surface, retract  their flagella, and secrete a mucilaginous matrix which affixes them to the surface. Sporangia of different taxa within the group are of diverse shapes and characteristics. They may be terminal or intercalary (within a hyphal filament), bulbous or not, and if terminal, caducous (sporangia detach readily) or not. Based on reproduction Reproduction in fungi is both by sexual and asexual means. The sexual mode of reproduction is referred to as teleomorph and the asexual mode of reproduction is referred to as anamorph. Vegetative reproduction – By budding, fission and fragmentation Asexual reproduction – This takes place with the help of spores called conidia or zoospores or sporangiospores Asexual Reproduction Fungi reproduce asexually by fragmentation, budding, or producing spores. Fragments of hyphae can grow new colonies. Mycelial fragmentation occurs when a fungal mycelium separates into pieces with each component growing into a separate mycelium. Somatic cells in yeast form buds. During budding (a type of cytokinesis), a bulge forms on the side of the cell, the nucleus divides mitotically, and the bud ultimately detaches itself from the mother cell. The most common mode of asexual reproduction is through the formation of asexual spores, which are produced by one parent only (through mitosis) and are genetically identical to that parent. Spores allow fungi to expand their distribution and colonize new environments. They may be released from the parent thallus, either outside or within a special reproductive sac called a sporangium. There are many types of asexual spores. Conidiospores are unicellular or multicellular spores that are released directly from the tip or side of the hypha. Other asexual spores originate in the fragmentation of a hypha to form single cells that are released as spores; some of these have a thick wall surrounding the fragment. Yet others bud off the vegetative parent cell. Sporangiospores are produced in a sporangium. Sexual reproduction – ascospores, basidiospores, and oospores Sexual reproduction introduces genetic variation into a population of fungi. In fungi, sexual reproduction often occurs in response to adverse environmental conditions. Two mating types are produced. When both mating types are present in the same mycelium, it is called homothallic, or self-fertile. Heterothallic mycelia require two different, but compatible, mycelia to reproduce sexually. Although there are many variations in fungal sexual reproduction, all include the following three stages. First, during plasmogamy (literally, “marriage or union of cytoplasm”), two haploid cells fuse, leading to a dikaryotic stage where two haploid nuclei coexist in a single cell. During karyogamy (“nuclear marriage”), the haploid nuclei fuse to form a diploid zygote nucleus. Finally, meiosis takes place in the gametangia (singular, gametangium) organs, in which gametes of different mating types are generated. At this stage, spores are disseminated into the environment. Economic importance of Fungi Fungi are one of the most important groups of organisms on the planet as it plays a vital role in the biosphere and has great economic importance on account of their both benefits and harmful effects. Following are some of the important uses of fungi: 1. Recycling – They play a major role in recycling the dead and decayed matter. 2. Food – Mushrooms species are edible which are cultured and are used as food by humans. 3. Medicines – There are many fungi which are used to produce antibiotics, to control diseases in humans and animals. Penicillin antibiotic is derived from a common fungi Penicillium. 4. Biocontrol Agents – Fungi are involved in exploiting insects, other small worms and help in controlling pests. Spores of fungi are used as spray-on crops. 5. Food spoilage – Fungi play a major role in recycling organic material and are also responsible for major spoilage and economic losses of stored food Mr. Chikonde, SMNS-CBU