Microbial World - Wiki. Educator. By Dr. Abdul Karim. Chapter Outline Introduction. Learning Objectives. Structure of the bacterial cell. Bacterial reproduction. Economic importance of bacteria. Activity: Observasion of bacteria under microscope. General morphology. Multiplication of bacteriophages. Economic importance. Activity: Observasion of viral plant diseases. Economic importance. Activity: Observation of yeast under microscope.
Answers to SAQs. References and further readings. You have learnt regarding organisms that can be seen with naked eye from the previous units of your learning material. Now we will discuss about organisms which can. It is so surprising, right? Among them some are too small that we can. These are the members of the kingdoms Eubacteria and Archaebacteria, are the most successful of all creatures on Earth, if success is measured by numbers of individuals. The meaning if the word bacteria is stalk. In essence they consist of cell protoplasm contained within a retaining structure or cell envelope. They are among the most common and ubiquitous organisms found on earth. For example, even a gram of soil can contain up to 1. They can also be found in diverse and extreme environments. Here we will discuss structure of a typical bacterial cell. Bacteria can move into the liquid medium with the help of flagella. Economic Importance of Fungi in Agriculture (full text) Uploaded by. ECONOMIC IMPORTANCE OF FUNGI IN AGRICULTURE It should be noted that, when we talk about economic importance. It contains 1. 0- 4. Sometimes, a pocket like small appendage developed inside the cell wall known as mesosome. Ribosomes and vacuoles are irregularly distributed within the bacterial cytoplasm. But nucleoid is present almost centre portion of the cell. Nucleoid is made by a double stand DNA. Bacteria are prokaryotic due to absence of nuclear membrane and nucleolus. It is very simple and very fast reproductive method. Cell is divided into two cells after attachment of cytoplasmic membrane. Both of two daughter cells receive nuclear materials. Both beneficial and harmful effects are occurred in bacteria. Economic Importance Of Viruses Pdf EditorPlant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology. Plant viruses are generally transmitted from plant to plant by a vector. They are of tremendous importance to man. Write an essay on the economic importance of bacteria. Their economic importance can be studied under two aspects: (A). Symbiotic bacteria also can fix nitrogen directly from the air. Man: Bacteria can produce different diseases in human bodies. Such as- . Disease. Bacteria Cholera. Vibrio cholerae Typhoid. Salmonella typhi Tuberculosis. Mycobacterium tuberculosis Dysentery. Bacillus dysenteri Tetanus. Clostridium tetanib. Animals: Bacteria can cause the different diseases in household animals. Plants: Bacteria can produce different disease in cultivated crops. Water Pollution: bacteria can causes the pollution of water and different diseases are spread through polluted water. Water born diseases like Cholera, Typhoid, Dysentery, Diarrhea etc occurs due to drink of polluted water. What is the meaning of the word bacteria? How bacteria can multiply? Which bacteria can produce subtilin? They are 1. 0 to 1. Viruses are incapable of independent growth in artificial media. They can grow only in animal or plant cells or in microorganisms. They reproduce in these cells by replication ( a process in which many copies or replicas are made of each viral components and then assembled to produce progeny virus). Thus viruses are referred to as obligate intracellular parasites. A virion is a complete, fully developed viral particle composed of nucleic acid and surrounded by a protein coat. This coat protects it from the environment and serves as a vehicle of transmission from one host cell to another. Viruses are classified by differences in the structures of these coats. The structure of the capsid is ultimately determined by the viral nucleic acid and accounts for most of the mass of a virus, especially of small one. The percentage of nucleic acid in relation to protein is about 1% for the influenza virus and about 5. In contrast to prokaryotic and eukaryotic cells, in which DNA is always the primary genetic material (and RNA plays an auxiliary role), a virus can have either DNA or RNA but never both. Generally plant virus contains RNA and animal virus contains DNA. Twort in England discovered bacteriophages, viruses that infect bacteria, independently in 1. Felix d. T2 bacteriophage is divided into two parts, are Head and Tail. A double stand DNA is situated spirally inside the cell and a protein coat surrounded the nucleic acid. Upper part of tail, such the connecting point of head and tail is called colar. The protein coat of tail is swollen and covered by protein. Six tail fibers and a baseplate present at the end of tail. The structure of these capsids has been revealed by electron microscopy. The viral nucleic acid is found within a hollow, cylindrical capsid that has a helical structure. The capsid of most polyhedral viruses is in the shape of an icosahedron, a regular polyhedron with 2. The best understood viral life cycles are those of the bacteriophages. Phages can multiply by two alternative mechanisms: the lytic cycle or the lysogenic cycle. The lytic cycle ends with the lysis and death of the host cell, whereas the host cell remains alive in the lysogenic cycle. But viruses also play a positive role for human beings. What kind of plant is virus? What kind of components are in virus? Which nucleic acid is in plant viruses? Which nucleic acid is in animal viruses? Thus, they either depend on a living host organism (in which case they are said to be parasites) or on decaying matter for their nutrition (thus called saprophytes). Like bacteria, their cell walls are made up of cellulose and chitin. There are many kinds of fungi. We may have seen them as green, white, gray, black, and orange molds on various things left in warm and moist conditions. The toadstools in the woods are another kind. Mushroom, bread mold, and yeasts also belong to the group of organisms called fungi. Most fungi multiply asexually by forming many spores. These spores are easily carried to places by wind, water, animals, or humans. Some sensitive people develop allergy when they inhale these spores. Fungi also multiply by budding. Other groups of fungi, however, reproduce sexually by fusing male and female hyphae in a process known as conjugation. Hyphae are branching filaments consisting of several cells. They represent the vegetative or asexual stage in the life of most fungi. Along the hyphae, root like structures that attach the fungi to a surface extend downward. Hyphae absorb nutrients from that surface. Spores are located in the sporangium. Black spots seen on stable bread are actually spores. These fruiting structures are used to classify fungi. Species of these types of fungi are called gill. Agaricus can grow on muddy soil, upper side of wood, compost manure, rotten straw, Cow dung etc. Agaricus can grow well in rainy season. Sometimes it can grow as a circle within the grass field. This type of cycle is called pericycle. Mycellium have many branch and sub- branches, and grow within the moist soil. Haphae of mycellium are septate. Hyphae are white colour and take nutrients from habit. Mycellium of hypha sometimes aggregates together and formed a rope like structure called rhisomorph. Fruiting bodies called basidia that produce spores are found on the side of gills. Mature spores fall to the ground. They may be carried by wind or water to other area. Mature fruiting body looks like umbrella and that. Some mushroom species are edible and others are poisonous. Ipil- ipil leaves, rice stalks, and banana leaves are used as growing surfaces. To these substrates, honey, coconut water, and urea may be added. Life saving antibiotic can produce from different fungi. Penicillin produces from Penicillium notatum. Sir Alexander Fleeming was discovered Penicillin in 1. They can also cause spoilage of food. Fungi decompose organic materials. Some fungi are parasitic on humans, animals, and plants. In humans, they can cause ringworm, athlete. Certain fungi may be caused for Wilting of crops like tomato, corn, banana, and papaya. Fungi may also attack seeds. Consequently, these seeds don. Stir the mixture thoroughly. What kind of plant is fungi? When penicillin was dicovered? Which fungus can produce penicillin? Bacillus subtilis. SAQ- 2. A. Protein and nucleic acid. Karim, M. A., S. A. Sultana, M. A. Islam, M. S. CAMPE and Bangladesh Open University. Bangladesh Open University. Muttaki, Faridunnesa, A. K. M. N. Bangladesh Open University. Microbiology (5th Ed.). Tata Mc. Graw- Hill Publishing Company Ltd. Life: The Science of Biology (4th Ed.). Environmental Microbiology.
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