Ectoplasm lends form to the cell body. Therefore, the germ cells may be called immortal in contrast to the somatic cells. Evidences in favour of Amoeba undergoing nuclear division in encysted condition are very rare. The Greek meaning describes this microbe as the Sea God Proteus that has an ever changing shape. The living protoplasm is broken down constantly by oxidation to produce heat, kinetic energy and waste products. Amoeba proteus exhibits both types of taxes, positive as well as negative, specifically to different stimuli. The outer part of the endoplasm near the posterior end contains a clear, rounded and pulsating vacuole filled with a watery fluid. The structure of nucleus of Amoeba proteus is like that of a honeycomb-lattice. About 200 such spores may be formed within a single parent. Answer Now and help others. It has also been observed that two amoebae come closer and unite together temporarily and get separated after some time. The nucleus has a firm nuclear membrane or nuclear envelope and contains a clear achromatic substance with minute chromatin granules or chromidia distributed uniformly near the surface. At about 24°C, the process takes about 20 to 30 minutes. Amoeba moves away from strong light and may change its direction a number of times to avoid it, but it may react positively to a weak light. Numerous large pseudopodia are formed at opposite poles, drawing both the daughter amoebae in opposite directions. Digestion of food takes place inside the food vacuole. The nuclear membrane is double-layered having pores. It is granular heterogeneous fluid containing bi-pyramidal crystals. The pseudopodia of Amoeba are known as lobo-podia due to their blunt, finger-like appearance and rounded tips. The food particles are either absorbed or thrown out and the contractile vacuole disappears. During the life of an Amoeba, before the period of reproduction, the nucleus plays an important role in the metabolic activities of the cell. When the digested food is reduced to molecular form, then the food vacuole buds off smaller and smaller secondary food vacuoles which carry away the digested food. Amoeboid cells are generally found within animal species, some forms of algae and even in fungi. Its ability to change shape is from the pseudopodia, which are common in eukaryotic microbes. The sides of lotus ponds and the water troughs are excellent places for the collection of amoebae. By repeating this process, the Amoeba can ingest and roll up long filaments of algae. Share Your Word File Blog. A very interesting feature of binary fission, observed in the division of nucleus, is the existence of multipolar nuclear spindle in the metaphase, which is reduced to tri-polar nuclear spindle in the mid-anaphase stage and finally reduced to unipolar nuclear spindle at the end of late anaphase. Contact with the food also results positive reactions. It results in the division of parent amoeba into two daughter amoebae. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Amoeba proteus characteristics; classification and diagram (well labelled), THEY ARE HETEROTROPHS THAT INGESTS FOOD BY A PROCESS CALLED ENDOCYTOSIS, SOME SPECIES OF AMOEBA E.G N. fowleri amoeba COULD BE HARMFUL TO HUMANS. In Amoeba proteus, there is a single conspicuous nucleus. The germ cells are related with reproduction, i.e., the production of new individuals. The food is captured by pseudopodia, usually by the formation of food cup, in which a pseudopodium embraces the prey from each side while a thin sheet advances over it from above pinning it to the substratum. It also retains the protoplasm within the cell. The vacuole fills rhythmically with fluid and then discharges it to the exterior. The honeycomb-like lattice just below the nuclear membrane first fragments and then disappears. Thus, it is probable that the chief function of the contractile vacuole is to regulate the water contents of Amoeba. Remote health initiatives to help minimize work-from-home stress; Oct. 23, 2020. The streaming of cytoplasm ceases within a few minutes in the piece without a nucleus but is resumed after a few hours. The Golgi apparatus appear as groups of sac-like tubules. When a tadpole turns into a frog, its tail shrinks and is reabsorbed. Amoeba consumes food either through the process of phagocytosis or pinocytosis. It is composed of a double layer of lipid and protein molecules. The endoplasm contains reserve food material in the form of plate-like or bi-pyramidal crystals. The metaphase stage is marked by the arrangement of the chromosomes at the equator. Amoeba Proteus exhibits positive geotaxis since it moves toward the centre of gravity like other animals. Smaller flagellates and ciliates appear to constitute the favorite food of Amoeba. According to Johnson (1930) and Hasley (1936), multiple fission does not occur in larger free living species such as Amoeba proteus and A. dubia but it may occur in smaller forms or parasitic amoebae. Eucaryotic. Weismann emphasised that the body of multicellular animals is formed of two types of cells: The somatic cells are related with the general maintenance of the body. In A. proteus, spores are formed internally. It expands (diastole) and contracts (systole) rhythmically and serves for excretion and osmoregulation. Amoeba Proteus exhibits the following biological significance: 1. The mitochondria provide the energy for actual formation and working of the vacuole. Amoeba proteus captures food and draws it into the body protoplasm through the agency of the pseudopodia, or rather, the protoplasm of the organism streams into pseudopodia around the prey, thus engulfing it (Fig. In the anaphase stage, the daughter chromosomes move towards opposite poles and the constriction of the nuclear membrane begins in the middle. Amoeba proteus is a one-celled microscopic animal about 0.25 mm (250 microns) in diameter and so transparent that it is invisible to the naked eyes. Characteristics of trajectory in the migration of Amoeba proteus. On the other hand, if freshwater amoebae are transferred to salt water their contractile vacuoles decrease and finally disappear altogether. Each amoebula is surrounded by a spore case to form a spore. The waste products of katabolism are urea, CO2, H2O and minerals. 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