Essay about A Survey of Eukaryotic Cells and Microorganisms

982 Words Oct 8th, 2011 4 Pages
A Survey of Eukaryotic Cells and Microorganisms

HISTORY OF EUKARYOTES: 1. Evidence indicates that the first Eukaryotic cells first appeared on the earth approximately 2 billion years ago. Fossilized cells appear in shale sediments from China, Russia and Australia the date from 850-950 million years ago. 2. Biologists have discovered evidence to suggest that the eukaryotic cell evolved from prokaryotic organisms by a process of intracellular symbiosis. 3. Some of the organelles that distinguish eukaryotic cells originated from prokaryotic cells that became trapped inside them. 4. The structure of these first eukaryotic cells was so versatile that eukaryotic microorganisms soon spread out into available habitats and
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Microscopic fungi are known as yeast and molds. A. Overall Morphology: At the cellular microscopic level, fungi are typical eukaryotic cells eigh thick cell walls. Yeasts are single cells that form buds and pseudohyphae ( a chain of easily separated spherical to sausage-shaped yeast cells partitioned by construction rather than by septa) . Hyphae are long tubular filaments that can be septate or nonseptate and grow in a network called a mycelium (the filamentous mass that makes up a mold. Composed of hyphae). Hyphae are characteristic of the filamentous fungi called molds. B. Nutritional Mode/ Distribution: All are heterotrophic (An organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition). The majority are harmless saprobes (a microbe that decomposes organic remains from dead organisms), living of substrates (molecule upon which enzymes acts) such as dead animal or plant tissues. A few are parasites (An organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host). Distribution is extremely widespread in many habitats. C. Reproduction: Primarily through spores formed on special reproductive hyphae. In asexual reproduction, spores are formed through budding, partitioning of a hypha or in special sporongenus structures, examples are conidia (asexual fungal spores shed as free

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