BIOL125_Ch5 Text Notes

BIOL125_Ch5 Text Notes - BIOL 125 (Microbiology) Text Notes...

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BIOL 125 (Microbiology) Text Notes Chapter 5: Survey of Eukaryotic Cells and Microorganisms 1. HISTORY OF THE EUKARYOTES a. Endosymbiosis – the theory that eukaryotic cells arose when a much larger prokaryotic cell engulfed smaller bacterial cells that began to live and reproduce inside the prokaryotic cell. i. Dr. Lynn Margulis was the biologist most responsible for this theory. 2. FORM AND FUNCTION OF THE EUKARYOTIC CELL: EXTERNAL STRUCTURES See Figure 5.2 – Overview of Composite Eukaryotic Cell (end of Text Notes) a. In general, eukaryotic microbial cells have a cytoplasmic membrane, nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, vacuoles, cytoskeleton, and glycocalyx. Cell walls, chloroplasts, and locomotor organs are present in some eukaryotes. QuickTime ] and a decompres or are ne ded to se this picture. b. Locomotor Appendages: Cilia and Flagella i. Motility allows a microorganism to locate nutrients and migrate toward positive stimuli, and avoid negative stimuli. ii. Eukaryotic flagella are different from prokaryotic flagella. 1) Eukaryotic flagella are approximately 10 times thicker, more complex, and covered by an extension of the cell membrane. 2) A single flagellum a sheathed cylinder containing hollow microtubules that extend along the entire length. File: 24355285235c4811622db4f49e2a09ad08c63afa.doc Updated 8/14/09
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Text Notes Chapter 5 Page 2 a) There are nine pairs of microtubules surrounding a central pair, giving it a 9+2 arrangement, which is the universal pattern of flagella and cilia. 3) Cilia are similar to flagella, but are shorter and more numerous. a) Cilia are found only in certain protozoa and animal cells. c. The Glycocalyx i. Most eukaryotic cells have a glycocalyx, an outermost boundary that comes into direct contact with the environment. 1) The layer beneath the glycocalyx varies among eukaryotic groups. a) Fungi and most algae have a thick, rigid cell wall surrounding a cell membrane. b) Protozoa, a few algae, and all animal cells lack a cell wall and are encased primarily by a cell membrane. ii. The glycocalyx is usually composed of polysaccharides, and appears as a network of fibers, a slime layer, or a capsule. iii. The glycocalyx promotes adherence to surfaces and the development of biofilms. It also serves important receptor and communication functions, and offers some protection. d. Form and Function of the Eukaryotic Cell: Boundary Structures i. The Cell Wall. 1) The cell walls of fungi and algae are rigid, providing structural support and shape, but are chemically different that prokaryotic cell walls. a) Fungi cell walls have a thick, inner layer of polysaccharide fibers composed of chitin or cellulose and a thin outer layer of mixed glycans. b)
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BIOL125_Ch5 Text Notes - BIOL 125 (Microbiology) Text Notes...

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