Microbiology Fundamentals A Clinical Approach, 2nd ed. by Cowan Chapter 4.
Microbiology Fundamentals: A Clinical Approach, 2nd ed. by Cowan Chapter 4 Last Common Ancestor Correct Answer- Precursor cell to prokaryotes & eukaryotes Neither prokaryotic or eukaryotic The more complex cell type most likely emerged when a LCA cell engulfed smaller prokaryotic cells & coexisted with them History of Eukaryotes Correct Answer- First primitive eukaryotes were probably single-celled & independent Cells later began to aggregate & form colonies Cells became specialized within colonies Complex organisms later evolved and individual cells lost the ability to survive on their own Disease-causing eukaryotes Correct Answer- Protozoa, fungi, & helminths Theory of Endosymbiosis Correct Answer- One prokaryote engulfs another Symbiotic relationship allows for the development of organelles Engulfment of photosynthesis bacteria resulted in organelle chloroplasts Over time the cells became further specialized & created organs Cell Movement Correct Answer- Motility allows microorganisms to move toward nutrients & positive stimuli and away from harmful substances & stimuli Locomotion via cilia & flagella is common in protozoa, many algae, and a few fungal & animal cells Eukaryotic flagella v. Prokaryotic flagella Correct Answer- Eukaryotic flagellum 10x thicker Covered by extension of cell membrane Long, sheathed cylinder containing regularly spaced microtubules in a 9+2 arrangement Microbuses slide past each other creating a whipping emoting that requires expenditure of energy Cilia Correct Answer- Similar in structure to flagella, but are shorter & more numerous Back & forth beating in oar-like strokes instead of propeller motion like flagella Only found in single group of protozoa and in certain animal cells (trachea, fallopian tubes) Occur all over the cell surface Also function as feeding & filtering structures Glycocalyx Correct Answer- Outermost layer that comes into direct contact with the environment Usually composed of polysaccharides & appears as a network of fibers, a slime layer, or a capsule Functions: protection, adherence to surfaces, reception of signals from another cells & the environment Cytoplasmic membrane Correct Answer- Typical bilayer of phospholipids in which protein molecules are embedded Contain sterols of various kinds Serves as selectively permeable barrier Relative rigidity gives stability to membrane
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