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Unformatted text preview: 1 UNIT II. Cell Chapter 4 General Features of Cells CO 4 3 Student Learning Outcomes: Describe various microscopic techniques, emphasizing differences in resolution and contrast. Compare and contrast basic cell structure between prokaryotes and eukaryotes. Highlight important structural characteristics and cellular functions of cytoskeletal elements. Define the term semiautonomous, and outline the general functions of organelles that fall into this category. 4 Cell theory (p. 61) 1. All living things are composed of one or more cells 2. Cells are the smallest units of living organisms 3. New cells come only from pre-existing cells by cell division 5 Microscopy (pp. 61-64) Magnification Ratio between the size of an image produced by a microscope and its actual size Resolution Ability to observe two adjacent objects as distinct from one another Contrast Can be enhanced using dyes 6 Light microscope Uses light for illumination Resolution 0.2 m Electron microscope Uses an electron beam Resolution 2 nm Fig. 4.1, p. 62 8 Electron microscopes Transmission electron microscopy (TEM) Thin slices stained with heavy metals Some electrons are scattered while others pass through to form an image Scanning electron microscopy (SEM) Sample coated with heavy metal Beam scans surface to make 3D image Fig. 4.3, p. 63 10 Prokaryotic cells (pp. 64-65) Simple cell structure Lack a membrane-enclosed nucleus 2 categories- bacteria and archaea Both small Bacteria- abundant, most not harmful Archaea- less common, often found in extreme environments 11 Typical bacterial cell Plasma membrane Cytoplasm Nucleoid Ribosomes Fig. 4.4, p. 65 13 Typical bacterial cell Plasma membrane- barrier Cytoplasm- contained inside plasma membrane Nucleoid- region where genetic material found Ribosomes- involved in protein synthesis 14 Eukaryotic cells (pp. 65-67) DNA housed inside nucleus Eukaryotic cells exhibit compartmentalization Organelle- subcellular structure or ...
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