chap03outline - Chapter 3 - Cells 3.1 Introduction (p. 49;...

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Chapter 3 - Cells 3.1 Introduction (p. 49; Fig. 3.1) A. The human body consists of 75 trillion cells. B. Human cells vary considerably in shape and size. C. Differences in cell shape make different functions possible. 3.2 A Composite Cell (p. 49) A. A composite cell includes many known cell structures. B. A cell consists of three main parts---the nucleus, the cytoplasm, and the cell membrane. C. Within the cytoplasm are specialized organelles that perform specific functions for the cell. D. Cell Membrane (p. 49; Fig. 3.2) 1. The cell membrane regulates the movement of substances in and out of the cell, participates in signal transduction, and helps cells adhere to other cells. 2. General Characteristics (p. 51) a. The cell membrane is extremely thin and selectively permeable. b. It has a complex surface with adaptations to increase surface area. 3. Cell Membrane Structure (p. 51; Fig. 3.3) a. The basic framework of the cell membrane consists of a double layer of phospholipids, with fatty acid tails turned inward. b. Molecules that are soluble in lipids (gases, steroid hormones) can pass through the lipid bilayer. c. Embedded cholesterol molecules strengthen the membrane and help make the membrane less permeable to water-soluble substances. d. Many types of proteins are found in the cell membrane, including transmembrane proteins and peripheral membrane proteins. e. Membrane proteins perform a variety of functions. f. Some proteins function as receptors on the cell surface, starting signal transduction. g. Other proteins aid the passage of molecules and ions. h. Proteins protruding into the cell anchor supportive rods and tubules. i. Still other proteins have carbohydrates attached; these complexes are used in cell identification. Membrane proteins called cellular adhesion molecules (CAMs) help determine one cell’s interactions with others. E. Cytoplasm (p. 52; Table 3.1) 1. The cytoplasm consists of a clear liquid (cytosol), a supportive cytoskeleton, and networks of membranes and organelles. a. Endoplasmic reticulum (p. 52; Fig. 3.4) is made up of membranes, flattened sacs, and vesicles, and provides a tubular transport system inside the cell. i. With ribosomes, endoplasmic reticulum (ER) is rough ER, and functions in protein synthesis. ii. Without ribosomes, it is smooth ER, and functions in lipid synthesis. b.
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chap03outline - Chapter 3 - Cells 3.1 Introduction (p. 49;...

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