BI13_Ch3 Text Notes

BI13_Ch3 Text Notes - ANATOMY AND PHYSIOLOGY 1 TEXT NOTES...

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ANATOMY AND PHYSIOLOGY 1 TEXT NOTES Chapter 3 – Cells: The Living Units 1. OVERVIEW OF THE CELLULAR BASIS OF LIFE a. Cells are the structural units of all living things. i. Cells are the smallest living unit and loss of cellular homeostasis underlies virtually every disease. ii. A cell’s shape reflects its function. iii. Regardless of type, all cells are composed chiefly of carbon, hydrogen, nitrogen, oxygen, and trace elements. iv. Human cells have three main parts: plasma membrane, cytoplasm, and nucleus. b. History. i. Robert Hook first observed plant cells in the late 1600’s. ii. Matthias Schleiden and Theodor Schwann stated that all living things are composed of cells. iii. Rudolf Virchow contended that cells arise only from other cells/ 1) Virchow’s proclamation challenged the Theory of Spontaneous Generation , which held that organisms arise spontaneously from garbage or nonliving matter. c. Cell Theory includes the following: i. A cell is the basic structural and functional unit of living organisms. ii. The activity of an organism depends on both the individual and the collective activities of its cells. iii. According the Principle of Complementarity , the biochemical activities of cells are dictated by the relative number of their specific subcellular structures. iv. Continuity of life has a cellular basis. 2. THE PLASMA MEMBRANE a. Plasma (Cell) Membrane – a fragile barrier and outer boundary of the cell. It separates the intracellular fluid inside the cell and the extracellular fluid outside the cell. b. The Fluid Mosaic Model i. Fluid Mosaic Model – depicts the plasma membrane as an exceedingly thin structure composed of a double layer, or bilayer, of lipid molecules with protein molecules dispersed in it. The proteins, many of which float in the fluid lipid bilayer, form a constantly changing mosaic pattern. 1) Lipid Bilayer – forms the basic “fabric” of the membrane and is constructed largely of phospholipids, with smaller amounts of cholesterol and glycolipids. a) Each phopholipid molecule has a polar “head” that is charged and is hydrophilic , and an uncharged nonpolar “tail” that is made of two fatty acid chains and is hydrophobic . File: b34b437ca2e517a098494a71ebf5efb8b9c837d6.doc Updated: 8/14/09
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TEXT NOTES Chapter 3 Page 2 b) All biological membranes have a sandwich-like structure: They are composed of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads exposed to water inside and outside the cell. c. Glycolipids – phospholipids with attached sugar groups found only on the outer plasma membrane surface and account for approximately 5% of the total membrane lipid. d. Approximately 20% of the outer membrane contains lipid rafts , dynamic assemblies of saturated phospholipids associated with unique lipids called sphingolipids and lots of cholesterol. e.
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This note was uploaded on 08/12/2009 for the course BI 13 taught by Professor Alexasawa,ph.d during the Spring '09 term at College of the Desert.

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BI13_Ch3 Text Notes - ANATOMY AND PHYSIOLOGY 1 TEXT NOTES...

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