Ch+4+-+Organization+of+the+Cell

Ch+4+-+Organization+of+the+Cell - Organization of the Cell...

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Organization of the Cell Chapter 4 Cell Theory (1) Smallest unit to carry out all activities associated with life; maintenance, growth and division: (1) Contained in DNA codes (2) All cells come from other cells: (1) Single cell (prokaryotes, protists, fungi) (2) Multicellular (plants and animals) (3) Common ancestry Homeostasis Cells have many organelles , internal structures that carry out specific functions, that help maintain homeostasis: Appropriate internal environment which must be retained to allow biochemical function during constant changes in environment Cell organization and size are critical to maintaining homeostasis Plasma Membrane separates cell from external environment maintains internal conditions allows the cell to exchange materials with outer environment encloses internal structures (organelles) Genetic material; DNA,RNA Metabolic integrity (energy conversion) Manufacture (function and reproduction) Prokaryotic cells lack internal membrane organization (as we’ll see later) Include a cell wall that surrounds the plasma membrane providing an extra external layer (expand later) In stark contrast: Eukaryotic cells are divided into compartments by internal membranes Membranes provide separate, small areas for specialized activities Measurement
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Most cells are microscopic: Meter (m) (mm) millimeter = 1/1000m=10(-3)m (µm) micrometer = 1/1000,000m =10(-6)m (nm) nanometer = 1/1000,000,000m =10(-9)m (mm) millimeter = 1/1000m (µm) micrometer = 1/1000mm (nm) nanometer = 1/1000µm Cells are small: short distances between molecules travelling to their destinations - increases speed of reaction size must be limited or molecules required by the cell cannot be transported fast enough to sustain need Food in, waste products out pumps and gates for ion and molecule transportation Surface to Volume Ratio SVR ratio of plasma membrane (surface area) to cell’s volume regulates passage of materials into and out of the cell Increased according to cell shape; functional requirements e.g. small intestine microvilli (infolds) for nutrient absorption Fig 4:2 SVR Size and shape are also related to function: Sperm cells have flagella for locomotion Nerve cells extend to allow message transmittal Stacked epithelial cells become building blocks Fig 4:1 Biological Size Microscopes Anton Van Leeuwenhock; Royal Society of London First to report cells in animals
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Techniques not developed for 100 yr 19 th
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This note was uploaded on 07/17/2010 for the course 119:101 101 taught by Professor Martin during the Spring '10 term at Rutgers.

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Ch+4+-+Organization+of+the+Cell - Organization of the Cell...

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