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Chapter 5 Cell Structure and Function

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Chapter 5 Cell Structure and Function Powered By Docstoc
					   Chapter 5

Cell Structure and
     Function
         Basic Features of Cells

• All living things are composed of one or
  more cells
• All are enclosed by a plasma membrane
• All cells contain cytoplasm
• All cells obtain energy and nutrients from the
  environment
• All cells use DNA as a hereditary blueprint
   I. The history of cell study
• A. Robert Hooke—1665—coined the word
  cell, looked at cork cells
• B. Robert Brown—1831—discovered the
  "nucleus"
    I. The history of cell study
• C. Theodor Schwann—1838—viewed
  animal cells in cartilage
  – 1. Cells are the elementary particles (units) of
    plants and animals
• D. Mattias Schleiden—Cells are the
  fundamental basis of life
• E. Virchow—1858—All cells come from
  cells
    I. The history of cell study
• F. Cell theory
  – 1. All living things are composed of one or
    more cells
  – 2. Cells are the basic unit of structure and
    function
  – 3. All cells come from preexisting cells
         II. Attributes of cells
• A. Cell size
  – 1. 1–100µm
  – 2. Why is there a limit to cell size?
     • a. Surface-to-volume ratio
     • b. Distance from surface to center
        II. Attributes of cells
• B. Cell types
  – 1. Prokaryotic—no nucleus, circular DNA,
    ribosomes
  – 2. Eukaryotic—larger, nucleus, linear
    chromosomes, membranous organelles
           III. Cell structure
• A. All cells possess a plasma membrane,
  cytoplasm, genetic material
  – 1. Plasma membrane has phospholipid
    bilayer, embedded glycoproteins
    • a. Isolates cytoplasm from environment
    • b. Regulates molecular movement into and out of
      cell
    • c. Interacts with other cells/environment
           III. Cell structure
• A. All cells possess a plasma membrane,
  cytoplasm, genetic material (cont.)
  – 2. Genetic material—DNA, found in the
    nucleus (of eukaryotes)
  – 3. Cytoplasm—water, salts, organic
    monomers and polymers
    • a. Contains organelles
           III. Cell structure
• B. Organelles
  – 1. Endoplasmic reticulum consists of folded
    membranes attached to the nucleus
    • a. Rough ER is site of protein synthesis and
      protein secretion
  – 2. Ribosomes assemble amino acid
    monomers into polypeptide chains
    • a. Associated with the ER
    • b. Composed of RNA and proteins
            III. Cell structure
• B. Organelles (cont.)
  – 3. Golgi apparatus (dictyosomes) are
    membranous sacs associated with ER
     • a. Processing and transport of proteins, lipids
     • b. Synthesis and transport of polysaccharides
  – 4. Lysosomes are Golgi-derived vesicles
    containing digestive enzymes
            III. Cell structure
• B. Organelles (cont.)
  – 5. Mitochondria provide energy for cellular
    functions (respiration)
     • a. Membrane bound, numerous
     • b. Matrix/ cristae
     • c. Have their own DNA and ribosomes; self-
       replicate
                 III. Cell structure
• B. Organelles (cont.)
  – 6. Plastids
     • a. Chloroplasts—function in photosynthesis
        –   1)   Green—contain chlorophyll pigment
        –   2)   Stroma/grana (thylakoid stacks)
        –   3)   Have their own DNA and ribosomes; self-replicate
        –   4)   Up to 100 per cell
     • b. Mitochondria, plastids, and the endosymbiont
       hypothesis
           III. Cell structure
• B. Organelles (cont.)
  – 7. Vacuoles
     • a. Large, water-filled spaces (cell sap)
     • b. Can take up over 90% of cell volume
     • c. Surrounded by tonoplast (a single membrane)
            III. Cell structure
• B. Organelles (cont.)
  – 7. Vacuoles (cont.)
     • d. Functions:
        – 1) Storage of red/blue anthocyanins, acids, salts,
          wastes
        – 2) Maintain cell pressure (turgor pressure)—wilting
            III. Cell structure
• B. Organelles (cont.)
  – 8. Nucleus is control center of the cell
     • a. Membrane bound (nuclear envelope)
     • b. Contains nucleoli; synthesizes ribosomal RNA
     • c. DNA in chromosomes (DNA and proteins)
           III. Cell structure
• C. Cell walls in plant cells, prokaryotic
  cells, fungi
  – 1. Polysaccharide composition
  – 2. Function: support, protection
            III. Cell structure
• D. Cytoskeleton of protein fibers
  (microfilaments, microtubules)
  – 1.   Cell shape
  – 2.   Cell movement
  – 3.   Organelle movement
  – 4.   Cell division
          III. Cell structure
• E. Cilia and flagella are protein
  microtubule extensions of the plasma
  membrane
  – 1. Aid in movement of simple organisms
          IV. Cell function
• A. Protein assembly
• B. Metabolism

				
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posted:9/7/2011
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