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					 CELLS
CELLULAR COMPONENTS
     & PROCESES
     MODERN CELL THEORY
1.   The cell is the unit of structure and
     function in living things.
2.   All cells arise from preexisting cells.
3.   The cells of all living things carry on
     similar chemical activities.
4.   All cells carry on their metabolic
     activities in organelles.
 There are two types of cells:
1.   Prokaryotic- cells that DO NOT have
     a nucleus or other cell ORGANELLES
2.   Eukaryotic- cells with a NUCLEUS &
     cell ORGANELLES

    Which is more complicated?
    REMEMBER YOU ARE EUKARYOTIC!
   The parts of a cell that carry out a
    function are called cell ORGANELLES:
   All cells have the following
    organelles:
     Cell Membrane
     Cytoplasm

     Ribosomes

     Cytoskeleton
Eukaryote cells ALSO have:
   Nucleus
   Nucleolus
   Mitochondria
   Golgi Body Complex
   Endoplasmic Reticulum
   Vacuole
   Lysosome
   Centrioles (ANIMAL ONLY)

Only Plant Cells have all of the above &:
  Cell Wall
  Chloroplast
organelles
 little “organs” of the cell
 Organelles are present in BOTH
  plants and animals
 Carry out cellular functions!
Nucleus
   cellular control center
       Controls cellular activity
 contains hereditary material
  (DNA in chromosomes)
 self duplicating structure -
  divides when the cell divides
Nuclear membrane
   surrounds nucleus allowing
    certain materials to enter and
    leave
Nucleolus
 round organelle in the nucleus
 usually a pair

 involved with the synthesis of
  RNA in the ribosomes
Ribosomes
 sites of protein synthesis in the
  cytoplasm
 may be free in the cytoplasm or
  attached to the endoplasmic
  reticulum
Endoplasmic reticulum (ER)
 cytoplasmic channels from the
  cell membrane to the nuclear
  membrane
 associated with the storage,
  synthesis, and transport of
  materials within the cell
 “HIGHWAY” for cell transport
Cytoplasm (protoplasm)
 fluid like material between the
  cell membrane and the nucleus
 over 80 % water

 “HOLDS” cell organelles in place

 site of most organelles and
  cellular chemical reactions
    Vacuole
 membrane bound cytoplasmic
  spaces containing materials
 ** Vacuoles are crucial in single-
  celled organisms
Two Types:
     Food vacuole--store and digest
      ingested food
     Contractile vacuole-pumps excess
      water from cells maintaining
      homeostasis
Lysosome
 pouch containing digestive
  enzymes
 digest bacteria and some foods
  entering the cell
 Breaks down complex molecules
  into simpler molecules (SLICE)
 breakdown worn out cell
  organelles
 Mitochondrion
 "Powerhouse of the cell"
 carries on cellular respiration
  (contains respiratory enzymes that
  make ATP) (energy molecule)
 may contain DNA--is self
  duplicating-- divides when the cell
  divides
 found in greater #s in active cells
Golgi apparatus (complex)
 usually located near the nucleus
 synthesizes, packages, and
  secretes cellular products
 Packages waste & harmful
  materials
     Plasma (cell) membrane
   The cell membrane is SEMI-PERMEABLE
   selectively regulates the flow of materials
    to and from the cell--thus maintaining
    chemical homeostasis within the cell
   The membrane acts like a BOUNCER only
    allowing certain things in and out of the
    cell It is made up of a lipid bilayer
   double layer of FAT - "Fat sandwich"
   transport through the plasma membrane
    likely occurs through these globular
    proteins (Fluid mosaic model)
   Hydrophilic- attracts water
   Hydrophobic- repels water

   Why is it important that the cell
    membrane is made up of small
    phospholipids?
ANIMAL CELL ORGANELLES ONLY

  Centriole- a cylindrical structure
   found in the cytoplasm which
   appears to function during the
   division of certain animal cells
   (usually near the nucleus)
  Helps animal cells divide
PLANT CELL ORGANELLES ONLY
   Cell Wall- a nonliving structure
    which surrounds and supports the
    cell - composed mostly of cellulose
       Gives the plant cell structure &
        support
   Chloroplasts- green in color-double
    membrane - contain the green
    pigment chlorophyll which carries
    on photosynthesis
       Uses the sun’s energy to make food
        for the plant
photosynthesis
 the conversion of light energy to
  chemical energy by chlorophyll
  in chloroplasts
 Overall Net equation for
  photosynthesis:
       6 Water + 6 Carbon dioxide yields
        glucose + 6 oxygen (when
        catalyzed by chlorophyll in the
        presence of sunlight)
Levels of Tissue Organization
  cell - unit of structure of all life
  tissue - composed of groups of
   similar cells
  organs - composed of groups of
   tissues functioning together
  organ systems - composed of
   groups of organs functioning
   together
    Types of transport in Cells
 Passive transport - movement of
  substances through a membrane
  from a region of high to a region of
  low concentration - no energy
  needed (ATP) - diffusion and
  osmosis are examples of this
 Active transport - movement of
  substances through a membrane
  from a region of low concentration
  to a region of high concentration -
  requires cellular energy (ATP)
   Whether passive or active transport
    is needed depends on the
    CONCENTRATION GRADIENT
   The concentration gradient is the
    difference in the concentration of a
    substance in two different spaces
   Concentration - the amount of a
    particular substance in a contained
    area compared with the amount of
    the same substance in another area
   Translation: Amount of something in
    a space (water, salt, sugar, iron,)
PROCESSES OF THE PLASMA
MEMBRANE
 There are two types of passive
  transport: Diffusion and
  Osmosis
 The goal of both diffusion and
  osmosis is to reach
  EQUILIBRIUM within the cell
 Equilibrium is a condition in
  which the movement in one
  direction is equal to the
  movement in another direction
Diffusion
 the tendency of molecules to
  move from an area of higher
  concentration to an area of
  lower concentration
 (concentration gradient- diff in
  conc. between 2 regions)
    Osmosis
   movement of water through a membrane
    from a region of higher to lower con.
   Solute - substance being dissolved in a
    liquid (ex. salt)
   Solvent - substance doing the dissolving
    (ex. water)
   Permeability - the extent to which a
    membrane will allow particular sized
    molecules to pass
   Semi-permeable membrane (selectively
    permeable)-allows some molecules to pass
    but not others
   So, describe how “Kool-Aid”® is
    made with regard to the terms
    “solute” and “solvent”. What is the
    “universal solvent”?
   When comparing two solutions there are
    three possible relationships, We Identify
    the relationships by determining what
    would happen if a cell were placed in the
    solution.
   Hypertonic- A solution that causes a
    cell to shrink because of osmosis.
    Meaning water leaves the cell.
   Hypotonic- A solution that causes a cell
    to swell because of osmosis meaning
    water rushes into the cell.
   Isotonic-A solution that causes no
    change in cell size. Meaning there is no
    movement of water.
  If the fluid outside     Then the outside   Water moves…   Effect on the cell?
      the cell has…           fluid is…


…less water than is
present inside the cell



…more water than is
present inside the cell



…same amount of
water as inside the cell
   So, answer this question…. Why do
    “establishments” offer free popcorn,
    peanuts, and pretzels to their
    patrons if they are serving
    beverages? What changes are
    taking place in the body to initiate
    the need for more beverages?
Active Transport-
 the movement of a substance
  against the concentration
  gradient. (uphill)
 Active transport requires cell to
  USE ENERGY
   Sodium pump - transports three
    sodium ions out of the cell and
    two potassium ions into the cell
   Both are against the
    concentration gradient
   The energy needed to perform
    this activity is supplied by ATP
    (adenosine tri-phosphate)
   ATP is a unit of energy made by
    the cell
   Endocytosis- the movement of a
    substance into the cell by a vesicle. A
    vesicle is a form of packaging that is
    used by cells.
   Exocytosis- the movement of a
    substance out of the cell by a vesicle.
   Phagocytosis- cytoplasm of cell
    surrounds and engulfs particle--ex.
    ameba and white blood cell
   Pinocytosis- plasma membrane
    "pinches in" to permit entry of molecules
    too large to diffuse through

				
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posted:6/7/2010
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