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THE CELL

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					  THE CELL
 Breaks down macromolecules
 Releases energy from food
 Synthesis of cell parts
 Produces proteins
   1st Cells Examined
 1600’s Anton van Leeuwenhoek
 1665 Robert Hooke
 1830’s Schleiden & Schwann
    CELL THEORY
   17TH Century to 1830’s
   3 Main Ideas
    1.   All organisms are composed of 1
         or more cells.
    2.   Cell is basic unit of organization.
    3.   All cells come from pre-existing
         cells.
 TWO BASIC CELL TYPES

DEPENDING ON THEIR
INTERNAL ORGANIZATION
PROKARYOTIC
 Organism with a cell that
  lacks internal structures
  surrounded by membranes.
 Most are single celled
  organisms.
EUKARYOTIC
 Organism that has cells
  containing internal
  membrane-bound
  structures/organelles.
 Single or many cells.
ORGANELLES
 Enclosed by a membrane
  isolating it from the rest of
  the cell.
 Largest = Nucleus
     EUKARYOTIC CELL
       STRUCTURES

   Boundaries and Control
Plasma Membrane-Boundary
between cell and the external
environment.
   2 layers: Lipid and Protein
   Controls movement of materials
    in and out of cell.
   Helps chemical balance.
   Flexible
Cell Wall-External boundary
outside the plasma membrane.
 Relatively inflexible structure
 Plants, Fungi, and most
  Bacteria
 Plant cell walls contain
  cellulose molecules
Nucleus- Organelle that
manages cell functions.
 Contains DNA
 Surrounded by a Nuclear
  Envelope
Nuclear Envelope
 Attachment sites for DNA
  organization
 Outer surface has Ribosomes
 Large pores for materials
  transportation
Chromatin- Long tangled
strands of DNA
   Forms chromosomes
Nucleolus-Region that
produces tiny cell particles
involved in protein synthesis.

 Contains RNA
 Produces ribosomes
RIBOSOMES:
 Site where the cell assembles
  enzymes and other proteins.
 Considered organelles but
  are not bounded by a
  membrane.
Assembly, Transport, and Storage
 A major function of most cells
  is to make proteins and other
  materials.
 Many cells are involved in
  protein synthesis.
 Also involved in storage of
  materials.
Cytoplasm: Material that lies
outside the nucleus and surrounds
the organelles.
   Most of assembly and storage
    takes place (protein assembly)
   Clear, gel-like fluid
   Makes up more than half the
    volume of a typical animal cell
Endoplasmic Reticulum:folded
membrane that forms a network
of interconnected compartments.
   Occupies most of the cytoplasm
   Provide a large surface area where
    chemical reactions take place
   Contains enzyme for lipid synthesis
   Rough ER vs. Smooth ER
   Functions as cell’s delivery system
   Protein Assembly (ribosomes)
     Structures for Storage
   Golgi apparatus- A series of closely
    stacked, flattened membrane sacs that
    receives newly synthesized proteins and
    lipids from the ER and distributes them
    to the plasma membrane and other cell
    organelles.
   Vesicles- Small membrane bound
    transport packages that transfer protein
    from ER to Golgi apparatus.
    Structures for Storage (cont.)
   Vacuole- Sac of fluid surrounded by
    a membrane used for temporary
    storage.
      Single celled organisms = specialized
     Plants = 1 large vacuole
     Animals = many smaller vacuoles
    (store food, enzymes, & sometimes
       waste products)
    Structures for Storage (cont)
   Lysosomes-Organelles that contain
    digestive enzymes
       Digest excess or worn out cell parts
       Digest food particles
       Invade viruses and bacteria
               Organelles that
              Transform Energy
   Mitochondria – organelle in which
    food molecules are broken down to
    release energy. (Powerhouse of the cell)
       Found in every cell in varying numbers
        (Liver = 2500/cell)
       Rod shaped
       Inner membrane forms Cristae (long
        narrow folds) where energy storing
        molecules are produced.
      LYSOSOME
RICH DIGESTIVE ENZYME
 USED TO BREAKDOWN
 FOOD AND MATERIAL.
Clean up crew
         VACUOLE
Storage bubble. Holds food,
 materials, and waste.
Enters through ENDOCYTOSIS
Exits through EXOCYTOSIS
  PLASTIDS-Plant organelles
  used for storage.
 Storage of:
     Starches
     Lipids
     Pigments
       Named according    to their color or
       pigment they contain.
         Green of leaves

         Bright colors of flowers and fruits
Chloroplasts- organelles of
green plants that transform
light energy directly into usable
chemical energy and store that
energy in food molecules.
   Chlorophyll- A green pigment that
    traps the energy from sunlight.
Structures for Support
   Cytoskeleton- A network of thin,
    fibrous elements that provide
    support for organelles.
       Microtubules- thin, hollow cylinders
        made of protein
       Microfilaments- thin, solid protein
        fibers
Structures for Movement
   Cilia- short, numerous, hairlike
    projections out of the plasma
    membrane.
       Occur in large numbers on cell’s
        surface
       Found in upper respiratory tract
Structures for Movement cont.
   Flagella – Long, threadlike
    structures that move with a
    whiplike motion.
       Sperm cells
      Cellular Organization
Unicellular = Single-celled
 organisms
     All metabolic functions
      preformed by a single
        Cellular Organization cont.
   Multicellular = Many celled
    organisms.
       Specialized to perform distinct
        metabolic functions.
       Cell depend on each other to
        carry out life functions
         Multicellular Organization
   TISSUE = Group of cells function
    together to perform an activity
       Cell junctions = contact sites
        between adjacent cells
         Anchor cells  together
         Allow cells to communicate

       Muscle and nerve tissues
       Stems and roots
Cellular Organization cont.
   Organs = Groups of two or more
    tissues that function together.
       Stomach
       Leaves
Cellular Organization cont.
   Organ System = A group of
    organs that work together to
    carry out major life functions.
       Nervous system
       Flower of a plant

				
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