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Cell Structure and Function 2012

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					Cell Structure and Function




   Textbook Sections 7.1 and 7.3
          These cells are Neurons
            2 Ways to Make Mice
• In medieval Europe there were lots of
  mice around and farmers stored grain
  in thatched roofs barns. As a roof
  aged, it started leaking leading to
  spoiled or moldy grain.
   – Conclusion: Mice came from the
     moldy grain.
       How do you Make Frogs?
• Every spring, the Nile River flooded areas of
  Egypt, leaving behind nutrient-rich mud that
  enabled the people to grow that year's crop of
  food. However, large numbers of frogs also
  appeared.
   – Conclusion: Muddy soil gave rise to frogs
        Spontaneous Generation
• The idea that nonliving
  material can produce life
• The famous Greek
  philosopher Aristotle
  (384-322BC) believed
  insects are generated
  spontaneously from dew
  on leaves in spring, and
  mollusks formed by
  spontaneous generation
  in mud, sand, slime, or
  rock crevices
     Spontaneous Generation
• Was believed true until the mid 1600’s when
  Francesco Redi showed that maggots came
  from flies not meat
                      Before Microscopes
• People believed in spontaneous generation
• People believed that diseases were caused
  by spirits and curses
• Microorganisms, such as bacteria, were
  never thought of as a cause of diseases

                        Legionella
                                            Anthrax




Intestinal Bacteria                  MRSA
           Early Microscopes
• Anton van Leeuwenhoek invented a simple
  light microscope in the 1600’s with one lens
• Using his microscope was the first person to
  discover microorganisms in water
• This was very
  important in the
  discovery of what
  caused diseases &
  illnesses from drinking
  contaminated water
           Light Microscopes
• Microscopes were improved
  with higher quality lenses
  and multiple lenses and
  resulted in the compound
  light microscope similar to
  the ones we use
• Objects can be multiplied up
  to 1500 times
• Uses light to illuminate the
  object being viewed
             Discovery of Cells
• 1665 Robert Hooke examined cork with a
  compound microscope & found it to “perforated &
  porous” & made of “many little boxes”
• He then looked at stems of trees, carrots & ferns
  & found similar “little boxes” that reminded him of
  the small rooms that monks lived in called cells.
 Other Scientists Added Their Discoveries
• 1830’s Matthias Schleiden observed that plants
  are made of cells
• Theodor Schwann found animals are made of cells
• Rudolf Virchow reasoned that cells only come from
  other cells




                                          Ameoba
                   Embryonic Stem Cells
                 Cell Theory
Putting the four scientists discoveries together
gave us the Cell Theory
1. All organisms (plants and animals) are composed of
   one or more cells (Schleiden and Schwann)
2. The cell is the basic unit of structure and
   organization of organisms (Hooke)
3. All cells come from preexisting
   cells (Virchow)
    Electron Microscopes
• Developed in the 1930’s
• Uses a beam of electrons to magnify
  up to 500,000 times
• 3 types
  – SEM – scanning electron microscope
    – shows 3-D surfaces
  – TEM – transmission electron
    microscope – allows the cell’s interior   Virus
                                              Dust mite
    to be seen
  – STM – scanning tunneling microscope
    – creates computer images of the
    surface atoms
      What are these?

• Pollen Grains
Sand magnified 250x
Dust
Butterfly Eggs
Mosquito Head
Eyelashes
Frost
     Two Different Cell Types
• Prokaryotic cells do not contain membrane-
  bound organelles, are mostly unicellular & small
  – Eubacteria and Archaebacteria
• Eukaryotic cells have membrane-bound
  organelles and are mostly multicellular
  – Plant
  – Animal
  – Fungus
  – Protists
            Prokaryotic Cells
• No nucleus – DNA floats free in the cytosol
• Flagella for movement
• Pili for reproduction and attachment
 Plant &
Animal Cell
Organelles
       You are built out of cells!!!
• Atoms  elements  molecules  organelles  cells
   tissues  organs organ system  organism
• Your cells make new cells
• 200 million new cells per
  minute!
• 300 billion new cells EVERY
  DAY!!
Some types of cells your body makes
          • Leader of the cell
Nucleus   • Contains directions
            to make proteins
            which all cell parts
            depend upon
          • Contains
            chromatin–
            strands of genetic
            material
          • Largest membrane
            bound organelle
          • Surrounded by
            Nuclear Membrane
            and perforated with
            nuclear pores
            Chromatin
• Master set of directions for making
   proteins
• During cell division, chromatin condenses
   to make chromosomes
• Strands of DNA
 - the genetic
   material
             Nucleolus
• Found inside
  the nucleus
• Produces
  ribosomes
• Is a
  combination of
  DNA and
  proteins
• Condenses
  into
  chromosomes
             Ribosomes
• Ribosomes produce proteins following
  directions from the DNA
• Ribosomes do NOT have a membrane
  – made of RNA and protein
  – Ribosomes must leave the nucleus to make
    proteins in the cytoplasm
 Rough Endoplasmic Reticulum
• Site of all chemical reactions
• Series of folded membranes
• Folding allows a large amount to fit in a
  small space
• Ribosomes are
  attached to the
  surface of the
  Rough ER & they
  synthesize protein
  – Proteins are either
    exported from the
    cell or inserted into
    the cell membrane
         Nuclear
         Membrane

Smooth
                       Cell
                     Membrane




           Vesicle



TRANSPORT ORGANELLES
           Golgi Apparatus
• Sorts, packages and
  secretes
• Proteins are transferred to
  the Golgi Apparatus after
  being made by the
  ribosomes on the Rough ER
• System of membranes that
  looks like a stack of
  pancakes
• Sorts proteins and packages
  them into membrane bound
  vesicles
• Like sorting mail at the post
  office
                  Vesicles
• Pinch off from the Golgi Apparatus
• Transportation bubble for proteins and other
  large molecules
                        Golgi Apparatus




                      Vesicles
               Lysosomes
• Membranous sacs of digestive enzymes
• Lysosomes break down cellular materials
  and worn out cell parts
• Transport into and
  out of cell
• Common in animal
  cells, rare in plant
  cells
• Create fingers on
  human embryos by
  digesting the web
  between the fingers
                 Cytoplasm
• Clear, gelatinous
  fluid inside cell
  that suspends all
  of the organelles
  (organelles float in
  cytoplasm)
• Ribosomes and
  RNA enter the
  cytoplasm through
  nuclear pores in
  the nuclear
  membrane
             Cell Membrane
• Allows selected
  materials to pass
  into and out of the
  cell
• Made of
  phospholipids
• All cells have cell
  membranes
          Nuclear Envelope
• Nuclear
  Envelope is a
  double
  membrane
  made of 2
  phospholipid
  bilayers
  – Ribosomes
    and RNA
    pass through
    nuclear
    pores
      Smooth Endoplasmic
          Reticulum
• Smooth ER has
  no ribosomes
  attached and
  produces and
  stores lipids
• Involved in
  chemical
  regulation
REPRODUCTION ORGANELLE
                  Centrioles
• Used to move
  chromosomes
  during cell
  division
• Only found in
  animal cells
ENERGY ORGANELLES
                    Chloroplasts
• Found in plants, algae, and
  some protists
• Capture sunlight and
  converts that energy to
  chemical energy
• Has a double membrane
• Stacks of individual
  thylakoids form grana and
  they trap the suns energy
• Contain chlorophyll – light
  energy trapping pigment
             Mitochondria
• Membrane bound
  organelles in plant and
  animal cells
• Provides energy for cell
  usage
• Highly folded inner
  membrane
• Number of mitochondria
  in a cell depends on
  cells function
  – Muscles have more than
    skin cells because they
    need more energy
STRUCTURE AND MOVEMENT
ORGANELLES
                  Cell Wall
• An inflexible barrier
  that protects the cell
  and gives it support
• Found in plants, fungi,
  bacteria, and some
  protists
• Located OUTSIDE the
  plasma membrane
• Composed of cellulose
  (a carbohydrate)
• Porous allowing
  molecules to enter
       Vacuoles and Storage
• Membrane bound
  compartment
• Temporary storage
  for water and other
  materials
• Provides structural
  support for the cell
• Found mostly in
  plant cells (not in
  many animal cells)
               Cytoskeleton
• System of structure
  and support
• Skeleton of tiny rods
  and filaments
• Microtubules are
  thin, hollow cylinders
  made of protein
• Microfilaments are
  smaller, solid protein
  fibers
                         Cilia
• Short, numerous,
  hairlike organelles
  made of microtubules
• Function in movement
• Extend from cell’s
  surface
• Found in eukaryotic
  and prokaryotic cells
  – Present in the lining of
    human respiratory
    tracts
                   Flagella
• Long, whip-like, less
  numerous extensions
  from the cell’s
  surface
• Function in
  movement
ORGANELLES UNIQUE TO
PLANTS OR ANIMALS
Animal Cell




       Vesicle

				
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posted:1/5/2013
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