7-2 Eukaryotic Cell Structure

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					7-2 Eukaryotic Cell Structure




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  Comparing the Cell to a Factory
• Many of the structures in a cell act as if they
  are specialized organs, these structures act as
  if they are specialized organs, these
  structures are known as organelles. Which
  means “little organs”.
• Cell biologists divide the eukaryotic cell into
  two major parts: the nucleus and the
  cytoplasm.

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  Comparing the Cell to a Factory
• The cytoplasm is the portion of the cell
  outside the nucleus.




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                  Nucleus
• In the same way that the main office controls
  a large factory, the nucleus is the control
  center of the cell.
• The nucleus contains nearly all the cell’s DNA
  and with it the coded instructions for making
  proteins and other important molecules.
• The nucleus is surrounded by a nuclear
  envelope composed of two membranes.

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                  Nucleus
• Chromosomes are threadlike structures
  contain the genetic information that is
  passed from one generation of cells to the
  next.
• Most nuclei also contain a small, dense
  region known as the nucleolus. This is where
  ribosomes are assembled.


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               Ribosomes
• Proteins are assembled on ribosomes.
  Ribosomes are small particles of RNA and
  protein found throughout the cytoplasm.




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       Endoplasmic Reticulum
• The endoplasmic reticulum is the site where
  lipid components of the cell membrane are
  assembled, along with proteins and other
  materials that are exported from the cell.




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            Golgi Apparatus
• The function to the Golgi apparatus is to
  modify, sort, and package proteins and other
  materials from the endoplasmic reticulum for
  storage in the cell or secretion outside the
  cell.




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                Lysosomes
• Lysosomes are small organelles filled with
  enzymes. One function of lysosomes is the
  digestion of lipids, carbohydrates, and
  proteins.




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                  Vacuoles
• Some kinds of cells contain saclike structures
  called vacuoles that store materials such as
  water, salts, proteins, and carbohydrates.




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  Mitochondria and Chloroplasts
• Mitochondria are organelles that convert the
  chemical energy stored in food into
  compounds that are more convenient for the
  cell to use.
• Chloroplasts are organelles that capture the
  energy from sunlight and convert it into
  chemical energy in a process called
  photosynthesis.

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7-3 Cell Boundaries




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          7-3 Cell Boundaries
• All cells are surrounded by a thin, flexible
  barrier known as the cell membrane.
• Many cells also produce a strong supporting
  layer around the membrane known as a cell
  wall.




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            Cell Membrane
• The cell membrane regulates what enters and
  leaves the cell and also provides protection
  and support.




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                 Cell Walls
• The main function of the cell wall is to
  provide support and protection for the cell.




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Diffusion Through Cell Boundaries
• Particles tend to move from an area where
  they are more concentrated to an area where
  they are less concentrated, this is known as
  diffusion.
• When the concentration of the solute is the
  same throughout a system, the system is at
  equilibrium.


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Diffusion of liquids




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                    DIFFUSION
Diffusion is a PASSIVE process which means no energy is used
to make the molecules move, they have a natural kinetic energy.




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Diffusion through a membrane

                             Cell membrane




  Inside cell                    Outside cell



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Diffusion through a membrane

                             Cell membrane




                   diffusion



  Inside cell                    Outside cell



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Diffusion through a membrane

                             Cell membrane




  Inside cell                    Outside cell

                  EQUILIBRIUM

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Diffusion Through Cell Boundaries
• Because diffusion depends upon random
  particle movements, substances diffuse
  across membranes without requiring the cell
  to use energy.




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                  Osmosis
• Osmosis is the diffusion of water through a
  selectively permeable membrane.
• The Effects of Osmosis on Cells




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                                  Osmosis

                                              Cell membrane
                                              partially
Sugar molecule                                permeable.




                                                     VERY Low conc.
                                                     of water
                                                     molecules. High
                                                     water potential.


VERY High conc.                                   Outside cell
                   Inside cell
of water
molecules. High
water potential.
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                                  Osmosis

                                              Cell membrane
                                              partially
                                              permeable.




                                                          Low conc. of
                                                          water molecules.
                                                          High water
                                    OSMOSIS               potential.


High conc. of
                   Inside cell                    Outside cell
water molecules.
High water
potential.
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                    Osmosis

                                Cell membrane
                                partially
                                permeable.




                      OSMOSIS




     Inside cell                    Outside cell

EQUILIBRIUM. Equal water concentration on each side.
Equal water potential has been reached. There is no net
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          Facilitated Diffusion
• Facilitated Diffusion is a fast and specific form
  of diffusion, the cell membranes have
  protein channels that act as carriers.




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Facilitated Diffusion through a
           membrane
                              Cell membrane




                                  Protein channel

   Inside cell                    Outside cell



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Facilitated Diffusion through a
           membrane
                              Cell membrane




                        diffusion




                                  Protein channel

   Inside cell                    Outside cell



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Facilitated Diffusion through a
           membrane
                               Cell membrane




                         diffusion




                                   Protein channel

   Inside cell                     Outside cell

                 EQUILIBRIUM
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Facilitated diffusion




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            Active Transport
• Active transport is a form of transportation
  that uses energy.




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Active Transport




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     Endocytosis and Exocytosis
• Endocytosis is the process of taking material
  into the cell by means of infoldings, or
  pockets, of cell membrane.
• Phagocytosis means “cell eating.”
• Many cells take up liquid from the
  surrounding environment. This is known as
  pinocytosis.


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             Phagocytosis:
• “Cell Eating”




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Phagocytosis:




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                      Pinocytosis:
•   “Cell Drinking”




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Pinocytosis:




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     Endocytosis and Exocytosis
• Many cells also release large amounts of
  material from the cell, a process known as
  exocytosis.




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                                   Direction of Osmosis

    Condition           Effect on Cell                  Net Movement of Water


External solution is
                        Cell swells and                     H2O                 H2O
hypotonic to                               Into the Cell
                       eventually bursts
cytosol




External solution is                                        H2O                 H2O
                       Cell shrinks and     Out of the
hypertonic to
                           shrivels           Cell
cytosol




External solution is
                            None               None         H2O                 H2O
isotonic to cytosol
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                  Organelles

  Organelle                          Function

Mitochondria   convert the chemical energy stored in
               food into compounds that are more
               convenient for the cell to use
Ribosome       small particles of RNA found throughout
               the cytoplasm/ Proteins are assembled
               here



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                 Organelles

  Organelle                          Function

ER            where the cell membrane is assembled


Golgi         modify, sort, and package proteins from
Apparatus     the ER for storage in the cell or secretion
              outside the cell



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                Organelles

 Organelle                          Function
Lysosome     digest lipids, carbohydrates, and
             proteins/ filled with enzymes
Nucleus      contains nearly all the cell’s DNA and
             therefore instructions for making proteins
             and other important molecules/ control
             center



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                 Organelles

  Organelle                          Function
Cell Wall     provide support and protection for the
              cell

Vacuole       store materials like water, salts, proteins,
              and carbohydrates/ saclike structures




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7-4 Diversity of Cellular Life




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       Different Organisms
• There are some organisms made up of
  just one cell this are called unicellular
  organisms.
• Uni – one……like unicycle
• Multicellular organisms have more than
  one cell. Like plants and animals.
• Multi - many

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       Levels of Organization
• Organize Organ System, Tissues, Cells, and
  Organs into the order in which they make up
  one another.
                                      Organ
   Cells     Tissue      Organ        System




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posted:3/2/2012
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