Cell Structure and Function Powerpoint

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					  Cells
Structure and
   Function
 Unit 1: Section 3
  Characteristics of Life
• Movement:
  – Animals - Walking, running, crawling
    swimming, etc
  – Plants/Flowers - open and close, flowers
    and leaves bend towards the sunlight.
• Response: Animals and plants both
  respond to stimulus. Stimulus is a
  change within their
  environment. Animals run away from
  predators. Some plants loose their
  leaves when the days shorten.
• Energy: Both plants and animals
  require energy to grow and
  mature. Animals eat vegetation
  (herbivores) or other animals
  (carnivores).
  – Animals are known as heterotrophs
    because they do not make their own
    food.
  – Plants have the ability to turn carbon
    dioxide and water into sugars by
    photosynthesis. They are known as
    autotrophs.
   Characteristics of Life
• Excretion: The by-products of
  the food that plants and animals
  use must be removed from the
  organism. This can be carbon
  dioxide gas, water vapor, oxygen
  or solid waste.
• Metabolism: The ability of cells
  to obtain energy and carry out
  activities that is important to the
  cell.
• Water Requirements: Over 70% of
  a cell is water and all the activities that
  a cell carries out must be done in a
  liquid medium.
• Organic Compound Production:
  The kinds of chemicals made by cells
  are all organic compounds. They are
  large complex molecules that have
  carbon as the main atom.
Characteristics of Life
 • Growth and Development: As a cell
   grows it makes and adds new substances to
   itself. Multicellular organisms will do a
   similar thing as they grow.
 • Reproduction and Inheritance:
   Reproduction is the process by which
   organisms produce more of their own
   kind. Inheritance is passing of
   characteristics from one generation to the
   next.
 • Adaptation: An existing structure or
   behavior that contributes to the survival of
   an organism in a particular environment
       Structures in the Cell
    As we have already seen the cell is the basic
    unit of life. Each cell is fully functional and
    must obtain, create and maintain various
    complex molecules in order to survive. Cells
    must carry out the characteristics that
    define a living thing. They include:
•   Obtain food and energy
•   Convert energy from food into complex
    molecules that can be used by the cell
•   Construct and repair damaged or worn out
    parts (organelles).
•   Carry out chemical reactions.
•   Eliminate waste products.
•    Reproduce.
•   Keep records of how to build structures.
Cell Size
Prokaryotes and Eukaryotes
• All cells can be classified as either
  Prokaryotes or Eukaryotes.
Prokaryotes

 • They are the smallest living cells with
   a relatively simple internal structure.
 • All bacteria are prokaryotes.
 • They do not contain a nucleus and the
   genetic material (DNA or RNA) is
   contained in an area known as a
   nucleoid.
 • The word prokaryotes is derived from
   (pro) before and (karyon) nucleus.
Prokaryotic Cell
Eukaryotes

• The cells are larger and have more complex
  parts.
• Plants, Animals, Fungi, and Protists are
  composed of eukaryotic cells.
• The genetic material (DNA and RNA) is
  contained in the nucleus of the cell.
• The word eukaryote is derived from (eu) true,
  and (karyon) nucleus.
  Typical Eukaryotic Cell




Organelles
      Small bodies that have a specific
      structure and function
Cell Membrane
                • The structure that
                  separates the inside
                  of a cell from its
                  environment.
                • Semi-permeable
                  membrane that
                  allows substances to
                  pass into and out of
                  the cell.
The Cytoplasm
• Fluid /gel-like substance found inside
  the cell membrane, composed mostly of
  water, and contains dissolved materials.
• Provides a medium for many chemical
  reactions that occur within the cell.
• Suspension medium for the all other
  organelles.
Nucleus
• The largest and most prominent organelle
  within the cell. Size varies but about 5
  microns.
• Contains the genetic material (DNA) which is
  the blueprint for the cell.
• It is the command center of the cell as it
  regulates all functions of the cell.
• It has a double layer membrane to separate
  its comtents from the cytoplasm.
Nucleus Pictures
Inside the nucleus
Nuclear Pores
• Pores in the nuclear membrane large enough
  to allow macromolecules to enter and
  ribosomes to leave the nucleus.
Chromatin
• Genetic material in its uncoiled state. It
  spends most of its existence like
  this. Changes take place when the cell starts
  to divide.
Nucleolus
• Area within the nucleus that contains the
  chromatin.
• It functions as an area which produces the
  compounds for the production of the
  ribosomes needed within the cell.
Ribosome
• Tiny organelles responsible for production of
  proteins within the cell.
• Structurally it consists of a large and small
  subunit.
• Cytoplasmic ribosomes (free ribosomes) are
  used to help produce proteins used within
  the cell (mainly enzymes)
• Ribosomes attached to the endoplasmic
  reticulum produce proteins that are
  processed within the endoplasmic reticulum
  and sent to the golgi apparatus via vesicles.
Pics of Ribosomes
Mitochondria
• This is a double
  layered organelle
  with the inner layer
  highly folded. The
  outer layer
  separates the
  chemical reactions
  that occur inside the
  mitochondria from
  the cytoplasm.
  Mitochondria (con’t)
• The folds of the cristae, (inner layer) carry
  out the process of converting ADP + P into
  ATP. This is a complex process involving
  many different enzymes.
• Mitochondria have the ability to create new
  ones by dividing themselves without the
  entire cell carrying out cell division. They
  have their own strand of DNA that is
  responsible for this.
• The number of mitochondria in a cell
  depends upon the amount of energy the cell
  requires to use.
Vesicle
          • They are small
            membrane bound
            structures used to
            transport
            macromolecules
            throughout the cell
            or out of the cell.
         The Endomembrane System

The Endoplasmic Reticulum

The Golgi Apparatus

Lysosomes

These components act to package materials for

transport within the cell and provide a place for

specialized chemical reactions.
Endoplasmic Reticulum (ER)

 -Compartmentalizes the cytoplasm –
 like a separate factory of chemicals
 and transports them around the cell
 -Increases surface area (due to
 folding) available for biochemical
 synthesis

  Smooth ER
  Synthesis of fatty acids and phospholipids
   Rough ER
   Studded with ribosomes
   Sites for translation of genetic
   information into proteins
                   Lysosomes
     Contain hydrolytic digestive enzymes




Have enzymes for digesting many different
molecules – digests used and worn out organelles
and other substances –garbage collector of the cell

    Tay Sachs Disease
Golgi Apparatus
• The vesicles that come from the ER fuse
  with the disk like structures that make up
  the golgi apparatus and completes the
  synthesis of the macromolecules making
  them fully functional.
• Also it keeps these molecules separate from
  the cytoplasm.
• Packaged molecules are sorted and then
  sent off to wherever they are needed.
• Molecules leaving the cell are pinched of in
  vesicles from the golgi apparatus and sent
  out of the cell.
• Membranes that make up the vesicles are
  recycled, incoming vesicles replace outgoing
  ones.
The Cytoskeleton

Actin Filaments

Microtubules

Centrioles

Cilia and Flagella
Cytoskeleton maintains cell shape and
causes cell and organelles to move.




                      Cytoskeleton is dynamic
              Microtubules


Small, hollow cylinders made of tubulin, a
globular protein

In many cells, microtubule assembly under
control of centrosome, the microtubule
organizing center
                Centrioles

Centrioles are short cylinders having nine sets
of triplets with none in the middle
(9 + 0 pattern)

Involved with centrosomes
     Centrosomes function to
     organize the mitotic spindle

      Plant cells have centrosomes
      but not centrioles

Give rise to basal bodies that direct organization
of microtubules within cilia and flagella
   Cilia and Flagella
• Cilia generally appear as small hair like
  structures that surround the body of small
  single-celled organisms. It is also found on
  many specialized cells in multi-cellular
  organisms.
• Wave motions of these structures cause the
  organism to move.
• Flagella are similar to cilia but longer. Most
  organisms would have one or two
  flagella. Some organisms have more!
• Sperm cells contain single flagella.
             Cilia and Flagella
Cilia shorter than flagella

Give movement ability to cells




            Paramecium (cilia)
            Sperm (flagella)
            Respiratory Tract (cilia)
In Plant Cells Only
   Cell Wall
• Found around plant and fungal cells. Also
  found in some single celled eukaryotic
  organisms.
• Consists mostly of cellulose fibers with
  relatively large spaces between the fibers.
• Cell wall does not control what passes
  through the cell but rather adds rigidity to
  the cell and plays an important role in
  preventing cells from bursting in a hypotonic
  environment.
Cell Wall
Chloroplasts

   Found in plants, algae, and some protozoans

   Photosynthesis
    Solar energy + CO2 + H2O - C6H12O6 + O2
                                  Vacuoles

                             Prominent in plant
                             cells where they’re
                             filled with a watery
                             fluid that gives
                             support to cell

                             Vacuoles store
                             substances

Water, sugars, salts, pigments, toxic molecules


This large vacuole is filled with liquid and plays
an important role in the rigidity of the cell.
Plastids

• The most common plastid is chloroplast
  that contains the pigment chlorophyll.
• The chlorophyll is contained within
  stacked membranes and this is the site
  of photosynthesis.
Plant vs. Animal Cells

				
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posted:8/12/2011
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