Cells

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					Cells
                           Cells
• Robert Hooke was the first person to observe
  cells in 1665
• Cell Theory
    – All living things are made of at least one cell
    – Cells are the basic unit of structure and function of all
      organisms
    – Cells only come from other living cells
•   Cytology: study of cells
•   Contain organelles: small structures in the cell
•   Eukaryote: has a nucleus, ex. Human cells
•   Prokaryote: lacks a nucleus ex. bacteria
                      Types
• Prokaryote:
  –   No nucleus
  –   No membrane bound organelles
  –   Smaller, less complex
  –   Ex. Bacteria
• Eukaryote
  –   Nucleus
  –   Membrane bound organelles
  –   Larger, more complex
  –   Ex. Plants, animals, etc.
            Cell Membrane
• Made of a phospholipid bilayer and
  surrounds the cell
• Living portion of the cell
• Functions
  – Protect the cell
  – Support the cell and give it shape
  – Control passage into and out of the cell
                  Cell Wall
• Nonliving portion found in some cells
  (plants)
• Outside the cell membrane
• Made of cellulose (carbohydrate)
• Function
  – Protects the cell and gives it shape
                     Nucleus
• Large circular structure
  usually in the center of
  the cell
• Surrounded by a nuclear
  membrane which is a
  double layer
• Contains DNA, genetic
  information
• Contains a nucleolus
  which makes RNA
               Cytoplasm
• All the living substance in a cell except the
  nucleus
• Most of the cell is cytoplasm
• Jelly like substance
• Holds the organelles in place
              Mitochondria
• “Powerhouse” of the
  cell
• Break down glucose
  to make energy in the
  form of ATP
• Surrounded by a
  double membrane
      Endoplasmic Reticulum
• Folded membranes
  that form a
  passageway
  throughout the
• Rough ER has
  ribosomes attached to
  it which make
  proteins
• Smooth ER lack
  ribosomes and
  transport lipids
                Vacuoles
•   Membranous sac
•   “Storage bins”
•   Waste vacuoles
•   Food vacuoles
               Ribosomes
• Make proteins
• Some are “free
  floating” in the
  cytoplasm
• Others are attached
  to rough endoplasmic
  reticulum
• Made of two subunits
                 Centrioles
• Two rod shaped
  organelles near the
  nucleus of animal
  cells
• Only function during
  cell reproduction
• Form a spindle to
  separate
  chromosomes
              Lysosomes
• Contains hydrolytic
  or digestive
  enzymes
• Numerous in white
  blood cells
• Single membrane
• Only in animal cells
           Golgi Apparatus
• Flattened
  membranes
• Form channels
• Package
  secretions for
  export
• Secretion vesicles
  break off the end
        Plant vs. Animal Cells
• Plant Cell
  – Cell wall makes it
    rectangular
  – Contains chloroplasts
    (chlorophyll)
  – Larger vacuoles
• Animal Cell
  – No cell wall making it
    oval
  – No chloroplasts
  – Contains centrioles
              Organization
• Cells: Basic unit of structure and function
• Tissue: Group of cells working together for a
  similar function, ex. Skin, blood
• Organ: Group of tissues working together for a
  similar function, ex. Liver, stomach
• System: Group of organs working together for a
  similar function, ex. Digestive, nervous
• Organism: Complete living thing, ex. Human,
  amoeba
           Cell Processes
• Diffusion: movement of molecules from an
  area of high concentration to an area of
  low concentration
• Osmosis: diffusion of water
• Regulated by the cell membrane
Respiration and Photosynthesis
• Cellular Respiration: process by which food
  molecules are broken down for energy
  – Glucose is broken down into water, carbon dioxide,
    and energy
     C6H12O6 + O2  H2O + CO2 + energy
• Photosynthesis: process by which cells energy
  is converted to chemical energy in the form of
  glucose
  • Occurs on membranes of the chloroplasts
    CO2 + H2O + energy  C6H12O6 + O2
                    Mitosis
• Mitosis: Asexual reproduction resulting in two
  identical cells
  – Interphase: DNA doubles and forms pairs
  – Prophase: nuclear membrane and nucleolus
    disappears, spindle forms, chromosomes form
  – Metaphase: chromosomes line up at the equator
  – Anaphase: chromosomes separate and one copy
    moves toward each pole
  – Telophase: cell membrane begins to pinch and two
    new daughter cells form.
                 Meiosis
• Separation of chromosomes during the
  formation of gametes (sex cells)
• Similar to mitosis but DNA replicates once
  and divides twice
• Creates four daughter cells with half the
  number of chromosomes

				
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posted:3/23/2012
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