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  • Why organelles? There are several reasons why cells evolved organelles. First, organelles can perform specialized functions. Second, membrane bound organelles can act as containers, separating parts of the cell from other parts of the cell. Third, the membranes of organelles can act as sites for chemical reactions. Organelles as specialized structures An example of the first type of organelle is cilia, these short filaments act as "paddles" to help some cells move. Organelles as Containers Nothing ever invented by man is as complex as a living cell. At any one time hundreds of incompatible chemical reactions may be occurring in a cell. If the cell contained a uniform mixture of all the chemicals it would not be able to survive. Organelles surrounded by membranes act as individual compartments for these chemical reactions. An example of the second type of organelle is the lysosome. This structure contains digestive enzymes, these enzymes if allowed to float free in the cell would kill it. Organelle membranes as sites for chemical reactions An example of the third type of organelle is the chloroplast. The molecules that conduct the light reactions of photosynthesis are found embedded in the membranes of the chloroplast.
  • The genes for rRNA have the greatest commonality among all living things. There is very little difference in the DNA sequence of the rRNA genes in a humans vs. a bacteria. Means that this function (building of a ribosome) is so integral to life that every cell does it almost exactly the same way. Change a base and this changes the structure of the RNA which causes it to not function.
  • accounts for 50% membranes in eukaryotic cell
  • Which cells have a lot of ER? protein production cells like pancreas = production of digestive enzymes (rough endoplasmic reticulum from a cell of exocrine pancreas (88000X))
  • Cells specialized for secretion? endocrine glands: produce hormones pituitary, pancreas, adrenal, testes, ovaries exocrine glands: produce digestive enzymes & other products pancreas, mammary glands, sweat glands
  • Ch06organelles1

    1. 1. Tour of the Cell 1 2010-2011 Tour Guide
    2. 2. Types of cells Prokaryote bacteria cells Eukaryote animal cells - no organelles - organelles Eukaryote plant cells
    3. 3. Why organelles? <ul><li>Specialized structures </li></ul><ul><ul><li>specialized functions </li></ul></ul><ul><ul><ul><li>cilia or flagella for locomotion </li></ul></ul></ul><ul><li>Containers </li></ul><ul><ul><li>partition cell into compartments </li></ul></ul><ul><ul><li>create different local environments </li></ul></ul><ul><ul><ul><li>separate pH, or concentration of materials </li></ul></ul></ul><ul><ul><li>distinct & incompatible functions </li></ul></ul><ul><ul><ul><li>lysosome & its digestive enzymes </li></ul></ul></ul><ul><li>Membranes as sites for chemical reactions </li></ul><ul><ul><li>unique combinations of lipids & proteins </li></ul></ul><ul><ul><li>embedded enzymes & reaction centers </li></ul></ul><ul><ul><ul><li>chloroplasts & mitochondria </li></ul></ul></ul>mitochondria chloroplast Golgi ER
    4. 4. Cells gotta work to live! <ul><li>What jobs do cells have to do? </li></ul><ul><ul><li>make proteins </li></ul></ul><ul><ul><ul><li>proteins control every cell function </li></ul></ul></ul><ul><ul><li>make energy </li></ul></ul><ul><ul><ul><li>for daily life </li></ul></ul></ul><ul><ul><ul><li>for growth </li></ul></ul></ul><ul><ul><li>make more cells </li></ul></ul><ul><ul><ul><li>growth </li></ul></ul></ul><ul><ul><ul><li>repair </li></ul></ul></ul><ul><ul><ul><li>renewal </li></ul></ul></ul>
    5. 5. Building Proteins 2010-2011
    6. 6. Proteins do all the work! cells DNA proteins organism Repeat after me… Proteins do all the work!
    7. 7. Cells functions <ul><li>Building proteins </li></ul><ul><ul><li>read DNA instructions </li></ul></ul><ul><ul><li>build proteins </li></ul></ul><ul><ul><li>process proteins </li></ul></ul><ul><ul><ul><li>folding </li></ul></ul></ul><ul><ul><ul><li>modifying </li></ul></ul></ul><ul><ul><ul><ul><li>removing amino acids </li></ul></ul></ul></ul><ul><ul><ul><ul><li>adding other molecules </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>e.g, making glycoproteins for cell membrane </li></ul></ul></ul></ul></ul><ul><ul><li>address & transport proteins </li></ul></ul>Do you know what organelles carry out each of these steps??
    8. 8. Building Proteins <ul><li>Organelles involved </li></ul><ul><ul><li>nucleus </li></ul></ul><ul><ul><li>ribosomes </li></ul></ul><ul><ul><li>endoplasmic reticulum (ER) </li></ul></ul><ul><ul><li>Golgi apparatus </li></ul></ul><ul><ul><li>vesicles </li></ul></ul>nucleus vesicles ribosome ER Golgi apparatus The Protein Assembly Line
    9. 9. <ul><li>Function </li></ul><ul><ul><li>protects DNA </li></ul></ul><ul><li>Structure </li></ul><ul><ul><li>nuclear envelope </li></ul></ul><ul><ul><ul><li>double membrane </li></ul></ul></ul><ul><ul><ul><li>membrane fused in spots to create pores </li></ul></ul></ul><ul><ul><ul><ul><li>allows large macromolecules to pass through </li></ul></ul></ul></ul>Nucleus What kind of molecules need to pass through? nuclear pores nuclear pore nuclear envelope nucleolus histone protein chromosome DNA
    10. 10. production of mRNA from DNA in nucleus mRNA travels from nucleus to ribosome in cytoplasm through nuclear pore 1 2 DNA Nucleus mRNA nuclear membrane small ribosomal subunit large ribosomal subunit cytoplasm mRNA nuclear pore
    11. 12. Nucleolus <ul><li>Function </li></ul><ul><ul><li>ribosome production </li></ul></ul><ul><ul><ul><li>build ribosome subunits from rRNA & proteins </li></ul></ul></ul><ul><ul><ul><li>exit through nuclear pores to cytoplasm & combine to form functional ribosomes </li></ul></ul></ul>rRNA & proteins nucleolus small subunit large subunit ribosome
    12. 13. Ribosomes <ul><li>Function </li></ul><ul><ul><li>protein production </li></ul></ul><ul><li>Structure </li></ul><ul><ul><li>rRNA & protein </li></ul></ul><ul><ul><li>2 subunits combine </li></ul></ul>small subunit large subunit 0.08  m Ribosomes Rough ER Smooth ER
    13. 14. Types of Ribosomes <ul><li>Free ribosomes </li></ul><ul><ul><li>suspended in cytosol </li></ul></ul><ul><ul><li>synthesize proteins that function in cytosol </li></ul></ul><ul><li>Bound ribosomes </li></ul><ul><ul><li>attached to endoplasmic reticulum </li></ul></ul><ul><ul><li>synthesize proteins for export or for membranes </li></ul></ul>membrane proteins
    14. 15. Endoplasmic Reticulum <ul><li>Function </li></ul><ul><ul><li>processes proteins </li></ul></ul><ul><ul><li>manufactures membranes </li></ul></ul><ul><ul><li>synthesis & hydrolysis of many compounds </li></ul></ul><ul><li>Structure </li></ul><ul><ul><li>membrane connected to nuclear envelope & extends throughout cell </li></ul></ul>
    15. 16. Types of ER rough smooth
    16. 17. Smooth ER function <ul><li>Membrane production </li></ul><ul><li>Many metabolic processes </li></ul><ul><ul><li>synthesis </li></ul></ul><ul><ul><ul><li>synthesize lipids </li></ul></ul></ul><ul><ul><ul><ul><li>oils, phospholipids, steroids & sex hormones </li></ul></ul></ul></ul><ul><ul><li>hydrolysis </li></ul></ul><ul><ul><ul><li>hydrolyze glycogen into glucose </li></ul></ul></ul><ul><ul><ul><ul><li>in liver </li></ul></ul></ul></ul><ul><ul><ul><li>detoxify drugs & poisons </li></ul></ul></ul><ul><ul><ul><ul><li>in liver </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ex. alcohol & barbiturates </li></ul></ul></ul></ul>
    17. 18. Membrane Factory <ul><li>Build new membrane </li></ul><ul><ul><li>synthesize phospholipids </li></ul></ul><ul><ul><ul><li>builds membranes </li></ul></ul></ul><ul><ul><li>ER membrane expands </li></ul></ul><ul><ul><ul><li>bud off & transfer to other parts of cell that need membranes </li></ul></ul></ul>
    18. 19. Rough ER function <ul><li>Produce proteins for export out of cell </li></ul><ul><ul><li>protein secreting cells </li></ul></ul><ul><ul><li>packaged into transport vesicles for export </li></ul></ul>
    19. 20. Synthesizing proteins ribosome cytoplasm cisternal space mRNA ribosome membrane of endoplasmic reticulum polypeptide signal sequence
    20. 21. Golgi Apparatus <ul><li>Function </li></ul><ul><ul><li>finishes, sorts, tags & ships cell products </li></ul></ul><ul><ul><ul><li>like “UPS shipping department” </li></ul></ul></ul><ul><ul><li>ships products in vesicles </li></ul></ul><ul><ul><ul><li>membrane sacs </li></ul></ul></ul><ul><ul><ul><li>“ UPS trucks” </li></ul></ul></ul><ul><li>Structure </li></ul><ul><ul><li>Stack of flattened membranes </li></ul></ul><ul><ul><ul><li>“ pita bread” like </li></ul></ul></ul>transport vesicles secretory vesicles
    21. 22. Golgi Apparatus
    22. 23. Vesicle transport vesicle budding from rough ER fusion of vesicle with Golgi apparatus migrating transport vesicle protein ribosome
    23. 24. DNA RNA ribosomes endoplasmic reticulum vesicle Golgi apparatus vesicle protein on its way! protein finished protein Making Proteins TO: nucleus TO: TO: TO:
    24. 25. Making proteins Putting it together… proteins transport vesicle Golgi apparatus vesicle smooth ER rough ER nuclear pore nucleus ribosome cell membrane protein secreted cytoplasm
    25. 28. 2010-2011 Any Questions !!