a tour of the cell cont n.
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A Tour of the Cell, cont…

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  1. A Tour of the Cell, cont… Last Time: The Nucleus and the Endomembrane System Today: Other Organelles and the Cytoskeleton

  2. Cells need energy to work

  3. Figure 6.8 The structure and hydrolysis of ATP

  4. Chloroplasts in plant cells convert sunlight into chemical energy that will be used to make ATP

  5. ATP is manufactured through cellular respiration that takes place in the mitochondria

  6. Peroxisomes

  7. The cytoskeleton

  8. 3 types of cytoskeletal structures Intermediate filaments Microtubules Microfilaments Protein subunits Actin a-tubulin andb-tubulin dimers Keratin, others Fibers wound into thick cables Two intertwined strands Hollow tube Structure 7 nm 10 nm 25 nm Actin subunit Keratin subunits Tubulin dimer Functions • maintain cell shape by resisting compression • maintain cell shape by resisting tension • motility via flagella/cilia • motility via pseudopodia • anchor nucleus and some other organelles • move organelles • muscle contraction • cell division in animals • move chromosomes during cell division

  9. Motor molecules like kinesin, myosin, and dynein work with the cytoskeleton to produce movement Structure of kinesin Tail Stalk Head

  10. ATP ADP+Pi Kinesin "walks" along a microtubule track Transport vesicle ATP ADP+Pi Kinesin Microtubule

  11. Microfilaments and Intermediate Filaments Networks of filaments near the plasma membrane help to maintain a cell’s shape

  12. Microfilaments aid in motility

  13. Centrosome containing a pair of centrioles Microtubules often grow out from the region called the centrosome

  14. Cilia and Flagella move the entire cell Cilia Flagella

  15. Cilia and Flagella have a “9 +2” arrangement of microtubule doublets Cell membrane TEM of flagella Central pair Outer doublet Dynein Microtubule doublet Spoke

  16. The motor protein Dynein “walks” along the microtubules within the flagella on one side, causing bending Bend

  17. Figure 7.23 A comparison of the beating of flagella and cilia

  18. Plant cells are surrounded by cell walls made of cellulose Plasmodesmata connect adjacent plant cells

  19. Animal cells are connected through Intercellular junctions

  20. Review of an animal cell (centrioles)

  21. Review of a plant cell