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A Tour of the Cell, cont…. Last Time : The Nucleus and the Endomembrane System Today : Other Organelles and the Cytoskeleton. Cells need energy to work. Figure 6.8 The structure and hydrolysis of ATP.
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A Tour of the Cell, cont… Last Time: The Nucleus and the Endomembrane System Today: Other Organelles and the Cytoskeleton
Chloroplasts in plant cells convert sunlight into chemical energy that will be used to make ATP
ATP is manufactured through cellular respiration that takes place in the mitochondria
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
Motor molecules like kinesin, myosin, and dynein work with the cytoskeleton to produce movement Structure of kinesin Tail Stalk Head
ATP ADP+Pi Kinesin "walks" along a microtubule track Transport vesicle ATP ADP+Pi Kinesin Microtubule
Microfilaments and Intermediate Filaments Networks of filaments near the plasma membrane help to maintain a cell’s shape
Centrosome containing a pair of centrioles Microtubules often grow out from the region called the centrosome
Cilia and Flagella move the entire cell Cilia Flagella
Cilia and Flagella have a “9 +2” arrangement of microtubule doublets Cell membrane TEM of flagella Central pair Outer doublet Dynein Microtubule doublet Spoke
The motor protein Dynein “walks” along the microtubules within the flagella on one side, causing bending Bend
Figure 7.23 A comparison of the beating of flagella and cilia
Plant cells are surrounded by cell walls made of cellulose Plasmodesmata connect adjacent plant cells
Review of an animal cell (centrioles)