Download - Cell Cytoskeleton
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AP Biology
2005-2006
Chapter 7. The Cell:
Cytoskeleton
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AP Biology
2005-2006
Cytoskeleton Function
u structural support maintains shape of cell provides anchorage for organelles
u motility cell locomotion cilia, flagella, etc.
u regulation organizes structures &
activities of cell
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AP Biology
2005-2006
Cytoskeleton Structure
u network of fibers extending throughout cytoplasm
u 3 main protein fibers microtubules microfilaments intermediate filaments
Its a matter of size
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AP Biology
2005-2006
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AP Biology
2005-2006
Evolutionary perspective Proteins that make up the fibers are
very similar in all living things u from bacteria to humans
tubulin (all cells) actin (eukaryote cells)
Means that they are both ancient and essential for life
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AP Biology
2005-2006
Microtubules Structure
u thickest fibers u hollow rods about 25nm
in diameter u constructed of protein,
tubulin u grow or shrink as more
tubulin molecules are added or removed
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AP Biology
2005-2006
Microtubules Function
u structural support & cell movement move chromosomes during cell division
w centrioles tracks that guide motor proteins carrying
organelles to their destination w motor proteins: myosin & dynein
motility w cilia w flagella
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AP Biology
2005-2006
Centrioles Cell division
u in animal cells, pair of centrioles organize microtubules guiding chromosomes in cell division
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AP Biology
2005-2006
Cilia & flagella Extensions of eukaryotic cytoskeleton Cilia = numerous & short (hair-like) Flagella = 1-2/cell & longer (whip-like)
u move unicellular & small multicellular organisms by propelling water past them
u cilia sweep mucus & debris from lungs u flagellum of sperm cells
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AP Biology
2005-2006
Cilia Oar-like movement
u alternating power & recovery strokes u generate force perpendicular to cilias
axis
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AP Biology
2005-2006
Flagella undulatory movement
u force generated parallel to flagellums axis
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AP Biology
2005-2006
Cilia & Flagella Structure
u remember 9+2! u 9 pairs of
microtubules around 2 single microtubules in center
u bending of cilia & flagella is driven by motor protein dynein
requires ATP
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AP Biology
2005-2006
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AP Biology
2005-2006
Microfilaments (actin filaments) Structure
u thinnest class of fibers u solid rods of protein, actin u twisted double chain of actin
subunits u about 7nm in diameter
Function u 3-D network inside cell membrane u in muscle cells, actin filaments
interact with myosin filaments to create muscle contraction
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AP Biology
2005-2006
Microfilaments (actin filaments) Dynamic process
u actin filaments constantly form & dissolve making the cytoplasm liquid or stiff during movement movement of Amoeba cytoplasmic streaming in plant cells
w speeds distribution of materials
Lets go to the video tape! (play movie here)
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AP Biology
2005-2006
Intermediate filaments Structure
u specialized for bearing tension u built from keratin proteins
same protein as hair u intermediate in size 8-12nm
Function u hold things in place inside cell u more permanent fixtures of
cytoskeleton u reinforce cell shape & fix
organelle location nucleus is held in place by a
network of intermediate filaments
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AP Biology
2005-2006
Summary Microtubules
u thickest u cell structure & cell motility u tubulin
Microfilaments u thinnest u internal movements
within cell u actin, myosin
Intermediate filaments u intermediate u more permanent fixtures u keratin
actin microtubule nuclei
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AP Biology
2005-2006
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AP Biology
2005-2006
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AP Biology
2005-2006
Cell Junctions
Where cells touch each other
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AP Biology
2005-2006
Plant cell wall Structure
u cellulose u primary cell wall u secondary cell wall u middle lamella = sticky polysaccharides
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AP Biology
2005-2006
Intercellular junctions Plant cells
u plasmodesmata channels allowing cytosol
to pass between cells
plasmodesmata
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AP Biology
2005-2006
Animal cell surface Extracellular matrix
u collagen fibers in network of glycoproteins support adhesion movement regulation
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AP Biology
2005-2006
Intercellular junctions in animals
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AP Biology
2005-2006
Intercellular junctions Animal cells
u tight junctions membranes of adjacent cells fused forming
barrier between cells forces material through cell membrane
u gap junctions communicating junctions allow cytoplasmic movement between
adjacent cells u desmosomes
anchoring junctions fasten cells together in strong sheets
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AP Biology
2005-2006
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AP Biology
2005-2006
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AP Biology
2005-2006
A cell is a living unit greater
than the sum of its parts
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AP Biology
2005-2006
And now for some Stupid Penguin Tricks.
Any Questions??