Title: The Cytoskeleton
1The Cytoskeleton
- Protein filaments in the cytoplasm of eukaryotic
cells that - provide structural support for cell shape
- generate force for the movement of
chromosomes, organelles, and whole cells
2Coomassie blue stain of fixed epithelial cell
3Electron Micrograph of a Detergent-Extracted
Platelet
4Microfilaments are double stranded polymers of
actin
Microtubes are hollow cylinders of the protein
tubulin
Intermediate filaments are very heterogeneous
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6Keratin intermediate filaments and desmosomes
form cell sheets
7Electron micrographs of two types of intermediate
filaments in cells of the nervous system. (A)
neurofilaments in a nerve cell axon, showing the
extensive protein cross-bridges to provide great
tensile strength in this long cell process. (B)
glial filaments without cross-bridges. (C)
cross-section of an axon showing the regular
side-to-side spacing of the neurofilaments, which
greatly outnumber microtubules.
8Recessive Epidermolysis bulosa
9The nuclear lamina is made of lamin
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11Indirect immunofluorescence
A bovine pulmonary artery endothelial cell
labeled with antibovine tubulin mouse monoclonal
antibody in combination with goat antimouse IgG
antibody) to stain microtubules.
12The CENTROSOME is an MTOC (microtubule organizing
center)
13axoneme
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15Build A Microtubule
http//nessie.bch.ed.ac.uk/PAUL/MT/
16The Forth Railway Bridge across the Firth of
Forth in Scotland.
17Dynamic instability of microtubules
18http//www.bio.davidson.edu/misc/movies/tread3.MOV
19Selective stabilization of dynamic microtubules
by capping proteins can polarize a cell
20- Motor molecule families
- the dyneins move along microtubules
- the kinesins move along microtubules
- the myosins move along microfilaments
21kinesin moves toward plus end dynein moves
toward minus end
22cytoplasmic dynein and kinesin
http//www.kcl.ac.uk/depsta/biomedical/randall/ima
ges/squid.mov
23kinesin dynein
Membrane vesicle attached to MT
24Organelle placement
ER
Golgi
PLUS
MINUS
MT
MT
http//www.bio.unc.edu/faculty/salmon/lab/cler2b.m
ov
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26Microtubules control chromosomal movement during
mitosis
http//www.bio.umass.edu/biology/wadsworth/movies/
prometaphase/reeling1.html
27This Sprite is named Twink
CILIA AND FLAGELLA
28Ciliated epithelium of human trachea
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30Flagellum on sperm Flagella on Chlamydomonas
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34Demonstration of microtubule sliding in a beating
sperm flagellum http//www.cco.caltech.edu/broka
wc/Demo1/BeadExpt.html
35Dynein deficiencies in humans lead to chroninc
bronchitis and sterility
36F-actin filaments from 3T3 cells stained with
phalloidin
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38Cytochalasin produces binucleate cells
EM lab
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40Monomeric G (globular) actin
G to F polymerization Blocked by cytochalasin
41G-actin (globular) F-actin (filamentous)
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43Integrin clutch initiates forward movement
44Actin filament bundles terminate at contact
points with the glass slide on which cells are
crawling
45Muscle thin filaments
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