cytoskeleton - the bronx high school of science cell ch6...cytoskeleton function structural support...
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AP Biology
CYTOSKELETON
AP Biology
Cells gotta work to live! What jobs do cells have to do?
make proteins
proteins control every
cell function
make energy
for daily life
for growth
make more cells
growth
repair
renewal
AP Biology 2013-2014
Making New Cells
AP Biology
Cytoskeleton Function
structural support maintains shape of cell
provides anchorage for organelles
protein fibers
microfilaments, intermediate filaments, microtubules
motility cell locomotion
cilia, flagella, etc.
regulation
organizes structures
& activities of cell
3 kinds of protein filaments
AP Biology
Microtubules, Microfilaments &
Intermediate Filaments
Summarize in a table.
http://www.youtube.com/watch?v=TnDeITPGQjk
AP Biology
Cytoskeleton
Intermediate Filaments: interwoven, rope-strands
built from a family of proteins
called keratins.
Function: Strength, maintain shape, fix organelle location.
Microtubules: tubes composed of
spiraling tubulin in two-part subunits. Function: shape & support
chromosome movement (centriole, spindle fibers)
movement of organelles (serve as tracks)
movement of cellular appendages (cilia, flagella)
“highways” along which the organelles travel Microtubule roads are dynamic. Assembled at one end
while being disassembled at the other.
Microfilaments: twisted double chain of actin subunits
Function: to bear tension,
resists pulling tensions within cell
(prevents cell from collapsing)
motility (cell movement) and shape,
and simply holding the cell together.
http://www.studiodaily.com/main/searchlist/6850.html
AP Biology
microfilaments
Intermediate
filaments
microtubules
AP Biology
microfilament (actin)
microtubule (tubulin)
nuclei
Cytoskeleton
AP Biology
Cytoskeleton
Intermediate filaments
AP Biology
http://sites.sinauer.com/cooper5e/animatio
n1203.html
http://www.dnatube.com/video/4216/How-
kinesin-walks-over-microtubules
http://vimeo.com/45238275
Motors:
kinesins &
dyneins
Microtubules Subunit is heterodimer
of a and b tubulin
http://www.dnatube.com/video/5002/Microtubules-Video
AP Biology
Centrioles Cell division
in animal cells, a pair of centrioles organize microtubules
spindle fibers
Microtubules guide chromosomes in mitosis and keep the cell from collapsing
http://www.youtube.com/watch?v=VGV3fv-uZYI
NOT IN PLANT CELLS
AP Biology
Centrioles Organization and movement
of chromosomes
} motors
AP Biology
Centrosomes & Cancer Cancer cells often are aneuploid (have abnormal numbers
of chromosomes) role of centrosomes?
Chromosome movement in mitosis also involves
polymerization and depolymerization of microtubules.
Vincristine (found in the Madagascar periwinkle - a wildflower)
binds to tubulin dimers
prevents the assembly of microtubules
halts cells in metaphase of mitosis
How would you design
a chemotherapy drug?
AP Biology
Anticancer Drugs Often target microtubules
Taxol® (found in the bark of
the Pacific yew)
-prevents depolymerization of
microtubules of the spindle
fiber
stops chromosome
movement
prevents the completion of
mitosis.
AP Biology
Centriole Structure 9 sets of triplets,
no central doublet
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Basal Bodies modified centrioles that give rise to
cilia and flagella
AP Biology
Cilia & Flagella – composed of microtubules “9 + 2” tubulin pattern
(9 outer doublets, 2 microtubules in center)
http://programs.northlandcollege.edu/biolo
gy/biology1111/animations/flagellum.html
AP Biology
Movement Cilia & Flagella differ in their beating patterns.
http://programs.northlandcollege.edu/biolo
gy/biology1111/animations/flagellum.swf
“rowing” “whipping”
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Microfilaments
http://www.youtube.com/watch?v=Ch3izZOUjDs
AP Biology
Intermediate Filaments
primary role:
to provide physical strength
to cells and tissues
http://iknow.net/player_window.html?url=media/cytoskeleton_au
to.swf&width=360&height=159
AP Biology
http://www.youtube.com/watch?v=-bDg4gMYpsI&feature=related
Summary
AP Biology
Cell Wall Maintains shape and size of plant cell;
prevents enlargement.
Animal cells lack a cell wall,
but have cytoskeleton and…
Plays important roles in the absorption,
transport and secretion of substances.
AP Biology
Extracellular Matrix (ECM)
adhesion
movement
regulation
support
Major components: glycoproteins secreted by the cells;
Collagen – most abundant glycoprotein in ECM
AP Biology
Extracellular Matrix Connects intra- and extra-cellular environments
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ECM
Lots of
interactions
involved
Pathways shown for
illustration purposes
only.
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ECM
Many processes
You should know that ECM
involves a set of proteins
called integrins, connects
intra- and extracellular
environments and is
essential to normal cell
function.
AP Biology
Integrin activation Inactive integrin (red, blue); talin (yellow):
when talin binds (intracellularly),
integrin becomes active & interacts extracellularly with ecm.
http://multimedia.mcb.harvard.edu/flash/extravas
ation.swf
http://www.dnatube.com/video/551/The-
Inner-Life-Of-A-Cell-HQ
Start at 2:42
You do not need to know about integrin activation.
I’ve included it here only because you saw it in the cell video.
AP Biology
Integrins
Again, proteins
are involved in
interactions.
(You do not need
to know the
details in this
slide.)
AP Biology
AP Biology
The Cell http://www.dnatube.com/video/551/The-Inner-Life-Of-A-Cell-HQ
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