Download 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
Making New Cells
AP Biology
2013-2014
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
AP Biology
3 kinds of protein filaments
 Microtubules, Microfilaments &
Intermediate Filaments
http://www.youtube.com/watch?v=TnDeITPGQjk
Summarize in a table.
AP Biology
Cytoskeleton
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.
Intermediate Filaments: interwoven, rope-strands
built from a family of proteins
called keratins.
AP Biology
Function: Strength, maintain shape, fix organelle location.
http://www.studiodaily.com/main/searchlist/6850.html
 Intermediate
filaments
 microtubules
AP Biology
 microfilaments
Cytoskeleton
 microfilament (actin)
 microtubule (tubulin)
 nuclei
AP Biology
Cytoskeleton
Intermediate filaments
AP Biology
Subunit is heterodimer
of a and b tubulin
Microtubules
http://sites.sinauer.com/cooper5e/animatio
n1203.html
http://www.dnatube.com/video/4216/Howkinesin-walks-over-microtubules
http://vimeo.com/45238275
AP Biology
http://www.dnatube.com/video/5002/Microtubules-Video
Motors:
kinesins &
dyneins
Centrioles
http://www.youtube.com/watch?v=VGV3fv-uZYI
 Cell division

NOT IN PLANT CELLS
in animal cells, a pair of centrioles
organize microtubules

spindle fibers
Microtubules guide chromosomes in mitosis
and keep the cell from collapsing
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
AP Biology
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)
AP Biology
http://programs.northlandcollege.edu/biolo
gy/biology1111/animations/flagellum.html
Movement
Cilia & Flagella differ in their beating patterns.
“rowing”
AP Biology
“whipping”
http://programs.northlandcollege.edu/biolo
gy/biology1111/animations/flagellum.swf
Microfilaments
AP Biology
http://www.youtube.com/watch?v=Ch3izZOUjDs
Intermediate Filaments
primary role:
to provide physical strength
to cells and tissues
AP Biology
http://iknow.net/player_window.html?url=media/cytoskeleton_au
to.swf&width=360&height=159
Summary
 http://www.youtube.com/watch?v=-bDg4gMYpsI&feature=related
AP Biology
Cell Wall
 Maintains shape and size of plant cell;
prevents enlargement.
 Plays important roles in the absorption,
transport and secretion of substances.
AP Biology
Animal cells lack a cell wall,
but have cytoskeleton and…
Extracellular Matrix (ECM)
 support
 adhesion
 movement
 regulation
Major components: glycoproteins secreted by the cells;
Collagen – most abundant glycoprotein in ECM
AP Biology
Extracellular Matrix
 Connects intra- and extra-cellular environments
AP Biology
ECM
 Lots of
interactions
involved
Pathways shown for
illustration purposes
only.
AP Biology
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
http://multimedia.mcb.harvard.edu/flash/extravas
ation.swf
Inactive integrin (red, blue); talin (yellow):
when talin binds (intracellularly),
integrin becomes active & interacts extracellularly with ecm.
Start at 2:42
http://www.dnatube.com/video/551/TheInner-Life-Of-A-Cell-HQ
AP Biology
You do not need to know about integrin activation.
I’ve included it here only because you saw it in the cell video.
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
AP Biology