bio 178 lecture 9 cell structure copyright: e.g. platzer
Post on 19-Dec-2015
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TRANSCRIPT
Reading
• Chapter 5
Quiz Material
• Questions on P 104
• Chapter 5 Quiz on Text Website (www.mhhe.com/raven7)
The Cytoskeleton
Intermediate Filaments
Microtubules Actin Filaments
http://www.tmd.ac.jp/artsci/biol/textbook/cellmove.htm
MicrotubulesSize~ 25 nm diam
Composition
• Hollow tubes - 13 protofilaments.
• Each subunit - tubulin heterodimer of - and - tubulin monomers.
http://www.tmd.ac.jp/artsci/biol/textbook/cellmove.htm
Microtubules in Fish Fibroblast Cell
http://cellix.imolbio.oeaw.ac.at/Videotour/video_tour_12.html
Cy tubulin growing into adhesion sites
Intermediate FilamentsSize8-10 nm
CompositionRopes of a heterogeneous mix of fibrous proteins (eg. vimentin, keratin)
Centrosome• The primary microtubule organizing center of animals and acts as the spindle pole during mitosis.
• Usually contains a pair of centrioles.
• Located near nucleus.
Structure• Not membrane-bound.
• 9 triplets of microtubules.
“The centrosome is the main microtubule organizing center (MTOC) of the cell. It is composed of two orthogonally arranged centrioles surrounded by an amorphous mass of pericentriolar material (PCM)”.
http://en.wikipedia.org/wiki/Centrosome
The Centriole
The Centriole (cntd)
KingdomsAnimals and some protists
Functions
• Microtubule assembly
• Anchor of cilia and flagella (basal bodies)
http://www-cteu.u-bourgogne.fr/cav/dicobio/fiches/centriole.html
Molecular MotorsDescription• Proteins that transport organelles, chromosomes, and vesicles using the cytoskeleton as a “highway”.
• Use ATP for energy.
Motor Types• Differ in the type of filament they bind to, cargo they carry, and directionality.
• Examples - Dynein, kinesin, myosin.