CYTOSKELETON AND EXTRACELLULAR MATRIXBlock 5 Erik Kessler, Michael O’Brien, Bryan Richman

• Meshwork of fine fibers within the cell

• Made up of three types of fibers

– Microfilaments, Intermediate Filaments, and Microtubules

• Gives the cell some structural support

• Plays a role in cell movement

– Movement of organelles, and cell itself

– Needed for muscle contraction

• Regulates cellular activity

CYTOSKELETON

Structure:

Function:

More in textbook pg.64

• Solid rod made mostly of the globular protein actin

• Double twisted chain that is 5-9 nm in diameter

• Changes shape by moving subunits from the end to the front

– This can change cell shape and make it move ex.

Amoeba

• Can interact with myosin to contract muscles

• Allows a dividing cell (cytokinesis) to pinch off

into two cells

MICROFILAMENTS

Structure:

Function:

More in textbook pg.64

Globular proteins are hydrophilic

• Rope-like structure

• Made of fibrous protein

• 8-11 nm in diameter

• Made of subunits

– monomer - rod connecting amino head to carboxyl tail

– dimer - two monomers combine

– tetramer - two dimers combined

– tetramers combine into sheets which role up into its rope

shape

INTERMEDIATE FILAMENTS

Structure:

More in textbook pg.64

Fibrous proteins are hydrophobic

• Keep organelles in place and holds the cell structure

– ex. Hold nucleus in place

• Can assemble and disassemble through phosphorylation

with serine

• Can bind with different proteins to improve stability or

create attachment sites for protein assemblies

– ex. actin filaments (microfilaments), microtubules

• Help to attach chromosomes to nuclear membrane

INTERMEDIATE FILAMENTS

Function:

More in textbook pg.64

• Made of globular proteins

• 20-25 nm in diameter

• Act as track for organelle movement through cytoplasm

– ex. lysosomes move along microtubules to reach vacuole,

also support and move cilia and flagella

• Guide chromosomes when cells divide

• Move by adding tubulin to one end and losing them on the

other

MICROTUBULES

Structure:

Function:

More in textbook pg.64And watch the cilia and flagella PowerPoint for more on their function

• Sticky layer of glycoproteins

• Made of: collagen and elastin (structural proteins), fibrillin and

laminin (specialized proteins)

• Holds animal cells together in tissues

• Protects and supports cells

• Regulates cell behavior

• Gives strength, protection, and support to soft parts of the body

(cartilage, etc.)

EXTRACELLULAR MATRIX

Structure:

Function:

More in textbook pg.66

• Adjacent cells in animal tissues are connected by cell junctions

• Regulates what comes into the cell

• Tight Junction: Binds cells together and forms a leak proof sheet

– Prevents passage of molecules through the space between cells

• Anchoring Junction: Attach cells to each other while still allowing material to

pass in the area between the cells

• Communicating Junction: Channels allowing water, small molecules, and ions

to flow between adjacent cells- cells can communicate

with electrical/ chemical signals

CELL JUNCTIONS

Types:

Function:

More in textbook pg.66

Mitchell, and Reece. "Chapter 4: A Tour of the Cell." Biology: Concepts and Connections. By Campell. 3rd ed. San Francisco: Benjamin/Cummings, 2000. 64-66. Print.

Digital image. Http://academic.brooklyn.cuny.edu. Web. 26 Nov. 2010. <http://academic.brooklyn.cuny.edu/biology/bio4fv/page/actin1063.JPG>.Digital image. Http://academic.brooklyn.cuny.edu. Web. 26 Nov. 2010. <http://academic.brooklyn.cuny.edu/biology/bio4fv/page/intermiediate-fil1063.JPG>.Digital image. Http://www.bscb.org. Web. 26 Nov. 2010. <http://www.bscb.org/softcell/images/mp_tripple.gif>.Digital image. Web. 26 Nov. 2010. <http://219.221.200.61/ywwy/zbsw(E)/pic/ech4-1.jpg>."Cytoskeleton." ISCID - International Society for Complexity Information and Design. Web. 23 Nov. 2010. <http://www.iscid.org/encyclopedia/Cytoskeleton>. "Cytoskeleton Tutorial." The Biology Project. 2004. Web. 23 Nov. 2010. <http://www.biology.arizona.edu/cell_bio/tutorials/cytoskeleton/page1.html>."Intermediate Filaments." Cell Biology and Cytochemistry. Web. 23 Nov. 2010. <http://www.cytochemistry.net/cell-biology/intermediate_filaments.htm>. "Microtubules." Cell Biology and Cytochemistry. Web. 27 Nov. 2010. <http://www.cytochemistry.net/cell-biology/microtub.htm>. "Microtubules." Rensselaer Polytechnic Institute (RPI) :: Architecture, Business, Engineering, IT, Humanities, Science. Web. 23 Nov. 2010. <http://rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/microtub.htm>. "Molecular Expressions Cell Biology: Intermediate Filaments." Molecular Expressions: Images from the Microscope. Web. 27 Nov. 2010. <http://micro.magnet.fsu.edu/cells/intermediatefilaments/intermediatefilaments.html>"Cytoskeleton Tutorial." The Biology Project. Web. 30 Nov. 2010. <http://www.biology.arizona.edu/cell_bio/tutorials/cytoskeleton/page1.html>.<http://rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/microtub.htm>. "Molecular Expressions Cell Biology: Intermediate Filaments." Molecular Expressions: Images from the Microscope. Web. 27 Nov. 2010. <http://micro.magnet.fsu.edu/cells/intermediatefilaments/intermediatefilaments.html>."The Extracellular Matrix." 12 Apr. 2009. Web. 1 Dec. 2010. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ECM.html>.

 "Microtubules." Cell Biology and Cytochemistry. Web. 27 Nov. 2010. <http://www.cytochemistry.net/cell-biology/microtub.htm>. "Microtubules." Rensselaer Polytechnic Institute (RPI) :: Architecture, Business, Engineering, IT, Humanities, Science. Web. 23 Nov. 2010. 

"Junctions Between Cells." 10 Oct. 2010. Web. 1 Dec. 2010. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/J/Junctions.html>.

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