CYTOSKELETON AND EXTRACELLULAR MATRIX Block 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 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.64 And 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, Print. Digital image. Web. 26 Nov Digital image. Web. 26 Nov Digital image. Web. 26 Nov "Cytoskeleton." ISCID - International Society for Complexity Information and Design. Web. 23 Nov "Cytoskeleton Tutorial." The Biology Project Web. 23 Nov "Intermediate Filaments." Cell Biology and Cytochemistry. Web. 23 Nov "Microtubules." Cell Biology and Cytochemistry. Web. 27 Nov "Microtubules." Rensselaer Polytechnic Institute (RPI) :: Architecture, Business, Engineering, IT, Humanities, Science. Web. 23 Nov "Molecular Expressions Cell Biology: Intermediate Filaments." Molecular Expressions: Images from the Microscope. Web. 27 Nov "Cytoskeleton Tutorial." The Biology Project. Web. 30 Nov "Molecular Expressions Cell Biology: Intermediate Filaments." Molecular Expressions: Images from the Microscope. Web. 27 Nov "The Extracellular Matrix." 12 Apr Web. 1 Dec "Microtubules." Cell Biology and Cytochemistry. Web. 27 Nov "Microtubules." Rensselaer Polytechnic Institute (RPI) :: Architecture, Business, Engineering, IT, Humanities, Science. Web. 23 Nov "Junctions Between Cells." 10 Oct Web. 1 Dec SOURCES