BIO 101 1st Edition Outline of Last Lecture I Main Kinds of Cells a Prokaryotic b Eukaryotic II Cell Size III Eukaryotic Cell Components IV Endomembrane System V Other Organelles Lecture 10 Outline of Current Lecture I Cytoskeleton a Microtubules b Microfilaments c Intermediate filaments II The Cell Surface a Cell Walls b Gylcocalyx c Intercellular Junctions Chapter 6 cont Cytoskeleton network of fibers throughout cytoplasm provides internal support 3 types of fibers 1 Microtubules hollow rods of protein tubulin thickest of 3 fibers approx 25nm Functions a Pathway for organelle movement b Make up centrioles involved in cell division c Cell motility microtubules make up cilia and flagella 2 Microfilaments thin fibers approx 7nm of intertwined helix of protein actin Functions a Muscle contraction b Support c Cytoplasmic streaming in plants d Amoeboid movement 3 Intermediate filaments intermediate thickness diverse composition Functions a Reinforce cell shape b Fix organelle position c May be framework of cytoskeleton more permanent that other 2 fibers The Cell Surface most cells produce a layer of material external to plasma membrane A Cell Walls plants and algae Strong cellulose fibers in matrix of other polysacchardies and proteins BIO 101 1st Edition Function to protect plant cell maintain shape prevent excess H2O uptake Has membrane linked channels which connect cytoplasm of neighboring cells Diagram B Gylcocalyx fuzzy coat outside plasma membrane of animal cells sticky oligosaccharides Strengthen cell surface Helps glue cells together Serves as ID in cell cell recognition C Intercellular junctions in plants plasmodesmata In animals 1 Tight junctions blocks space between cells water proofing 2 Desmosomes rivet cells together but still allows substances to move in intercellular space 3 Gap Junctions connections between cells allows intercellular transport of small molecules similar to plasmodesmata in plants
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