BIO 101 1st EditionLecture 10Outline of Last LectureI. Main Kinds of Cellsa. Prokaryoticb. EukaryoticII. Cell SizeIII. Eukaryotic Cell ComponentsIV. Endomembrane SystemV. Other OrganellesOutline of Current LectureI. Cytoskeletona. Microtubulesb. Microfilamentsc. Intermediate filamentsII. The Cell Surfacea. Cell Wallsb. Gylcocalyxc. Intercellular JunctionsChapter 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 movementb. Make up centrioles (involved in cell division)c. Cell motility- microtubules make up cilia and flagella2. Microfilaments- thin fibers (approx. 7nm) of intertwined helix of protein (actin). Functions:a. Muscle contractionb. Supportc. Cytoplasmic streaming in plantsd. Amoeboid movement3. Intermediate filaments- intermediate thickness, diverse composition. Functions:a. Reinforce cell shapeb. Fix organelle positionc. May be framework of cytoskeleton, more permanent that other 2 fibersThe Cell Surface- most cells produce a layer of material external to plasma membraneA. Cell Walls- plants and algae- Strong cellulose fibers in matrix of other polysacchardies and proteinsBIO 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 recognitionC. Intercellular junctions- in plants: plasmodesmata. In animals:1. Tight junctions: blocks space between cells= water proofing2. Desmosomes: rivet cells together but still allows substances to move in intercellular space3. Gap Junctions: connections between cells- allows intercellular transport of small molecules, similar to plasmodesmata in
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