A cellular structure, identical to a centriole, that anchors the microtubular assembly of cilia and flagella. Built from globular protein monomers, G actin, which are linked into long chains. Two actin chains are wound into a helix . Along the length of a muscle cell, parallel actin microfilaments are interdigitated with thicker filaments made of the protein myosin, a motor molecule 3. Cell Surfaces and Junctions A. Plant cells are encased by cell walls 1.
Chemical composition varies from cell to cell and species to species.
Basic design includes strong cellulose fibers embedded in a matrix of other polysaccharides and proteins. Meshwork of macromolecules outside the plasma membrane of animal cells. Intercellular junctions that hold cells together tightly enough to block transport of substances through the intercellular space. Specialized membrane proteins in adjacent cells bond directly to each other allowing no space between membranes. Usually occur as belts all the way around each cell, that block intercellular transport.