![]() ![]() ![]() ![]() The intermediate filaments are the most diverse group of cytoskeletal elements. Figure 4.22 shows how intermediate filaments create a supportive scaffolding inside the cell. They bear tension, thus maintaining the shape of the cell, and anchor the nucleus and other organelles in place. Intermediate filaments have no role in cell movement. Although the molecular structures of cytoskeleton proteins are similar between two types of cells, the actual amino acid sequences of these proteins show very low levels of homology between the cytoskeleton proteins in prokaryotes and eukaryotes.įigure 4.24 Intermediate filaments consist of several intertwined strands of fibrous proteins. The line itself can grow and shrink by adding or taking away students in the line, respectively.īoth prokaryotic and eukaryotic cells possess cytoskeletons involved in cell division and shape maintenance. Then, on by one, ask students from the pool to exchange places with a student standing in the line. Another way to demonstrate this is to have a few students stand in a line and then have a “pool” of students stand nearby. Stress the concept of “dynamic equilibrium.” A vivid animation may illustrate the point better. The subunits of the cytoskeleton assemble and disassemble constantly, which is hard to imagine. A Learning Objective merges required content with one or more of the seven Science Practices.ĭescribe the cytoskeleton both as a “skeleton” because it provides the cell with shape and as “muscles” because it allows cells to move. The Learning Objectives listed in the Curriculum Framework provide a transparent foundation for the AP ® Biology course, an inquiry-based laboratory experience, instructional activities, and AP ® exam questions. The information presented and the examples highlighted in the section support concepts and Learning Objectives outlined in Big Idea 1 of the AP Biology Curriculum Framework, as shown in the table below. These protein elements are also integral to the movement of centrioles, flagella, and cilia. The cytoskeleton serves a variety of purposes: provides rigidity and shape to the cell, facilitates cellular movement, anchors the nucleus and other organelles in place, moves vesicles through the cell, and pulls replicated chromosomes to the poles of a dividing cell. How do the various components of the cytoskeleton perform their functions?Īll cells, from simple bacteria to complex eukaryotes, possess a cytoskeleton composed of different types of protein elements, including microfilaments, intermediate filaments, and microtubules.In this section, you will explore the following questions: ![]()
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