Introduction to the cytoskeleton Flashcards
What are some key things cells can do?
Cells can produce RNA, proteins, and energy, move around, communicate with other cells, and interact with their surroundings through cytoskeletal and adhesion mechanisms.
How do cells generate force and sense it?
Cells use their cytoskeleton to generate and sense mechanical force at the membrane, which is essential for movement, adhesion, and altering gene transcription and cell behavior.
How is force involved in cell division?
Force is generated by pulling spindles apart during mitosis, and cell membranes must split to complete cell division.
How does the cytoskeleton contribute to intracellular transport?
The cytoskeleton, especially microtubules, acts like highways that transport molecules, such as proteins, to different parts of the cell, including the cell surface.
What is an example of force-based cell movement?
Neutrophils chase bacteria by pushing their membrane forward using actin-driven force.
How is cell shape influenced by the cytoskeleton?
Different shapes—like elongated muscle cells or round red blood cells—are formed through force exerted by the cytoskeleton at the membrane.
What is the main component of actin filaments?
G-actin (globular actin) polymerizes to form F-actin (filamentous actin), the primary structural unit.
What roles does the cytoskeleton play?
It provides structure, enables movement, supports intracellular transport (via microtubules), and drives shape change (via actin filaments).
Why is force needed for changing cell size?
Mechanical force applied via the cytoskeleton allows cells to expand or contract as needed.
What does profilin do in actin dynamics?
Profilin regulates actin polymerization by preventing spontaneous F-actin nucleation and promoting controlled filament formation.
What are the roles of actin-binding proteins?
They stabilize actin filaments, nucleate new ones, and organize them into functional networks for movement and shape control.
What is treadmilling in actin filaments?
It’s the process where ATP-actin adds to the + end of filaments while ADP-actin is removed from the - end, maintaining dynamic filament length.
How are filopodia formed?
Linear actin filaments nucleated by formins like VASP and bundled by fascin form thin, finger-like protrusions for sensing and movement
What are lamellipodia and what structures support them?
Lamellipodia are broad, sheet-like actin structures at the cell front, formed by branched actin arrays supported by the lamellum.
What does the Arp2/3 complex do?
It nucleates branched actin filaments, important for generating lamellipodia during cell migration.
How does tropomyosin affect actin branching?
Tropomyosin promotes linear filament formation by preventing Arp2/3 and cofilin from binding, thus blocking actin branching.
What structure is formed by actin-myosin bundles?
They form contractile structures like stress fibers that help the cell generate internal tension and contractility.
