Txbk: Ch 6.6 Flashcards
(15 cards)
What is the cytoskeleton, and where is it located?
The cytoskeleton is a network of fibers extending throughout the cytoplasm of eukaryotic cells, responsible for organizing cell structures and activities.
What are the three main types of fibers that make up the cytoskeleton?
The three main types are microtubules, microfilaments (also called actin filaments), and intermediate filaments.
What are the primary roles of the cytoskeleton in a cell?
The cytoskeleton provides mechanical support, maintains cell shape, facilitates cell motility, organizes organelles, and assists in cellular transport and signaling.
How does the cytoskeleton contribute to cell motility?
Cell motility involves the interaction of cytoskeleton elements with motor proteins to facilitate movement of the cell or organelles within the cell.
What is the structure and function of microtubules?
Microtubules are hollow rods made of tubulin dimers, providing cell shape and support, acting as tracks for organelle movement, and playing a key role in cell division.
What is the “plus end” of a microtubule, and why is it significant?
The “plus end” is the more dynamic end of a microtubule where tubulin dimers add and release more rapidly, allowing growth and reorganization within the cell.
Where do microtubules grow out from in animal cells?
Microtubules grow out from the centrosome, a microtubule-organizing center located near the nucleus, containing a pair of centrioles.
What is the role of cilia and flagella in cells?
Cilia and flagella are microtubule-based structures used for cell movement or moving fluids across the cell surface. Cilia beat in coordinated waves, while flagella move with an undulating motion.
What are microfilaments, and what is their primary structural role?
Microfilaments are thin rods of actin that bear tension and contribute to the cell’s shape, support, and motility, particularly in muscle contraction and cell crawling.
How do microfilaments contribute to muscle contraction?
Microfilaments interact with myosin motor proteins, allowing actin filaments to slide and shorten, which results in muscle cell contraction.
What role do microfilaments play in cell division?
During cell division, a contractile ring of microfilaments forms a cleavage furrow, which pinches the cell into two daughter cells.
What is cytoplasmic streaming, and which cytoskeletal component facilitates it?
Cytoplasmic streaming is the circular flow of cytoplasm within large plant cells, facilitated by microfilaments to distribute materials efficiently.
What are intermediate filaments, and what are their key characteristics?
Intermediate filaments are durable structures that bear tension and provide structural integrity. They vary in protein composition and remain more permanent than other cytoskeleton components.
How do intermediate filaments support cell structure?
Intermediate filaments reinforce cell shape, fix organelle positions, and are especially durable, remaining intact even after cell death, such as in the outer layer of skin cells.
How do intermediate filaments support the nucleus?
Intermediate filaments form a cage around the nucleus and contribute to the nuclear lamina, supporting nuclear structure and positioning within the cell.
