What does dynamic instability refer to in microtubules?

What does dynamic instability refer to in microtubules?

• A. Cytoskeletal filaments grow from the minus ends
• B. Tubulin dimers move from the plus end to the minus end
• C. Microtubules shrink rapidly from the plus end upon GTP hydrolysis
• D. Actin filaments shrink rapidly from the plus end upon ATP hydrolysis

Answer: (C)

Dynamic instability in microtubules refers to the phenomenon where they undergo rapid cycles of growth and shrinkage, primarily at their plus ends. When tubulin dimers, which are the building blocks of microtubules, bind to GTP, they are added to the growing end, leading to polymerization. However, once GTP is hydrolyzed to GDP, the stability of the microtubule decreases, particularly leading to a situation where the microtubule can rapidly depolymerize or shrink from the plus end. This process is crucial for many cellular functions, including cell division and intracellular transport, as it allows microtubules to quickly adapt to the changing needs of the cell. The other options describe processes that are either characteristic of different cytoskeletal components or do not accurately capture the dynamic behavior of microtubules. For example, while actin filaments do exhibit dynamic behavior, the process described in the last option pertains specifically to actin, not microtubules. Similarly, growing from the minus end and transferring tubulin dimers are not accurate descriptors of the rapid instability associated with microtubules. Thus, understanding that dynamic instability is centered around the rapid growth and shrinkage from the

Dynamic instability in microtubules refers to the phenomenon where they undergo rapid cycles of growth and shrinkage, primarily at their plus ends. When tubulin dimers, which are the building blocks of microtubules, bind to GTP, they are added to the growing end, leading to polymerization. However, once GTP is hydrolyzed to GDP, the stability of the microtubule decreases, particularly leading to a situation where the microtubule can rapidly depolymerize or shrink from the plus end. This process is crucial for many cellular functions, including cell division and intracellular transport, as it allows microtubules to quickly adapt to the changing needs of the cell.

The other options describe processes that are either characteristic of different cytoskeletal components or do not accurately capture the dynamic behavior of microtubules. For example, while actin filaments do exhibit dynamic behavior, the process described in the last option pertains specifically to actin, not microtubules. Similarly, growing from the minus end and transferring tubulin dimers are not accurate descriptors of the rapid instability associated with microtubules. Thus, understanding that dynamic instability is centered around the rapid growth and shrinkage from the