Microtubules

Definition

Microtubules are cylindrical structures made of tubulin protein that play a critical role in maintaining cell shape, enabling cellular transport, and facilitating cell division. They are one of the three main components of the cytoskeleton, providing structural support and aiding in various cellular functions, such as chromosome movement during mitosis and serving as tracks for motor proteins.

5 Must Know Facts For Your Next Test

1. Microtubules are composed of alpha and beta tubulin dimers, which polymerize to form long, hollow tubes.
2. They have a dynamic nature, meaning they can rapidly grow and shrink by adding or removing tubulin subunits, a process known as dynamic instability.
3. Microtubules assist in the separation of chromosomes during cell division by forming the mitotic spindle.
4. They also serve as tracks for motor proteins, such as kinesin and dynein, which transport organelles and vesicles throughout the cell.
5. Disruption of microtubule function can lead to serious consequences for the cell, including issues with cell division and transport processes.

Review Questions

• How do microtubules contribute to the structure and function of the cytoskeleton?
  • Microtubules are one of the key components of the cytoskeleton, providing structural support and shape to the cell. They work alongside intermediate filaments and actin filaments to maintain cellular integrity. Additionally, microtubules enable dynamic changes in cell shape and play a role in intracellular transport by serving as tracks for motor proteins.
• Discuss the role of microtubules during mitosis and how they ensure accurate chromosome segregation.
  • During mitosis, microtubules form the mitotic spindle, which is essential for the proper segregation of chromosomes. The spindle fibers attach to kinetochores on chromosomes, pulling them apart towards opposite poles of the cell. This process ensures that each daughter cell receives an identical set of chromosomes, preventing genetic abnormalities.
• Evaluate the implications of microtubule dysfunction in human diseases, particularly cancer.
  • Microtubule dysfunction can have severe implications in human health, particularly in diseases like cancer. Abnormalities in microtubule dynamics can lead to errors in chromosome segregation during cell division, contributing to aneuploidy—a hallmark of many cancers. Additionally, drugs that target microtubules, such as taxanes and vinca alkaloids, are commonly used in cancer treatment to disrupt mitosis and inhibit tumor growth.

Related terms

Cytoskeleton: The network of protein filaments and tubules that gives cells their shape and allows for movement and transport within the cell.

Motor Proteins: Proteins that use energy to produce movement along microtubules and actin filaments, transporting cellular cargo or facilitating muscle contraction.

Centrioles: Cylindrical structures made of microtubules that play a key role in cell division by helping organize the mitotic spindle.