Difference Between Kinetochore and Nonkinetochore Microtubules

The key difference between kinetochore and nonkinetochore microtubules is that kinetochore microtubules are directly attached to kinetochore of chromosomes and move them towards the poles during mitosis while nonkinetochore microtubules do not connect with the kinetochore of chromosomes.

Kinetochore is a disk-shaped protein structure assembled on the centromeric region of DNA. Kinetochore provides the major attachment point for the spindle microtubules during mitotic or meiotic division to pull the chromosomes apart. Therefore, kinetochore ensures the proper distribution of DNA to daughter cells. There are two types of microtubules as kinetochore microtubules and nonkinetochore microtubules. Kinetochore microtubules are attached to chromosomes and move them towards poles. Nonkinetochore microtubules are mitotic spindles that do not interact with kinetochore of the chromosomes. They participate in elongating the cell during anaphase.

CONTENTS

1. Overview and Key Difference
2. What are Kinetochore Microtubules
3. What are Nonkinetochore Microtubules
4. Similarities Between Kinetochore and Nonkinetochore Microtubules
5. Side by Side Comparison – Kinetochore vs Nonkinetochore Microtubules in Tabular Form
6. Summary

What are Kinetochore Microtubules?

Microtubules are components of the cytoskeleton. They are involved in mitosis, cell motility, intracellular transport and maintenance of the cell shape. Kinetochore microtubules are a type of microtubules that connect with the kinetochore of chromosomes during mitosis. They are capable of invading nuclear space. During segregation of chromosomes in mitosis, chromosomes move towards the poles due to the interaction with kinetochore microtubules. Therefore, kinetochore microtubules are responsible for moving chromosomes to the opposite ends of the cell during mitosis.

What are Nonkinetochore Microtubules?

Nonkinetochore microtubules are mitotic spindles that do not interact with kinetochore of chromosomes. They are also known as polar microtubules. They are not connected to chromosomes during the mitosis. These microtubules find and interact with the corresponding nonkinetochore microtubules from the opposite centrosomes to form the mitotic spindles. Nonkinetochore microtubules are responsible for elongating the cell during anaphase.

Moreover, nonkinetochore microtubules are charged. They overlap and push against each other, moving centrosomes apart. Hence, these microtubules are responsible for pushing centrosomes apart.

What are the Similarities Between Kinetochore and Nonkinetochore Microtubules?

• They are two types of microtubules of cells.
• Both kinetochore microtubules and nonkinetochore microtubules are essential for a successful cell division.

What is the Difference Between Kinetochore and Nonkinetochore Microtubules?

Kinetochore microtubules are microtubules that are connected to the kinetochores of chromosomes during mitosis. In contrast, nonkinetochore microtubules are microtubules that are not connected to chromosomes during mitosis. Thus, this is the key difference between kinetochore and nonkinetochore microtubules.

Moreover, kinetochore microtubules are responsible for moving chromosomes towards poles in order to distribute chromosomes for daughter cells. However, nonkinetochore microtubules are responsible for pushing centrosomes apart and cellular elongation. Also, another difference between kinetochore and nonkinetochore microtubules is their role in cell elongation; nonkinetochore microtubules are responsible for cellular elongation while kinetochore microtubules are not.

The below infographic summarizes the differences between kinetochore and nonkinetochore microtubules in tabular form.

Summary – Kinetochore vs Nonkinetochore Microtubules

Kinetochore microtubules and nonkinetochore microtubules are two types of microtubules in a cell. Kinetochore microtubules directly interact and attach with kinetochores of chromosomes. They are responsible for correct segregation of chromosomes into daughter cells. Nonkinetochore microtubules are not attached to kinetochores. They interact with chromosome arms and other nonkinetochore microtubules from the corresponding centrosomes. Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell. So, this is the key difference between kinetochore and nonkinetochore microtubules.

Reference:

1. “Prometaphase.” Wikipedia, Wikimedia Foundation, 6 May 2020, Available here.

Image Courtesy:

1. “Spindle apparatus” By Lordjuppiter – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Prometaphase” By Kelvinsong – Own work (CC BY 3.0) via Commons Wikimedia