Centromere and Kinetochore are the two primary structures located in the approximate middle of chromosomes. At the time of cell division, they are extremely important for sister chromatid segregation. The primary difference between Centromere and Kinetochore is that the centromere is the region of the chromosome that holds two sister chromatids, whereas the kinetochore is the disc-shaped protein complex of the chromosome.
Difference Between Centromere and Kinetochore
The below table highlights the primary differences between Centromere and Kinetochore:
Features | Centromere | Kinetochore |
|---|---|---|
Composition | A chromosomal DNA segment that is constrained. | A protein complex that is put together on the centromere of chromosomes. |
Observation | Visible with a light microscope. | Visible with an electron microscope. |
Structure | Comprised of centric heterochromatin. | Comprised of specialized histone types like CENP-A. |
Position | Consists of four positions: telocentric, acrocentric, submetacentric, and metacentric. | Consists of two layers, the inner and outer kinetochores. |
Number | It may be holocentric or monocentric. | There is one kinetochore complex per centromere. |
Binding with Microtubules | Avoids interacting with microtubules. | About 20 anchoring spots can be found on the outer kinetochore. |
Primary Function | Holding sister chromatids together. | Creating a location for the attachment of microtubules. |
Corona | Doesn't possess a corona. | Usually have a corona. |
Layers | Have no layers. | Usually has two layers. |
What is Centromere?
The centromere is the region of a duplicated chromosome that connects the two sister chromatids. The kind of heterochromatin located in the centromere of a chromosome is known as centric heterochromatin. Pericentric heterochromatin surrounds the centric heterochromatin in both directions. The two sister chromatids that collectively make the replicated chromosome are connected by cohesin protein complexes.
The kinetochore, a protein complex assembled on the centromere of the chromosome, is responsible for binding microtubules to the centromere of the chromosome. On chromosomes, there are two different kinds of centromeres: point centromeres and regional centrosomes. To generate centromeres, point centromeres interact with particular proteins. Regional centromeres can also arise on other DNA sequences; however, the centromere prefers to form on a distinct DNA sequence.
What is Kinetochore?
In the anaphase of cell division, chromosomal centromeres develop a protein complex called a kinetochore, to which spindle microtubules are attached and which pull sister chromatids or chromosomes apart. In contrast to monocentric creatures, which have a single place where kinetochores assemble, holocentric animals show kinetochores assembled across the entire chromosome. Kinetochores help spindle microtubules connect to the chromosome and hold two sister chromatids together along with cohesin protein complexes.
Structure of Kinetochore
The inner and outer kinetochore are the two distinct areas of a kinetochore. The two sister chromatids are kept together by the inner kinetochore's close association with the centromere region. It contains nucleosomes that lack histone H3 and instead are composed of specialized histones called CENP-A. The spindle microtubules and the outer kinetochore engage in interaction. Following the breakdown of the nuclear envelope, it is assembled on the surface of the chromosome. There are roughly 20 locations for kinetochore microtubule anchoring in the outer kinetochore.
Core Difference between Centromere and Kinetochore
The following are some major differences between Centromere and Kinetochore:
- A kinetochore is a protein complex that binds to the centromere, which is the primary region of condensed chromosomes.
- Under a light microscope, the centromere is clearly visible, whereas an electron microscope makes the kinetochore visible.
- Kinetochore is one kinetochore complex, whereas centromere can be either monocentric or holocentric.
- Centromere is made up of centric heterochromatin, whereas the kinetochore is constructed from certain histone subtypes.