Difference Between Centromere and Kinetochore

Main Difference

The main difference between centromeres and kinetochore is that centromere is the section of a chromosome to which the microtubules of the spindle assign, through kinetochore, in cell division. Whereas kinetochore is a complex of proteins link with the centromere of a chromosome in a cell division to which the microtubules of the spindle attach.

Centromere vs. Kinetochore

The centromere is the region where the two sister chromatids are held together after the replication of chromosome whereas kinetochore is the protein compound on the chromosome where spindle fibers are attaching in cell division. The centromere is the prime constriction of contract chromosomes conversely kinetochore is a disc shape protein complex closely correlating with centromeres. The centromere is the position of kinetochore assembly while kinetochore is the position of assembly and disassembly of microtubules. Centromeres are observable under the light microscope while kinetochores can only see with the help of an electron microscope. Centromeres contain no layers, but three layers are present in the kinetochore. Corona structure is not present in centromeres while kinetochore contains corona. Centromeres cannot bind with microtubules whereas outer kinetochore consists of about 20 sites for the attachment of kinetochore microtubules. Centromeres can either monocentric or holocentric, but one centromere comprises one kinetochore complex.

Comparison Chart

CentromereKinetochore
Constrict region of DNA on a chromosomeA protein complex, gather on centromeres of chromosomes
Dead or Live
Highly repetitive DNAProtein complex
Visualization
Under the light microscopeUnder the electron microscope
Structure
Consist of centric heterochromatinMade up of a specializing type of histones
Number
Either monocentric or holocentricOne centromere contains one kinetochore complex
Position
Metacentric, submetacentric, acrocentric and telocentricInner kinetochore and the outer kinetochore
Function
Hold two sister chromatids togetherProvide sites for microtubules attachment
Layers
No layer presentThree-layer present
Binding with Microtubules
Cannot bind with microtubules by themselvesConsists of about 20 sites for the fixing of kinetochore microtubules
Corona
No corona presentCorona present

What is Centromere?

The centromere is the region of a replicating chromosome, hold the two sister chromatids together. Cohesion protein complexes are present in between the two sister chromatids, connecting the two copies of the replicating chromosome. The role of the centromere is to offer a site for binding with microtubules through the kinetochore, which is a protein complex gather on the centromere of the chromosome. Two types of centromeres can identify the chromosomes as point centromeres and regional centrosomes. Point centromeres bind with precise proteins to form centromeres. The development of centromere selects a unique DNA arrangement to form the centromere. Regional centromeres also build on the other DNA sequences. It allows spindle fibers to attach to it during the process of mitosis and meiosis. These particular regions comprise non-histone proteins that defend them from endonuclease consumption, and they are unrestricting to nucleosomes. The central role of the centromere is to deliver sites for kinetochores. In eukaryotes, the sizes of the centromeres differ but perform the same function. Most eukaryotes are monocentric centromeres, where the centromere-kinetochore complex forms at a single point on the chromosome. In unicellular organisms, centromeres of multicellular organisms occur embedding within the productive centric heterochromatin. Centromere contains highly specialize repetitive DNA sequences. Centromere only binds with a unique set of proteins. These regions, therefore, chemically different from the rest of the chromosome. Depending on the centromere position chromosomes can dividing into four major types as metacentric, submetacentric, acrocentric and telocentric.

What is Kinetochore?

The kinetochore is a complex of proteins link with the centromere of a chromosome in cell division, to which the microtubules of the spindle attach. Each chromosome contains a kinetochore. In monocentric organisms, a single kinetochore accumulating point can identify, but in holocentric bodies, the assembling of kinetochores can observe along the entire chromosome. Two regions of a kinetochore can identify as inner kinetochore and outer kinetochore. The inner kinetochore contains the two sister chromatids firmly associating with the centromere region. The inner kinetochore contains the two sister chromatids together with securely associating with the centromere region. The outer kinetochore cooperates with the spindle microtubules. The kinetochore is assembling on the surface of the chromosome after the nuclear envelope is broken down. The functions of these complexes are to fix microtubules of the spindle bundle and depolarize them during the cell division. Kinetochores play a significant role in holding two sister chromatids together along with cohesion protein complexes. Many animal cells comprise disc-like kinetochores with three different layers that form on one side of each chromatid. The inner layer of the kinetochore is associating with the centromere while the outer layer relates with microtubules. The function of the middle layer is indefinite. The number of specific microtubules to a kinetochore differs with the species. For example, human kinetochore binds almost with 15 microtubules whereas kinetochore binds with only one microtubule. In individual organisms, kinetochores cannot visualize as proteins disintegrate. Un-attach kinetochores take extending-fibers that comprises many proteins known as the corona. The microtubules associating with kinetochores take long lives.

Key Differences

  1. The centromere is the region of the chromosome which holds two sister chromatids together after the replication of chromosome while kinetochore is the disc shape protein complex of the chromosome that permits spindle strands to attach during the cell division.
  2. Centromeres are visible under the light microscope whereas kinetochores can only see with the help of an electron microscope.
  3. Centromeres contains no corona structure but kinetochore contains corona.
  4. The centromeres cannot bind with the microtubules, but only the kinetochores that are associating with centromeres can bind to microtubules.
  5. Centromeres consist of centric heterochromatin conversely kinetochores are made up of specializing types of histones like CENP-A.
  6. Four centromere positions can identify as metacentric, submetacentric, acrocentric and telocentric on the other hand kinetochores consist of two layers as inner kinetochore and the outer kinetochore.
  7. Centromeres can either monocentric or holocentric on the flip side one centromere contains one kinetochore complex.
  8. Centromeres cannot bind with microtubules by themselves whereas outer kinetochore consists of around 20 sites for the attaching of kinetochore microtubules.

Comparison Video

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Conclusion

Centromere and kinetochore are two types of essentials contributing to the cell division. A centromere is a region of restricting DNA, present in the form of centric heterochromatin which is bordered by pericentric heterochromatin whereas kinetochore is the protein complex on the chromosome where spindle fibers attach during cell division.

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