6 Differences between Centromere and Kinetochore

Chromosome is the structure formed by the condensation of chromatin during cell division. It consists of long DNA strand wrapped around histone proteins. Each chromosome has a primary constriction point called the centromere, which divides the chromosome into two sections, or “arms.” The short arm of is labeled the “p arm” and the long arm of the chromosome is called the “q arm.”

Electron microscopic studies of the centromeric region revealed the presence of a protein complex around the centromere called kinetochore. Kinetochore is the protein complex associated with the centromeric regions of mitotic and meiotic chromosomes. Microtubules attached to the kinetochore during cell division.
Centromere vs Kinetochore
Centromere vs Kinetochore
Centromere
Kinetochore
It is the primary constriction of the condensed chromosome.
Kinetochores are disc shaped protein complexes intimately associated with centromere.
Centromeres are clearly visible with a light microscope as a constricted region on the condensed chromosome
Kinetochrores can only be seen using electron microscope

It is the site of kinetochore assembly

It is the site of assembly and disassembly of microtubules

It is made up of  highly repetitive, condensed AT rich, heterochromatic DNA with
non-histone proteins

Made up of multiple proteins. It has a trilaminar structure. The inner layer is in close contact with condensed centromeric heterochromatin. Microtubules are attached to the outer layer. The middle layer is less dense.

Fibrous corona like structure is absent. It is made up of highly condensed repetitive DNA with some proteins
Fibrous Corona: In the absence of microtubules, a meshwork of fibers, termed the fibrous corona, can be seen to extend from the surface of the outer plate. . The fibrous corona and the outer plate contain the majority of the known Microtubule-interacting proteins (CENP-E, dynein etc) as well as checkpoint proteins (Bub1, Mad2 etc) that monitor the integrity of kinetochore attachments.
Functions of Centromere:
  • Control locus of chromosome segregation during mitosis and meiosis 
  •  t is the site of kinetochore assembly
  • It ensures delivery of one copy of each chromosome to each daughter at cell division.

      Functions of Kinetochore:
  • Kinetochore is the attachment site for spindle microtubule thereby directly involved in the movement of chromosomes during mitosis and meiosis.
  •  It is the site at which motors generate forces to power chromosome movement.
  • It specifies the attachments between the chromosomes and microtubules of the spindle thus essential for accurate chromosome segregation.
  • Unattached kinetochores are also the signal generators for the mitotic checkpoint, which arrests mitosis until all kinetochores have correctly attached to spindle microtubules, thereby representing the major cell cycle control mechanism protecting against loss of a chromosome

References:
  • Appels, R., Morris, R., Gill, B. S., & May, C. E. (2012). Chromosome biology. Springer Science & Business Media.
  • Ugarković, Đ. I. (2009). Centromere-competent DNA: structure and evolution (pp. 53-76). Springer Berlin Heidelberg.
  • Chan, G. K., Liu, S. T., & Yen, T. J. (2005). Kinetochore structure and function. Trends in cell biology, 15(11), 589-598.
  • Cleveland, D. W., Mao, Y., & Sullivan, K. F. (2003). Centromeres and kinetochores: from epigenetics to mitotic checkpoint signaling. Cell, 112(4), 407-421.
  • By Afunguy at English Wikipedia [Public domain], via Wikimedia Commons
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