Question

Discuss the function of kinetochores in mitosis. Specifically:a) How microtubules attach sister chromatids to the spindle- discuss the “trial and error” process and how tension ensures correct attachment.b) If the “+” end of microtubules is embedded in the kinetochore, how is depolymerization and microtubule shortening possible in anaphase?

Answer 1

Mitotic chromosome reveals the presence of a proteinaceous , button like structure called kinetochore.

Funchtion of kinetochore is

- it functions as site of attachment of the chromosome to the dynamic microtubules of the mitotic spindle.

Functions as the residence of several motor protein involved in chromosome mobility.

It act as a key component in the signaling pathway of an important mitotic checkpoint.

A )) chromosome movement is faciliated by mitotic spindle . That spindle consit of microtubules and some associated protein. Spindle extend from the centriole on each of two poles. They attach to chromosome and align them and pull the sister chromatid apart. In trial and error process, the mitotic spindle randomly attched to the chromosome and bioriented , then if attached are correct then stablized by the tension exerted on then by opposing microtubules. If their is incorrect attachment, which lack of tension , becomes unstable due to this unstablillty release quickly . And allows other bioreintations chance.

B ) chromosome movement toward the poles is accomplished by a combination of poleward flux, which moves the body of each microtubules toward one of the pole. And simultaneously depolymerization of microtubules at voth end. Depolymerizing kinesins of kinesin family -13 have localized at + end and - end of microtubules which is responsible for depolymerizarion .

Ndc80 protein complex at outer kinetochore plate acts as device that couples the microtubules depolymerization to chromosome segregation. The force required for chromosomes movement is provided by release of strain energy as microtubules depolymerizes. Released energy is utilized by the curled end of depolymerizing protofilaments . Motor protein of kinetochore, sucha s cytoplasmic dynein also have a force - generating role in chromosome movement during anaphase. And this depolymerization also lead to the shortening of microtubules.

Ndeso canfle Colway ridotubule Samuwan Como barbie0000000 Daivaccaro000000000/ రాయని Poonam ROMANTIC Geeches Samom 0 0000 అ cococcuraloooocoo00000000 ఆ > Depothu r S ukuluda , Homosomal fibe. outh plat of kinetochou.