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Chromosome Structure and Mitosis
Concepts tested here
- Role of the centromere
All Questions
2005 AIPMT 1 question
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Centromere is required for -The centromere (primary constriction) is the region where the two sister chromatids of a chromosome are held together.
Disc-shaped structures called kinetochores are present on the sides of the centromere.
Spindle fibres attach to the kinetochores; during anaphase the centromeres split and the chromatids are pulled towards the opposite poles by the shortening of these spindle fibres.
So the centromere is required for the movement of chromosomes towards the poles.
Cytoplasmic cleavage is cytokinesis, crossing over occurs between homologous chromatids during prophase I of meiosis, and transcription occurs in genes; none of these needs the centromere.
A chromosome without a centromere (acentric fragment) is lost during cell division because it cannot move to the poles.