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Cell The Unit of Life — BIOLOGY STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceBIOLOGYCell The Unit of Life5 Marks
Question
What is a centromere? How does the position of centromere form the basis of classification of chromosomes. Support your answer with a diagram showing the position of centromere on different types of chromosomes.
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Answer


Centromere is a constriction present on the chromosomes where the chromatids are held together. Chromosomes are divided into four types based on the position of the centromere.
  1. Metacentric chromosome
style="margin-left: 40px;">The chromosomes in which the centromere is present in the middle and divides the chromosome into two equal arms is known as a metacentric chromosome.
  • Sub-metacentric chromosome
The chromosome in which the centromere is slightly away from the middle region is known as a sub-metacentric chromosome. In this, one arm is slightly longer than the other.
  1. Acrocentric chromosome
The chromosome in which the centromere is located close to one of the terminal ends is known as an acrocentric chromosome. In this, one arm is extremely long and the other is extremely short.
  1. Telocentric chromosome
The chromosome in which the centromere is located at one of the terminal ends is known as a telocentric chromosome.

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