Cell: Structure and Functions
Cell Cycle and Cell Division
Chromosomes can be counted best at the stage of
Metaphase is the best stage to count the total number of chromosomes in any species and to establish a detailed study of the morphology of the chromosomes. As mitotic cells are easy to obtain, morphological studies are generally based on mitotic metaphase chromosomes. In this stage, the centrioles are at opposite poles of the cell. The homologous chromosome pairs (the bivalents), are tightly coiled and condensed and become arranged on a plane called the metaphase plate or equatorial plate. This plate is equidistant from the poles. Discontinuous fibres radiate out from the two poles and get connected to kinetochores at the surface of the centromere. A kinetochore is complex protein structure and a point where microtubules attach themselves to the chromosome. When the chromosomes get arranged at the metaphase plate, smaller chromosomes get directed towards the centre while the larger ones are peripheral in position on the equator. The centromeres of all the chromosomes lie on the equator forming an apparent plate called metaphasic or equatorial plate while arms are directed towards the poles.
The correct answer is option C.