Q. Illustrate Chromosome Structure?

Cytologists have studied chromosome morphology and have pointed out that the most interesting feature about the chromosome structure is the position of the centromere. The centromere or constriction in the length of the chromosome provides information about the relationship of the 2 arms of the chromosome. Thus, depending on the position of the centromere, chromosomes are described as metacentric.

The appearance of the basic chromosome set in a dividing cell is known as the karyotype of the cell. This can be analysed to provide information not only of the chromosome number, bit also about chromosome size, chromosome volume, and type of chromosomes in the cell. This information is used by taxonomists for identifying plants and understanding relationships. The karyotype can be represented diagrammatically as an ideogram or karyogram, and these diagrams can be compared for taxonomic purposes. Another interesting observation is that the absolute size of the chromosomes of a karyotype is fairly constant since it is controlled by the genotype. Taxonomists have found that monocots generally have larger chromosomes than dicots, and that smaller chromosomes are found in hardwood plants in comparison to their herbaceous relatives.