Question

The human chromosomes are divided into 7 groups and "s-e-x" chromosomes. What is the basis of this division? State the significance of karyotype analysis.

Answer 1

Hint: Cytogenetics is based on the isolation and microscopic study of chromosomes, and it is the principal way by which clinicians diagnose chromosomal abnormalities in people. The number and appearance of chromosomes, as well as their length, banding pattern, and centromere position, make up a karyotype.

Complete answer:
We divide chromosomes into groups based on their size, centromere position, and stained banding pattern.
We acquire a jumble of chromosomes when we open a cell during metaphase (when the chromosomes are all condensed in preparation for cell division).
We divide all of these chromosomes into seven categories depending on their length (how long they are) and the position of their centromeres to assist us sort them out (the narrow part that separates the two arms from one another). Some chromosomes contain centromeres in the centre or around the middle, others have them halfway between the middle and the end, and yet others have centrosomes at the very end. When we organise the seven groupings, they appear like this.

Look at Chromosomes 1 and 2 for an example of how chromosomes in the same group can look remarkably similar. The little constriction on the "p" arm of Chromosome 1 distinguishes these. However, this isn't always enough. Take a look at every chromosome in Group C. One of the small indentations can be seen on chromosome 9, but the rest are very similar. We use a technique known as "G-banding" to identify these differences. We break down protein on the chromosomes with enzymes, then add Giemsa dye, which differentially colours them in a banding pattern.

Note:-
The length and position of the centromere divide chromosomes into seven groups, A through G. Each chromosomal group's characteristics will be discussed further down depicts an ideogram or idiogram of human chromosomes, whereas Figure 6 depicts male and female metaphases and karyotypes.