ABSTRACT
An individual displays its characteristic 2n chromosome number-half maternal and half paternal. A deviation in either direction (+ or −) results in chromosomal imbalance. Cytological techniques, described in Chapter 2, determine the chromosome constitution of an organism and facilitate recognition of the individual chromosomes. Three terms, namely, karyotype, karyogram, and idiogram, are often referred to in the identication of chromosomes. Karyotype is the number, size, and morphology of a chromosome set of a cell in individual or species (Battaglia, 1994). Karyogram is the physical measurement of the chromosomes from a photomicrograph where chromosomes are arranged in descending order (longest to shortest). An idiogram represents a diagrammatic sketch (interpretive drawing) of the karyogram (Figure 7.1). The classication of chromosomes is based on physical characteristics, such as size of chromosomes, features of telomere, position of kinetochore, secondary constriction, size and position of heterochromatic knobs, and relative length of chromosomes (Figure 7.1).
