Final answer:
The G-banding technique involves staining chromosomes to visualize banding patterns and identify chromosomes based on size and centromere location. A digital image of the chromosomes is obtained and manually arranged into a karyotype.
Step-by-step explanation:
The 'G-banding' technique is used to visualize the distinct and reproducible banding patterns of each chromosome pair in metaphase spreads. First, the chromosomes are stained with a dye, such as Giemsa stain, which results in 400-800 bands along all 23 chromosome pairs. These bands are made up of tightly coiled DNA and condensed proteins. An experienced geneticist can identify each band, and chromosomes are also identified based on size and centromere location.
To obtain the karyotype, the geneticist obtains a digital image of the chromosomes, identifies each chromosome, and manually arranges them into the classic depiction where the homologous pairs are aligned from longest to shortest.