摘要：

This chapter focuses on the study of banding patterns of chromosomes. The advent of molecular hybridization, which revealed the functionally different segments in a eukaryotic chromosome, led to the banding pattern technique. It is based on the principle that single strands of RNA or DNA are able to recognize and pair with their complementary base sequences. This protocol for molecular hybridization, that is, denaturation at the cytological level, if followed by renaturation and staining with different dyes, particularly Giemsa, gives intensely positive reaction at similar segments of chromosomes, which otherwise show repetitive DNA. Various causes have been ascribed to the occurrence of the chromosome bands. Of them, four factors appear to be of particular importance, namely, the occurrence of repetitive DNA, and differences in the base composition of DNA, in the protein components, and in the degree of packing of DNA or DNP-complex. The different banding patterns have been employed in locating marker segments of chromosomes, particularly those with repetitive DNA sequences, in plant and animal systems. Moreover, chromosome banding technique, in its present form, is a synthetic procedure permitting the visualization of molecular sequences at the cellular, vis-à-vis microscopic level.

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