ABSTRACT
The varied phenotypes observed for both unicellular and multicellular organisms result from differences in the genes and alleles that comprise the genomes of each species. However, most cell types of a multicellular organism, such as nerve cells, liver cells, bone cells and blood cells, also show striking phenotypic variations. This is not due to differences in the DNA sequence of the genome but to the differential expression of cell-specific genes during development. In modern biology, accurate analysis of gene expression has become increasingly important not only in improving our understanding of gene and protein functions but also to detect low-level transcripts as part of biotechnological applications or in medical diagnosis (Stein et al., 1997).
