4-4.6. Disadvantages of genomic library

•  Genome libraries from eukaryotes having very large genomes contain a lot of DNA which does not code for proteins and also contain non-coding DNA such as repetitive DNA and regulatory regions which makes them less than ideal.

•  Genomic library from a eukaryotic organism will not work if the screening method requires the expression of a gene.

4-4.7. Applications

•  To determine the complete genome sequence of a given organism.

•  To study and generate transgenic animals through genetic engineering, serving as a source of genomic sequence.

•  To study the function of regulatory sequences in vitro.

•  To study the genetic mutations.

•  Used for genome mapping, sequencing and the assembly of clone contigs.

4-4.8 Comparison of Genomic and cDNALibraries

cDNA library has revolutionized the field of molecular genetics and recombinant DNA technology. It consists of a population of bacterial transformants or phage lysates in which each mRNA isolated from an organism is represented as its cDNA insertion in a vector. cDNA libraries are used to express eukaryotic genes in prokaryotes. In addition, cDNAs are used to generate expressed sequence tags (ESTs) and splices variant analysis.

Some of the differences of cDNA library with genomic library are presented in Table 4-4.8.