Genomic libraries prokaryotic

Library approaches offer the ability to explore a great variety of time- or spatial-dependent interacting contexts although genomic libraries are more suitable for compact genomes (e.g. prokaryotes), cDNA libraries fit better for genomes with intron/exon stmcture (e.g. metazoans) by providing scientists with appropriate tools to study tissues characteristics, differential PPIs patterns linked to a transient state (e.g. differentiated/undifferentiated tissues) as well as interactions correlated to sickness (healthy/diseased tissues). 

Before we study how genomic libraries are made we first need to understand the differences between the genetic organization in eukaryotic and prokaryotic cells. Bacterial genes are uninterrupted sequences of... 

DNA (section 2.4.1) than eukaryotic RNA (section 2.4.2). The result will be the construction of a collection of cloned DNA fragments propagated in bacteria that is called the genomic library. This library should contain representatives of every sequence in the chromosome of a prokaryotic cell and every expressed gene in the case of a eukaryotic cell. The final step consists of the screening of every recombinant clone to identify the required gene(s). 

The construction of a prokaryotic gene library can be achieved by a technique called shotgun cloning (Fig. 24.4). This involves the purification and partial digestion of the genomic (chromosomal) DNA... 

Now that we have briefly introduced some of the most important tools and techniques of molecularbiology, we can return to the isolation, cloningand identification of genes ofinterest from within prokaryotic genomic DNA or eukaryotic cDNA library sequences. There are two main approaches for this. 

Due to methodological problems it is presently not possible to quantifying those taxa which are determined to be present in clone libraries these problems, that are associated with the extraction of nucleic acids, PCR-primer sensitivity and selectivity, cloning steps, and the dependence of PCR amplificate amount on undeterminable genomic properties, have been summarized [21]. Thus, it is also not possible to decide whether the identified clones belong to a majority or a minority population of the naturally occurring prokaryotes. 

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