Bacteriophage, genome size

Yeast (Saeeharomyees eerevisiae) has a genome size of 1.21 X 10 bp. If a genomic library of yeast DNA was constructed in a bacteriophage A vector capable of carrying 16-kbp inserts, how many indi-... 

Fig. 2 Viral genome sizes of different Phaeocystis globosa virus isolates (PgV) determined by pulsed-field gel electrophoresis (PFGE). Lane M Lambda concatamers ladder, Lane 1 uninfected culture of P. globosa, Lane 2 PgV-04 (genome size of 175 kb), Lane 3 PgV-12 T (genome size of 465 kb). The small-sized band (approximately 45 kb) as seen in lanes 1-3 correspond to bacteriophages since algal cultures were not axenic...

Note that in Example 7.17, the DNA of bacteriophage X174 is single-stranded, not double-stranded. In this case, the genome size given in kb refers to the number of base pairs in an equivalent duplex form. In progressing from the simple viruses to eukaryotes, the amount of information in the... 

Figure 2. Map of bacteriophage Xgtl8 to Xgt23 vectors in the region of polylinker. Restriction cleavage sites and the amino acids encoded are shown below the map. Details of restriction sites are presented in reference 8. Genome size is 43.7 kbp for Xgtl8 and Xgtl9 and 43.2 kbp for Xgt20 to Xgt23.

The T-odd bacteriophages Tl, T3, T5, and T7 are medium-sized phage with linear duplex DNA genomes. Replication of linear DNA in these and in many other genomes presents a problem. Even if the RNA primer segment is made at the very 3 end of the template strand, there will be a gap in the final replicated strand when the primer is digested out. Since there is no known enzyme that will add to the 3 end of a chain, this gap will remain unfilled. The problem is solved by terminal redundancy, the presence of a common 260-nucleotide... 

Many plasmids and bacteriophages have been ingeniously modified to enhance the delivery of recombinant DNA molecules into bacteria and to facilitate the selection of bacteria harboring these vectors. Plasmids are circular duplex DNA molecules occurring naturally in some bacteria and ranging in size from 2 to several hundred kilobases. They carry genes for the inactivation of antibiotics, the production of toxins, and the breakdown of natural products. These accessory chromosomes can replicate independently of the host chromosome. In contrast with the host genome, they are dispensable under certain conditions. A bacterial cell may have no plasmids at all or it may house as many as 20 copies of a plasmid. 

Pl-derived artificial chromosome. (PAC). One type of vector used to clone DNA fragments (100- to 300-kb insert size average, 150 kb) in Escherichia coli cells. Based on bacteriophage (a virus) PI genome. 

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