Eukaryote, genome size

To secure a gene from a eukaryotic genome, the most efficient method among several is to obtain cDNA (complementary DNA) from mRNA via reverse transcriptase. Use of cDNA avoids dealing with the problem of introns, where a complete gene can stretch over thousands of base pairs but is divided into several small exons, alternating with introns of sometimes remarkable size [several thousand base pairs (kB) for one intron]. As, however, only a few eukaryotic genes are fully sequenced and deposited in one of the databases, one has to rely on ESTs (expressed... 

With many liter-size bio-reactors the planet would still have looked arid to alien visitors. The Genomic Potential Hypothesis will have all of them make proteins in essentially the same way because it is the only way for making proteins efficiently and repeatedly and to remember forever how it was done. If other routes were possible we would see them today, just like we see differences between prokaryotic and eukaryotic genome organization. Versatile as it is, chemistry is not resourceful enough to provide two independent pathways to life. 

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... 

Because the bacterial genome is smaller in size than the eukaryotic genome, nonrepeated sequences in DNA from the former will be present at a higher concentration. Renaturation is a bimolecular reaction and will proceed more quickly when the reactants are at a higher concentration. 

Genome size. As described, most prokaryotic genomes are relatively small with considerably fewer genes than those of eukaryotes. The E. coli chromosome contains about 4.6 megabases (Mb) that code for about 4300 genes. (One Mb is 1 x 106 bases.)... 

DNA SYNTHESIS IN EUKARYOTES Although the principles of DNA replication in prokaryotes and eukaryotes have a great deal in common (e.g., semiconservative replication and bidirectional replicons), they also have significant differences. Not surprisingly, these differences appear to be related to the size and complexity of eukaryotic genomes. 

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