From Genes to Genomes: Concepts and Applications of DNA Technology
Format: PDF / Kindle (mobi) / ePub
The latest edition of this highly successful textbook introduces the key techniques and concepts involved in cloning genes and in studying their expression and variation.
The new edition features:
Increased coverage of whole-genome sequencing technologies and enhanced treatment of bioinformatics.
Clear, two-colour diagrams throughout.
A dedicated website including all figures.
Noted for its outstanding balance between clarity of coverage and level of detail, this book provides an excellent introduction to the fast moving world of molecular genetics.
combine the two most similar OTUs (which would be B and AC) into one OTU (ACB), and calculate a further matrix, now with only two OTUs. The final step is to calculate the average distance from ACB to D, and we have a tree (Figure 9.12), which appears to show the relationships between these OTUs and the genetic distance separating them. The depth of the divergence of each branch is shown as half the distance separating the OTUs – for example, A and C differ by four bases, so each branch is given a
been activated, the first nucleotide, in this case G (with a blocking group), is attached. A second mask is then positioned, to allow activation of positions where the next nucleotide is an A, followed by laser exposure, attachment of A residues (with a blocking group) – and so on. Such an array can contain millions of oligonucleotides on a single chip, and they are therefore of great benefit for screening organisms with larger genomes – either for expression studies, or for screening for
thermostable polymerases are available that do have proofreading ability and can be used in these applications. PCR uses Taq polymerase (or other thermostable DNA polymerases) for the exponential amplification of a DNA fragment from a longer initial template, which could be as long as a whole chromosome. The amplified fragment (amplicon) is defined by two short synthetic oligonucleotides, primers, which are complementary to the opposing DNA strands of the template that is being amplified. This
amplify the corresponding fragment from the genomic DNA of your target organism (Figure 4.11). Nested PCR is often used to add to the power of this approach. You can then sequence this product, to try to confirm that it is indeed derived from the correct gene, and you can use it as a probe for screening a gene library to isolate clones carrying the complete gene. Figure 4.11 Use of conserved sequences to design PCR primers. This approach needs to be treated carefully. One reason why part of a
these regulatory regions, and secondly, the common technologies used to examine their function. 6.2.1 Locating the promoter As we have previously seen, genome sequence data enable you to identify open reading frames that potentially code for proteins. It is also possible to use such data to find the location of potential regulatory regions that will control the rate of transcription for a gene. However, there is a complication to such an approach. As we saw in Chapter 5, alignment of the