write down the stepwise procedures used for gene mapping give an example as well. Plz answer correctly. It's urgent
Answers
Answer:
Explain why a map is an important aid to genome sequencing
Distinguish between the terms ‘genetic map’ and ‘physical map’
Describe the different types of marker used to construct genetic maps, and state how each type of marker is scored
Summarize the principles of inheritance as discovered by Mendel, and show how subsequent genetic research led to the development of linkage analysis
Explain how linkage analysis is used to construct genetic maps, giving details of how the analysis is carried out in various types of organism, including humans and bacteria
State the limitations of genetic mapping
Evaluate the strengths and weaknesses of the various methods used to construct physical maps of genomes
Describe how restriction mapping is carried out
Describe how fluorescent in situ hybridization (FISH) is used to construct a physical map, including the modifications used to increase the sensitivity of this technique
Explain the basis of sequence tagged site (STS) mapping, and list the various DNA sequences that can be used as STSs
Describe how radiation hybrids and clone libraries are used in STS mapping
Explanation:
DNA sequencing is obviously paramount among these techniques, but sequencing has one major limitation: even with the most sophisticated technology it is rarely possible to obtain a sequence of more than about 750 bp in a single experiment. This means that the sequence of a long DNA molecule has to be constructed from a series of shorter sequences. This is done by breaking the molecule into fragments, determining the sequence of each one, and using a computer to search for overlaps and build up the master sequence (Figure 5.1). This shotgun method is the standard approach for sequencing small prokaryotic genomes, but is much more difficult with larger genomes because the required data analysis becomes disproportionately more complex as the number of fragments increases (for n fragments the number of possible overlaps is given by 2n 2 - 2n). A second problem with the shotgun method is that it can lead to errors when repetitive regions of a genome are analyzed. When a repetitive sequence is broken into fragments, many of the resulting pieces contain the same, or very similar, sequence motifs. It would be very easy to reassemble these sequences so that a portion of a repetitive region is left out, or even to connect together two quite separate pieces of the same or different chromosomes .