Proteome represents some subset of all possible genes. Justify.
Answers
Nachimuthu Saraswathy, Ponnusamy Ramalingam, in Concepts and Techniques in Genomics and Proteomics, 2011
Review questions and answers
1.
Define a genome map.
A genome map is the graphical description of the location of genes and DNA markers on the genome of an organism.
2.
What are the different types of genome mapping methods?
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Genetic mapping
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Mapping using genes
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Mapping using molecular markers
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Physical mapping
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Restriction mapping
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Cytogenetic mapping
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STS content mapping
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Radiation hybrid mapping
3.
How does a genetic map differ from a physical map?
A genetic map is constructed using recombination frequency calculated from the progenies and it is an indirect method of locating the positions of genes or DNA markers. The unit of measurement is cM, whereas physical mapping pertains to locating the position of DNA sequences directly on the chromosome of a large DNA fragment. The unit of measurement is the base pair.
4.
What are the markers for genetic mapping and physical mapping?
Markers for genetic mapping
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Genes with visible phenotype
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Molecular markers such as RFLP, AFLP and SSR
Markers for physical mapping
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Restriction enzyme sites
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Expressed sequence tags
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cDNA clones
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Any unique DNA sequence
5.
Clone contig mapping is more useful than other physical mapping methods for genome sequencing. Justify the statement.
Clone contigs are prepared from BAC clone libraries. The BAC clones can also be used both for physical mapping and sequencing.
6.
High density mapping is helpful in genome sequence finishing. Validate the statement.
Eukaryotic genomes are large and they contain a sizable portion of repetitive sequences. Genomic DNA is fragmented into a smaller DNA before sequencing; clone assembly produces contigs but not the entire reconstructed genome, i.e. it has many gaps. To close the gaps, it is necessary to have high density maps.
7.
STS map is one of the highest density physical maps. How is this possible?
Thousands of STS markers are available to map on the BAC library clones using highly sensitive clone fingerprinting techniques. Therefore, it is possible to construct a map with one marker in every 100 kbp of the genome.
8.
Restriction mapping is not a better physical mapping technique for larger genome mapping. Why?
When the size of the genome is too large, the number of fragments produced by restriction digestion will increase, and the restricted fragments separated after gel electrophoresis cannot be viewed as discrete bands.