Genomic Library by Shotgun Experiments, CLoning Entire Genome, Genomic Clones, Genomic DNA, Endonuclease, Population Chimeric

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Chimeric DNA Molecular Probes and Gene Libraries Chimeric DNA Molecular Probes and Gene Libraries Introduction Restriction Enzymes for Cloning Technique of Restriction Mapping Restriction Clevage and Gel Electrophoresis Construction of a Restriction Map Use of Partial Digests end Labelling and Hybridization in Restriction Mapping Construction of Chimeric DNA Cloning of Plasmid Vectors Directional Cloning of DNA Fragments with Heterologus Protruding Termini Adding Poly dA at 3' Ends of DNA Clone Blunt End Ligation by T4 DNA Ligase Cloning in Phage λ and Cosmid Vectors Cloning in phage λ Vectors Cloning in Cosmid Vectors Hosts for Cloning Vectors Bacteria as Hosts Eukaryotes as Hosts Molecular Probes Preparation of Probes Genomic DNA Probes

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Your Ad Here	Genomic library by shotgun experiment Cloning an entire genome in the form of a library of random genomic clones (without identifying them) is often called a shotgun experiment. In this experiment, genomic DNA is extracted, broken into fragments of reasonable size by a restriction endonuclease and then inserted into a cloning vector to generate a population of chimeric vector molecules. A set of fragments cloned in this manner is called a genomic library. Once such a library is available, then clones can be perpetuated indefinitely in a plasmid vector and retrieved whenever needed for a variety of purposes, including identification and isolation of a gene, when a specific probe is available.
Genomic libraries can be prepared by using a number of restriction endonuc!eases, one at a time, so that fragments of varying sizes having cuts at different places of the genome will be available. However this may lead to cuts at inconvenient places, including sites within a gene, so that fragments having complete genes will be difficult to obtain. In order to overcome this difficulty, we use the following strategy in the shotgun experiment: (i) We use restriction endonucleases, which have long (8bp) recognition sequences, so that such a sequence may be infrequently distributed. (ii) Conditions are used which give only partial digests, so that a particular restriction site is only occasionally cleaved, and long fragments without having any breaks on recognition sites available within a gene can be easily obtained.
The number of fragments representing every sequence of the genome increases with genome size. For instance, for a probability level of 99% that all sequences are present in our library of a species, we may need 1,500 cloned fragments for E. coli, 4,600 for yeast, 48,000 for Drosophila melanogaster, and 8,00,000 for a mammal like human being. Libraries reaching these desired limits have been prepared in all these cases. Construction of a genomic using recombinant DNA technique	Your Ad Here

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c DNA Probes Synthetic Oligonucleotides as Probes RNA Probes or Riboprobes Labelling of Probes Radiolablled Probes Non Radioactive Probes Biotin Labelled Probes Digoxigenin Labelled Probes Alternatives to Biotin and Digoxigenin Labelling Amplification of DNA Probe Signals Techniques Used in Molecular Probing Southern Nothern and Western Blotting Southern Blotting Northern Blotting Western Blotting Dot Blots and Slot Blots Applications of Molecular Probes Construction and Screening of Genomic and cDNA Libraries Genomic Library by Shotgun Experiment cDNA Library from mRNAs Colony or Plaque Hybridization for Screening of Libraries Chromosome Walking and Characterization of Chromosome Segments Chromosome Jumping or Hopping Libraries BAC Libraries and Assembly of BACs into Contigs