Genomic DNA Probes, Specific Homologous Sequences, DNA Polymorphism, Molecular Maps, Genomic DNA Sequences, Microsatellites, Polyacrylamide Electrophoresis

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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 DNA probes Genomic DNA probes can be either specific for identification of specific homologous sequences in the genome (for diagnostic kits and isolation of genes, etc.) or alternatively these may be random anonymous probes of unknown sequences, which are used for the study of DNA polymorphism andconstruction of molecular maps, without caring about the genomic DNA sequences to which this polymorphism belongs. In other words, genomic DNA probes can be specific or random.
Same will also be true for cDNA probes discussed in the next para. Usually these probes may consist of DNA fragments which can be as small as 50-200 base pairs to as long as several kilobase pairs long. Although specific probes may sometimes also belong to repetitive DNA, like ribosomal DNA, or minisatellites/microsatellites, majority of probes, used for the study of genomic DNA polymorphism and construction of molecular maps, belong to unique DNA. For the preparation of random genomic DNA probes, genomic DNA is first digested with a restriction enzyme that is a frequent cutter (enzymes with a recognition site that is only four base pairs long are frequent cutters because four bases long sites will be relatively more frequent than those with six or eight bases).
The digested DNA may be subjected either to gel/polyacrylamide electrophoresis or to sucrose density gradient centrifugation. In either case, fragments in a specific range (200-500 base pains) are separated, cloned and characterized to be used as molecular probes. If genomic DNA probe of a specific DNA sequence (e.g. ribosomal DNA. or specific gene) is needed, then such a fragment will have to be detected in the DNA digest or in a genomic library by any of a variety of methods that are available. Specific genes, isolated by a variety of methods discussed, can also be used as molecular probes, particularly for the purpose of diagnosis.	Your Ad Here
A DNA fragment to be used as a probe is multiplied in bacterial cells with the help of a vector. From transformed bacteria, the chimeric vector can be obtained and used in one of the following ways: (i) It may be used directly as probe (the presence of vector DNA will not interfere in probe assays, so that it is not really necessary to remove it). (ii) The cloned segment may be separated (or retrieved), by using the same enzyme which was used for cloning. In the latter case, cleaved chimeric vector DNA will be again electrophoresed for separating the inserted segment on the gel. This inserted segment thus retrieved can now be used as a probe. (iii) The chimeric DNA may also be used for PCR, using flanking sequences as primers; the PCR product can be separated and used as a probe.

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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