Molecular Probes and Gene Libraries

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  Molecular Probes and Gene Libraries

  Genomic DNA Probes

  cDNA Probes

 Synthetic Oligonucleotides as Probes

  RNA Probes OR Riboprobes

  Labelling of Probes

  Radiolabelled Probes

  Nonradioactive Probes - Biotin Labelled Probes

   Dot Blots and Slot Blots

   Applications of Molecular Probes

   Use of Molecular Probes in RFLP - Restriction Fragment Length Polymorphism

   Detection of RFLPs

   RFLP's for Study Purpose

   RFLP Maps and Linkage of RFLPs with Specific Genes

   Isolation of Gene OR Related Sequence

   In Situ Hybridization ISH for Location of Sequences on Chromosomes

   Use of Molecular Probes for Human Health Care

   Use of Molecular Probes in DNA Fingerprinting

   Construction and Screening of Genomic and cDNA Libraries

  Genomic Library by Shotgun Experiment

   cDNA Library from mRNAs

   Colony OR Plaque Hybridization for Screeing of Libraries

  Chromosome Walking and Characterization of Chromosome Segments

   Reverse Genetics and Chromosome Jumping OR Hopping Libraries

Molecular Probes and Gene Libraries

Molecular Probes and Gene Libraries - Molecular probes are small DNA or RNA segments that recognize complementary sequences in DNA or RNA molecules and thus allow identification and isolation of these specific DNA sequences from an organism. Antibodies are also occasionally used as probes to recognize specific protein sequences.

Although, initially, these probes were developed and used for genetic engineering research but are now frequently used for a variety of purposes including diagnosis of infectious diseases, identification of food contaminants, variety of microbiological tests, forensic tests (e.g. fingerprinting of murderers or rapists), etc.

Probes can also be used to identify strains of an organism e.g. varieties of a crop species (a plant breeder likes to have a quick test to identify his variety to maintain his patent or breeder's right, so that a competitor may not use it in another name leading to infringement of rights). For basic studies in molecular biology laboratories, the molecular robes are frequently used for identification and isolation of genes or related sequences.

In theory, any nucleic acid (or rarely protein, e.g. antibody) can be used as probe, provided it can be labelled to permit identification and quantitation of the hybrid molecules formed between the probe and the sequence to be identified. In practice; double and single stranded DNAs, mRNA and other RNA's synthesized in vitro are all used as probes.

DNA/RNA probe assays are faster and sensitive, so that many conventional diagnostic tests for viruses and bacteria involving culturing of the organism, are being fast replaced by antibody and DNA probe assays. While culture tests can take days or even months, molecular probe assays can be performed within few hours or minutes.

Therefore, the use of DNA probes has become today's most sophisticated and sensitive technology for a variety of uses involving biological systems both in basic and applied studies including their commercial use.

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  Digoxigenin Labelled Probes

  Alternative to Biotin and Digoxigenin Labelling

  Amplification of DNA Probe Signals

  Techniques Used in Molecular Probing

 Separation of DNA Fragments using Agarose OR Polyacrylamide

  Separation of Large DNA Molecules

 Southern,Northern and Western Blotting