Genomic library

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Genomic library

  1. 1. CONTENTSGenomic library ..........................pg 2DNA library .........................pg 3Genomic lib (intro) ....................pg 4Steps involved .......................pg 5-6Probe .......................pg 7Probe (diagrams) ......................... pg 8-9PCR ........................... pg 10Pcr (intro) ........................... pg 11Pcr invention ............................. pg 12Components ............................. pg13-14Working ......................... pg 15Denaturation ........................ pg 16 0|Page
  2. 2. Annealing ..................... pg 17Elongation ..................... pg 18Review ..................... pg 19Advantage &Disadvantage ..................... pg 20Conclusion ...................... pg 21Blank page ...................... pg 22Glossry ...................... pg 23Sources ....................... pg 24End ........................ pg 25 1|Page
  3. 3. GENOMIC LIBRARY 2|Page
  4. 4. What are DNA libraries?A DNA library is a collection of clones of DNA designed so thatthere is a high probility of finding any particular piece of thesource DNA in the collection.What are the types of DNA libraries?The two types o DNA libraries are: 1. GENOMIC LIBRARY:The genomic library contains DNA fragments representingentire genome of an organism. 2. cDNA LIBRARY:The cDNA library contains only complementry DNA moleculessynthesized from mRNA molecules in a cell. 3|Page
  5. 5. What is genomic library?“A genomic library is a collection of bacteria which have beengenetically engineered to hold the entire DNA of an organism”.A genomic library is a collection of genes or DNA sequencescreated using molecular cloning. These libraries are constructedusing clones of bacteria or yeast that contain vectors into whichfragments of partially digested DNA have been inserted. Thesebacteria and yeast are subsequently grown in culture and whenthese microorganisms replicate their genome, they also replicatethe vector genome contained within them, that is, they replicateDNA fragments that had been inserted in vectors producingclones of the orignal genome.This collection of clones, intheory, contains all sequences found in the original source,including the sequence of interest. Genomic libraries can be constructed using various hosts like plasmids, bacteriophagelambdas , cosmids, YACs and many more. 4|Page
  6. 6. What are the steps involved in theconstruction of genomic library? To create a human genome library, a researcher begins by extracting and purifying DNA from human cell. The purified DNA consist of extremely long strands.To begin working with DNA, the strands must first be cut into manageable sizes. The DNA therefore is digested with restriction enzymes which cut the DNA at specific sequences. The restriction enzyme cut the DNA into 1000s of smaller fragments, each of which may contain one or more gene. Each fragment is different and have unique DNA sequence. To create the library,each fragment must be inserted into loops of DNA called plasmids. A plasmid is a type of vector that allows the DNA to be shuttled in bacteria. The plasmids are digested with the restriction enzymes and then sealed to human DNA using DNA ligase enzymethe resulting molecules are “recombinanat”. 5|Page
  7. 7.  The recombinant DNA molecule are added to bacteria,and the bacteria are made to take up the DNA. When bacteria have taken up the DNA, the entire collection of cells and DNA represents a human genome library. The recombinant plasmids remain separate from the bacteria’s own DNA, making it easy to extract again.What is probe? What is it used for ingenomic library? 6|Page
  8. 8. One of the key elements required to identify a gene duringcloning is a probe. “A probe is normally a cloned piece ofDNA that contains a portion of the sequence for which youare searching”. You typically will make the proberadioactive and add it to a solution. Filters containingimmobilized clones are then bathed in the solution. Theprincipal behind this step is that the probe will bind to anyclone containing sequences similar to those found on theprobe. This binding step is called hybridization. GenomicDNA libraries are almost always screened by hybridizationusing a radioactive nucleic acid probe. 7|Page
  9. 9. “Cloning - specific DNA detection by Hybridization” 1. 8|Page
  10. 10. 2. 3. 9|Page
  11. 11. What are the uses of genomic library?Using a genomic library, researchers can explore thegenome of an organism to learn moreabout genomic structureand function. They can also mapthe genome, identifying the locations of specific genes.This information becomes extremely useful whenresearchers want to develop tests which can be used tolocate genetic variations including mutations which may berelated to congenital conditions. The deeper theunderstanding of an organisms genome, the moreresearchers can know about the organism as a whole.A genomic library can also be used for the purpose ofcloning segments of DNA. The vectors in the host bacteriacan be replicated by the host to create a number of copiesof a segment of interest, with these copies being furtherstudied or inserted into other vectors for geneticmodification and other research purposes. Clonedmaterials, for example, could be inserted into crops for thepurpose of introducing specific modifications with the goalof improving crop performance. 10 | P a g e
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