What is the difference between cdna and genomic clones

In living organisms, most of the DNA resides in tightly coiled structures called chromosomes, located inside the nucleus in each cell. DNA is made up of four different building blocks, called nucleotides, which are each made up of one of four nitrogenous bases demonstrated in Figure 1. These are the purines: guanine G and adenine A , and the pyrimidines: thymine T and cytosine C.

These nucleotides are coupled to a deoxyribose sugar and are able to bind to other deoxyribose sugars via phosphate linkages to form long chains, some of which can be well over ,, molecules long. Since each deoxyribose in a DNA chain is coupled to one of the four nitrogenous bases G, A, T, or C , these long chains can carry information.

Codons are used to call for specific amino acids to be bonded together to form proteins. For instance the codon adenosine-adenosine-guanosine AAG calls for the amino acid lysine lys to be incorporated into a protein molecule. The codon AGG calls for the amino acid arginine arg. There are also codons that, under the right circumstances, call for a protein to begin to be formed start codons , or for a protein chain to be finished stop codons.

Resulting double stranded cDNA are converted into smaller fragments using restriction endonucleases and inserted into suitable vectors. These constructed recombinant molecules are then added into a host organism and grown in a culture medium to produce clones. Fully sliced mature mRNA does not contain introns and regulatory regions.

Therefore non-coding fragments are not present in cDNA libraries unlike in a genomic library. The genomic library represents a population of clones bearing the fragmented total genomic DNA of an organism. A cDNA clone contains only the sequences found in mRNA while the genomic clone contains the sequences of the entire genome. This is the difference between cDNA and genomic library. Reference: 1. Haneef, Deena T KochunniJazir. Stekel, Dov J.

Image Courtesy: 1. There are several gene cloning strategies in recombinant technology. These fragments are ligated into a vector molecules and the collection of recombinant molecules is transferred into host cells, one molecule in each cell. The total number of all DNA molecules makes up the library. A genomic library contains DNA fragments that represent the entire genome of an organism, whereas in case of cDNA library mRNA from an organism or from an organism or from specific cells of an organism are extracted and then complementary DNA cDNAs are prepared from the mRNA in a multistep reaction catalysed by the enzyme reverse transcriptase.

The resulting double stranded DNA fragments are then inserted into a suitable vector and cloned, creating a population of clones called cDNA library. Since, a cDNA library is derived from mRNA, the library contains the coding region of expressed genes only, with no introns or regulatory regions. Such a library lacks the non coding DNA that makes up a large portion of many eukaryotic genomes.

Genomic Library. Thank you so much. You might like Show more. Unknown 2 August at Anonymous 4 August at Anonymous 25 November at The genome of the organism is passed from the next generation to the other. Generally, genomes are made up of a large number of base pairs. As an example, the human genome consists of around 3 billion base pairs. The chromosomes of the human genome are shown in figure 2.

Figure 2: Chromosomes of the Human Genome. Genomic DNA is used in many experiments in molecular biology.