There aare three possible ways to get a gene of interest
- To make it from mRNA
- To isolate it from the chromosome and
- To synthesise it chemically
Genes can be isolated from the chromosomes by cutting the chromosomes on the flanking sites of the gene using special enzymes known as restriction endonucleases. If, however, the genes are small, they can be synthesized in the laboratory. Another very common method of getting the gene is to synthesize it in the laboratory from messenger RNA, using reverse transcriptas this DNA molecule is called complementary DNA (cDNA). Genes can be isolated from the chromosomes by cutting the chromosomes on the flanking sites of the gene using special enzymes known as restriction endonucleases. If, however, the genes are small, they can be synthesized in the laboratory. Another very common method of getting the gene is to synthesize it in the laboratory from messenger RNA, using reverse transcriptas this DNA molecule is called complementary DNA. Cloning of a gene produces many identical copies. Recombinant DNA technology is used when a very large quantity of a gene is required. The use of polymerase chain reaction creates a lesser number of copies within a laboratory test tube.
Cloning of a gene
Cloning of a gene produces many identical copies. Recombinant DNA technology is used when a very large quantity of a gene is required. The use of polymerase chain reaction (PCR) creates a lesser number of copies within a laboratory test tube. Cloning of a gene produces many identical copies. Recombinant DNA technology is used when a very large quantity of a gene is required. The use of polymerase chain reaction creates a lesser number of copies within a laboratory test tube. Genes can be isolated from the chromosomes by cutting the chromosomes on the flanking sites of the gene using special enzymes known as restriction endonucleases. If, however, the genes are small, they can be synthesized in the laboratory. Another very common method of getting the gene is to synthesize it in the laboratory from messenger RNA, using reverse transcriptase this DNA molecule is called complementary DNA.
Recombinant DNA Technology
Recombinant DNA technology popularly known as genetics engineering aims of synthesizing recombinant DNA which contains DNA from two different sources. In order to produce recombinant DNA the following are required. Recombinant DNA technology popularly known as genetics engineering aims of synthesizing recombinant DNA which contains DNA from two different sources. In order to produce recombinant DNA the following are required:
- Molecular scissors to cut out the gene of interest.
- Gene of interest, which is to cloned.
- The gene of interest along with the vector is then introduced into an expression system as a result of which a specific product is made.
- Molecular carrier or vector, on which the gene of interest could be placed.
Molecular scissors: Restriction Endonucleases
These are natural enzymes of bacteria, which they use for their own protection against viruses. The restriction enzyme cuts down the virul DNA, but does no harm to the bacterial chromosomes. They are called restriction enzymes because they restrict the growth of viruses. Bacteria produce a variety of such restriction enzymes, which cut the DNA at very specific sites characterised by specific sequence of four or six nucleotides arranged symmetrically in the reverse order. Such sequence are known as palindromic sequence. In 1970, Hamilton O. Smith at John’s Hopkins University, isolated the first restricted enzyme. So far more than 400 such enzymes have been isolated out of which about 20 are frequently used in recombinant DNA technology.
EcoR1, a commonly used restriction enzyme, cuts double standard DNA when it has this sequence of bases at the cleavage site. Notice, there is now a gap into which a piece of foreign DNA can be placed. A commonly used restriction enzyme, cuts double standard DNA when it has this sequence of bases at the cleavage site. Notice, there is now a gap into which a piece of foreign DNA can be placed. Genes can be isolated from the chromosomes by cutting the chromosomes on the flanking sites of the gene using special enzymes known as restriction endonucleases. If, however, the genes are small, they can be synthesized in the laboratory. Another very common method of getting the gene is to synthesize it in the laboratory from messenger RNA, using reverse transcriptase this DNA molecule is called complementary DNA.
