Question

What are molecular scissors? Where are they obtained from?

Answer 1

The modern biotechnology is based on genetic engineering, it is the technique used to alter the chemistry of genetic material to introduce these into host organisms and thus change the phenotype of the host organisms.

Complete answer:
The techniques of genetic engineering include the phenomenon of creation of recombinant DNA; gene cloning and gene transfer and allows isolating and introducing only one or a set of desirable genes into the target organism. But inserting the desired genes into the host genome is not easy. Firstly, the selection of genes is done, followed by the selection of suitable vectors which can support and incorporate the gene of interest. This gene of interest incorporated with vectors is then introduced into the host organism and shall be maintained to get results.
The genetic engineering or recombinant DNA technology can be accomplished only with the help of the biotechnology tools. Various tools of genetic engineering are used for this purpose, such as restriction enzymes, vectors and host organisms.
Restriction enzymes are also called molecular scissors. These are used to cut DNA from specific sequences. The restriction enzymes play an important role in recombinant DNA technology. These determine the point where the gene of interest is inserted in the vector. Molecular scissors are of two types: endonucleases and exonucleases. Endonucleases are the restriction enzymes which cut the DNA from within and exonucleases cut the DNA from the ends of the DNA. The endonucleases recognize the DNA palindromic sequences and cut at the specific restriction sites which create sticky ends at the point where the DNA is cut. The gene of interest is integrated with the vector’s DNA at these sticky ends with the help of enzyme ligase. These are usually obtained from bacteria.

Note: Every restriction endonucleases enzyme recognizes a specific palindrome sequence in DNA where they cut off the DNA. The palindromic sequences are the groups of letters that form the same words when read from both forward and backward. Therefore, the palindromes in DNA are sequences of base pairs that read the same on the two complementary strands when their orientation of reading is kept the same.