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Question
Gene expression can be controlled with the help of RNA. Explain the method with an example
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Solution
Regulation of Gene expression:
Gene expression refers to the flow of information from DNA to mRNA and then to polypeptide. It can be controlled with the help of RNA using the RNA interference technique.
RNA interference :
In RNA interference, antisense RNA is used to prevent the gene expression.
RNA is a naturally occurring mechanism of silencing of genes. As a result the protein coded by that particular gene is not synthesized.
Naturally this mechanism is used as a defence against the viruses.
In this method the formation of a dsRNA by binding antisense RNA with original mRNA results in the prevention of translation.
The dsRNA cannot be processed by the translation machinery (ribosomes). Hence, the translation of a particular mRNA and the expression of the gene is prevented.
The source of this complementary RNA or antisense RNA is infection by viruses having RNA genome or mobile genetic elements (transposons) that replicate via an RNA intermediate.
Pictorial representation of RNAi:
Example of RNAi:
- Nematode parasites like the root-knot worm, Meloidogyne incognita, attack root cells of plants (tobacco) and grow into large galls or knots, damaging the crop and reducing the yield.
- Gene from M. incognita can be cloned in the Ti plasmid and can be introduced in the Tobacco plant using the Agrobacterium vector.
- Now, Tobacco plants will express antisense RNA for nematode mRNA and form dsRNA.
- It produces both sense and antisense RNA in hosts, resulting in the formation of dsRNA.
- This dsRNA is taken up by the nematode and RNAi is initiated and the particular gene responsible for parasitism is silenced.
- Therefore, the nematode cannot grow in the host plant and the plant gained pest resistance.
Gene expression refers to the flow of information from DNA to mRNA and then to polypeptide. It can be controlled with the help of RNA using the RNA interference technique.
RNA interference :
In RNA interference, antisense RNA is used to prevent the gene expression.
RNA is a naturally occurring mechanism of silencing of genes. As a result the protein coded by that particular gene is not synthesized.
Naturally this mechanism is used as a defence against the viruses.
In this method the formation of a dsRNA by binding antisense RNA with original mRNA results in the prevention of translation.
The dsRNA cannot be processed by the translation machinery (ribosomes). Hence, the translation of a particular mRNA and the expression of the gene is prevented.
The source of this complementary RNA or antisense RNA is infection by viruses having RNA genome or mobile genetic elements (transposons) that replicate via an RNA intermediate.
Pictorial representation of RNAi:
Example of RNAi:
- Nematode parasites like the root-knot worm, Meloidogyne incognita, attack root cells of plants (tobacco) and grow into large galls or knots, damaging the crop and reducing the yield.
- Gene from M. incognita can be cloned in the Ti plasmid and can be introduced in the Tobacco plant using the Agrobacterium vector.
- Now, Tobacco plants will express antisense RNA for nematode mRNA and form dsRNA.
- It produces both sense and antisense RNA in hosts, resulting in the formation of dsRNA.
- This dsRNA is taken up by the nematode and RNAi is initiated and the particular gene responsible for parasitism is silenced.
- Therefore, the nematode cannot grow in the host plant and the plant gained pest resistance.
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