Discuss genetic modifications in plants and animals,
explaining how they are carried out and giving examples
of applications.
The modification of plant and animal genome is carried out to produce organisms having desirable traits. Various unique plant varieties have been generated with the use of genetic modification. These modified varieties may have distinct nutritional values, better yield, or enhanced flavor. The genetically modified animals can serve as a model for the study-specific diseases.
Genetic modification in plants
The plant and animal genome can be modified through the use of recombinant DNA (deoxyribonucleic acid) technology. The Ti plasmid of Agrobacterium tumefaciens contains a T-DNA segment that is transferred into the plant cells during infection. This DNA contains genes for cytokinin, auxin, and opines that are responsible for the formation of crown gall. The T-DNA contains left and right border repeats flanking the gene coding for these plant growth factors. The virulence genes responsible for the transfer of T-DNA are located outside of this region.
A binary vector strategy can be used to transfer the gene of interest into the plant cells. The T-DNA is carried on a small plasmid and the virulence genes are located on a larger plasmid. The growth hormone genes on T-DNA can be replaced with the gene of interest. The transfer of T-DNA is followed by its integration into the plant cell chromosome.
The genetic modification of plants, mediated by Agrobacterium tumefaciens, has been used to delay fruit ripening. The fruit ripening is mediated by several different genes. One such gene encodes the enzyme polygalacturonase which causes the breakdown of the fruit pericarp. As a result, the fruit outer layer becomes soft and edible. The genetic modification of the tomato genome with an anti-sense copy of the polygalacturonase gene has been done to produce tomato varieties having a delayed ripening process. This tomato variety is known as Flavr Savr. The anti-sense copy is permanently integrated into the plant chromosome. The anti-sense copy produces anti-sense RNA (ribonucleic acid) that binds to the sense RNA transcribed from the polygalacturonase gene. A double-stranded RNA intermediate is formed that prevents the expression of the gene and synthesis of polygalacturonase. This results in the delayed ripening of the tomato.
Step by step
Solved in 3 steps
