(i) Polyadenylation: It is the addition of a poly (A) tail to a messenger RNA. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA (mRNA) for translation.
(ii) Lock and key mechanism : This model was proposed by Emil Fisher in 1898. It is also called the template model. According to this model the union of the substrate and the enzyme takes place at the active site, more or less in a manner in which a key fits in a lock and results in the formation of an enzyme substrate complex. As the two molecules are involved, this hypothesis is also known as the concept of inter-molecular fit. The ES complex is highly unstable and almost immediately this complex breaks to produce the end product of the reaction and regenerate the free enzyme. The ES complex results in the release of energy.
(iii) Edible vaccine are the antigenic proteins that induce B-cells to secrete antibodies. Transgenic crop plants can be constructed which produce vaccine to be eaten i.e., edible vaccine on a large scale at low cost. In 1990, first report of production of edible vaccine in tobacco was establish. There are many advantages associated with edible vaccine such as no problem of storage, easy delivery’, low cost of production. These provide similar effects as the recombination vaccines.
(iv) Vascular differentiation : In vascular differentiation, first identify and clone transcripts that are produced in differentiating vascular tissues, then approach gene function by assessing phenotype in plants with loss of function, created by insertion mutagenesis of RNA interference.
(v) A seedless fruit is a fruit developed to possess no mature seeds. As consumption of seedless crops e.g., fruit is generally easier and more convenient, they are considered commercially valuable. Most commercially produced seedless fruits have been developed from plants whose fruits normally contain numerous relatively large hard seeds distributed throughout the flesh of the fruit.
Seedless fruits can develop in one of two ways : either the fruit develops with fertilization (parthenocarpy), or pollination triggers fruit development, but the ovules or embryos abort without producing mature seeds (stenospermocarpy). Seedless banana and watermelon fruits are produced on triploid plants, whose three sets of chromosomes make it very unlikely for meiosis to produce fertile gametes.
One disadvantage of most seedless crops is a significant reduction in the amount of genetic diversity in the species. As genetically identical clones, a pest or disease that affects one individual is likely capable of affecting each of its clones.
