Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 38

How can P. sibericum be so big yet lifeless? There are several reasons for which viruses are not considered alive nor do they become alive from our perspective. More robust viral species of considerable size have a reasonable probability to incorporate parts of biochemical mechanisms from the infected cells (inside their capsid). Thus, although giants viruses may incorporate functional metabolic pathways of a cell, those functional parts will have nothing to consume since the capsid does not allow the proper exchange of molecules between the interior of the capsid and the outside environment. Those metabolic pathways that can consume component parts inside the capsid may inactivate the virus. Even assuming that there can be a possibility for a primitive metabolism, capsid proteins hinder replication of a possible “new life form.” This is the likely reason why a virus of considerable size lacks the spark of metabolism. But are viruses alive? The virus environment is the cell. Without this environment, viruses become inactive until different stochastic processes lead to reactivation. For cells, the environment is represented by molecules that can be metabolized. Without these substances, cells either decay in simpler macromolecules or enter a hibernation state like viruses do. Therefore, the answer is relative and dependent on our reference system.