Most of the components of a living cell can now be synthesised in a laboratory. Organic chemists have deciphered the structures of a large number of organic compounds found in several living organisms, from unicellular bacteria to higher plants and animals. They have also worked out how, many of these complex compounds can be synthesised from smaller and simpler compounds in the laboratory.
Can we put together all the components of a living cell and infuse life into it, so that it can carry out its metabolism, perform specific functions assigned to it and can replicateij Can we play Godij
This has been achieved by Craig Venter and his team who created the first artificial life in 2010. It was a brand-new life. Nothing like it existed before in nature. (Venter and his group share the joint credit for independently sequencing three billion letter DNA code of human genome in 2001, parallel to the international effort. Venter was also the first person to get his own genome sequenced in 2007.)
They first selected the bacterium Mycoplasma genitalium, which had 485 protein coding genes but more than 100 could be deleted without affecting its viability or function. However, it had an extremely slow growth rate. They switched over to faster growing M. mycoides. They accurately determined its genome sequence. Based on the information, they chemically synthesised a replica of its genome and inserted it into a cell, whose genome had been removed. The modified cell with the chemically synthesised genome came to life and functioned as a living cell.
According to its creators, it was a brand new artificial species (2010). Its creators embedded their names in watermarks in its DNA along with two quotes, one from James Joyce: “To live, to err, to fall, to triumph, to recreate life out of life” and one from famous quantum physicist, Richard Feynman: “What I cannot create I do not understand.”
Hutchison lll and others (2016) of Venter’s group wanted to determine the smallest genome, which a living cell can have to remain alive and function. They further reduced the genome of Mycoplasmamycoides JCVI-syn1.0 from 1.08 mega base pairs to 531 kilo base pairs (473 genes) and synthesised Mycoplasmamycoides JCVI-syn3.0, which was capable of autonomous replication and form colonies. It almost contained all the genes that were involved in synthesis and processing of macromolecules. Venter declared in 2016 that meaning of life is at least 473 genes for M. mycoides.
No such organism exists in nature, which has such a low complement of genes and is still alive.
Still some secrets remain unsolved: M. mycoidesJCVI-syn3.0 is an experimental organism, a compromise between small genome size and workable growth rate.
It contains almost all the genes involve in synthesis and processing of macromolecules. Surprisingly, it also contains 149 genes with no known biological functions. If these are deleted, the organism does not function. This suggests there are still unsolved riddles that are essential for life.
(Dr Mitra is a former Dean, OUAT, Professor and Researcher. gnmitra@gmail.com )