creating life in the laboratory
Reproduction: Red blood cells do not have the capacity for reproduction.
Nothing gives a columnist more satisfaction or excitement than readers coming back with critical comments, questions and clarifications. These allow him to then engage in a dialogue with them on the issues raised. This is what has happened with my recent article on creating life in the chemical laboratory (The Hindu, December 11, 2008).
First was the point about how Wohler, when he converted the inorganic molecule ammonium cyanate into the ‘organic’ molecule urea. And this synthesis led him to throw out the notion that certain molecules, termed ‘organic,’ can be made only by ‘vital forces.’
And much later, Miller and Urey showed that amino acids and even some building blocks of the ‘life’ molecule DNA are made by sparking electricity and radiation in a closed glass bulb containing water, ammonia and carbon dioxide.
Dead or lifeless
Commenting on this, a reader noted, correctly, that molecules — be they urea or DNA — are by themselves dead or lifeless.
Another perceptive reader says: “You can’t rejoice that the ‘notion’ of ‘vital forces’ has been thrown out while synthesizing urea and next wonder when ‘life itself’ will be made in the lab. You have to decide whether a molecule of urea is alive, and if not, nothing at all, yet, has been thrown out.
This brings us to the very definition of life itself. In order to call something alive, it needs to do two things.
One is, it should be capable of making more of itself, namely reproduction. And the second is that it should be able to engage in exchange of energy and materials with the environment surrounding it.
These two properties, namely reproduction and metabolism are necessary and sufficient to define a living organism. The operative phrase is ‘necessary and sufficient.’ It is this phrase that disallows the inclusion of viruses into the world of life.
A virus has the information contained within itself for reproduction, in the form of DNA or RNA. But it cannot, by itself, metabolize; it needs a ‘host’ cell for making more of itself. It has to use the machinery of the cell that it attaches itself to. And that cell better be a living one, actively transacting with the environment. Thus a virus is non-living.
Likewise are certain cells that we house and use in our living bodies. Red blood cells are an excellent example. Unlike their neighbours, the white blood cells, they do not have the capacity for reproduction. RBCs do not have the DNA molecule that is necessary for reproduction.
They are thus non-living. Just as a virus is an inert flask that contains the molecular tape necessary for reproduction, red blood cells are inert bags that contain the molecules with which energy exchange or metabolism with the surrounding environment can occur.
Get started
Let us now ask: What if we inject DNA from a virus into a red blood cells, will we now have life? The answer is “not yet.” What we have is more like a motor car, which has the engine and the fuel, but one which is parked in the garage. Just as a car engine needs to be started, the DNA-injected red cell too needs to get started.
And how to do so is the million dollar question. It is this challenge that Dr. Craig Venter is attempting to win with his laboratory-made DNA genome of the microbe M. genitalia.
It is this ‘kick start’ that we are yet to know how to do. And the one who finds a way to do so will have ‘started’ life. Once this cell is made alive, hopefully it would go on by itself with no further help from the scientist who ‘created’ it.
Another reader asked pertinently: if so, did the scientist infuse “vital force” into the dead system? A tentative answer would be: no, he simply repeated what natural forces would have done over 3.5 billion years ago on earth, when radiation or UV light or ionic currents disturbed what is described as ‘the primordial soup’ which contained material akin to the DNA-injected bag of metabolites.
Whether one wishes to call this act as vital force or something else then becomes a matter of belief. But the more immediate and engaging point is that we are quite close to creating such a life form in the laboratory.
Matters become more complex and engaging when we extrapolate such experiments to higher organisms. Bacteria and plants are fine. They do not have brains or a central nervous system; so they do not ‘think’ but are hard-wired to act and respond in defined ways, however complex, creative or even wily these may be. For centuries, we have been creating new plants by grafting and even cloning. Bonsai plants are looked at with artistic appreciation.
But when we turn to animals, which have a central nervous system and an active brain, we enter the realm of learning, decision making, self-awareness, and consciousness.
Even with some animals, we have been selection breeding cats and dogs. But when it comes to primates and humans, we become m ore anthropocentric. We stop back and ask (rightly so) whether it is ethically and morally acceptable.
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