No one person is exactly sure about
the origin of life and how living organisms came to be on earth. However, one of the major existing ideas
about how life evolved on earth is explained though the primordial soup theory. The idea of primordial soup states that the
earth’s chemically reduced atmosphere allowed for simple organic compounds to
accumulate in a “soup” (like the ocean) and eventually create complex
polymers. It is thorough these complex
polymers that living organism were developed.
Interestingly, Lane stated that this hypothesis is perfect from the view
of a molecular biologist because this hypothesis provides an explanation for
the idea of replicators such as genes.
These genes made of DNA and RNA can copy themselves and then be passed
down to the next generation. These
passed down traits can then be acted on by natural selection and evolution can
occur. Although the argument for the
primordial soup theory is valid through the context of genetics, Lane states
that this idea does not make proper connections in terms of thermodynamics. In chemical reactions and interactions,
molecules are constantly moving, reacting, or repulsing against other molecules
around it. Therefore, the theory of primordial
soup in terms of thermodynamics is disconnected because it is unreasonable for molecules
to simply sit in a soup and not react.
As Lane stated, “..all life is
sustained by a ‘main reaction’ of a similar type: a chemical reaction that
wants to happen, and releases energy that can be used to power all the
side-reactions that make up metabolism.”
Without chemical reactions there is nothing present to drive the
formation of complex polymers such as the DNA and RNA needed to drive
life. Remarkably, it is this idea of
thermodynamics that leads many, including Lane, to believe that the origin of
life originated oceanic hydrothermal vents.
The superheated and charged minerals/gases as well as alkaline
conditions, allowed for sulphur bacteria to extract hydrogen and attach it to
carbon dioxide to create organic matter.
This reaction then allowed for the bacteria to flourish and establish
the basis of life.
I found this chapter
very interesting because it showed various theories of life from a multitude of
perspectives that I had learned about before. I thought it was very interesting that Lane chose to start his book with the idea of how life must have first evolved because that might be a controversial subject to bring up (especially in the very beginning of a book). However, I also think beginning his book discussing how life first evolved is a unique way to bring readers in and intrigue them to discover even more about how evolution has influenced life on earth. I am excited to see how this theory of the origin of life connects with the
evolution of DNA in the next chapter.
Hey Celina I just wanted to say that I too really liked the emphasis that Lane put on the chemical basis of life. He really stresses how life is dependent on the physical and chemical laws of the universe and that life itself is not any sort of magic that breaks these rules. One question I have is do you think this chapter really counts as evolution because my understanding of evolution defines it as a change in allele frequencies from one generation to the next, so here when life is just beginning does that count as evolution with a different definition or not because at this stage I'm not sure there is DNA let alone different generations. I guess what I'm trying to say is the origin of life an invention of evolution or an event that provided the grounds upon which evolution can act?
ReplyDeleteHi Celina,
ReplyDeleteI really like what you have posted. I comptely agree with what you have to say about this chapter showing the various theories we have all be introduced to before, but i personally had never clicked them together like Lane did in this chapter.
I have a question for you though, do you think that Lane talking about all these theories and inventions but still highly focusing on what we have learned front he Miller-Urey Experiment is the proper way to approach the origin of life. In my opinion he is almost bias to the facts, which is great because its what we do know. But do you think we should acknowledge the other theories more or do you agree with his thinking?