September 30, 2022

scienceofedu

science of education

A pair of experiments reveal new details regarding the origin of life on Earth

5 min read

One of the central questions in biology is how life first evolved from inanimate matter, known as abiogenesis. It has long been hypothesized that the origin of life on Earth involved the evolution of molecules, floating in the “primordial soup” 4 billion years ago, that assembled themselves into structures that self-replicate. Two recently reported research projects bring us closer to an understanding of possible mechanisms by which that took place.

At the most basic level, a living organism is one that can reproduce itself by incorporating raw materials from its environment (i.e., nutrients) and use these materials to make more or less identical copies of itself. In order for the copies to resemble the original, there must be a recorded pattern, a code, which determines the form of the copies.

All life on Earth is based on two complex molecules: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), which constitute the code by which the information to construct and reproduce an organism is recorded and implemented. Both are composed of chains of chemicals known as nucleotides. Sets of three nucleotides specify a particular amino acid. The sequence of these nucleotide “triplets” in any given DNA or RNA molecule constitutes a code that can specify a series of amino acids which together compose a particular protein. Proteins are a basic building block of living organisms.

Graphic representation of a loop of RNA. Highlighted are the nucleotide bases (green) and the ribose-phosphate backbone (blue). This is a single strand of RNA that folds back upon itself. (Credit: Vossman , via Wikimedia Commons).

DNA is the famous double helix, the structure of which was first discovered by James Watson and Francis Crick. Its structure consists of two parallel strands of nucleotides entwined helically. RNA exists as a single strand of nucleotides, though it can form double strands and thereby replicate itself.

In addition, not only must living organisms reproduce themselves, but they must have the ability to adapt to a changing environment, in other words, to evolve through succeeding generations, classically known by the Darwinian phrase “descent with modification.” Otherwise, if replication were perfect every time, no change would occur, and the pattern would simply be repeated ad infinitum, like the growth of a crystal, and the myriad living organisms that have existed on Earth would never have evolved.

How did these properties originate?

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