Synthetic biologists are bridging the gap between non-living chemistry and biological life by coaxing artificial systems to perform functions once thought exclusive to living organisms.
Researchers are increasingly moving away from replicating modern biology, instead focusing on the fundamental chemical processes that allow life to replicate, metabolize, and evolve.
Katerina Hlouchová and her team recently reported in a series of studies that a reduced alphabet of just 10 amino acids could support the protein folds used by modern life, Quanta Magazine reported.
By using these simplified building blocks, Hlouchová is investigating whether life’s early development was constrained to the specific molecules found today or if alternative chemical pathways were possible.
“Did life have to happen this way, or could it have happened in different ways?” Hlouchová told Quanta Magazine. She is currently expanding these experiments to test whether totally different amino acids can achieve similar structural stability.
Beyond Modern Biomolecules
While many researchers use modern DNA and proteins as a blueprint, some scientists argue that focusing solely on today’s materials limits our understanding of how life began. “been too focused on what molecules current life works with,” Sijbren Otto, a systems chemist at the University of Groningen, said.
“If you generalize the definition of a gene, you say, ‘OK, it’s a molecule that stores information,’” Otto explained.
His research has moved beyond nucleotides, the building blocks of DNA, to explore whether other structures can pass on information.
In 2010, Otto discovered that synthetic benzene rings could stack like poker chips and self-replicate by maintaining their specific size.
His lab spent the following decade developing these structures to catalyze chemical reactions and eventually form compartments that grow and divide. These “benzene cells” now exhibit basic metabolic functions, though they lack the ability to evolve.
“opens up a whole new world where we just don't have to rely on life that we see today,” Hlouchová said.
Evolution as a Functional Requirement
In July, a research team led by Kate Adamala at the University of Minnesota demonstrated a synthetic cell capable of growth and division. By packing liposomes with DNA replication systems and enzymes, the team observed lifelike behaviors, including a crude form of natural selection where mutations influenced growth rates.
“I wasn’t allowing myself to believe it for a while,” Adamala said regarding the successful replication and division of the synthetic cells.
The project highlights a central debate in synthetic biology: whether life is an on-off switch or a continuum. Otto argues that pinpointing the exact moment chemistry becomes alive is inherently difficult, comparing the transition to the onset of a heat wave. He maintains that if scientists can conceptually map how evolution arises, they can simulate those mechanisms using any prebiotic materials.
Synthetic Cells Lack Natural Evolution and Use Benzene Rings
Can synthetic cells evolve like natural organisms?
Currently, synthetic cells lack true evolution. While researchers like Kate Adamala have engineered “poor man’s evolution” by inducing mutations that affect growth rates, the cells do not yet exhibit the genetic diversity and adaptation characteristic of natural selection.
Why do some scientists use benzene rings instead of DNA?
Researchers like Sijbren Otto use benzene rings to test if information storage and replication are unique to DNA or if other chemical systems can perform the same functions.
This approach aims to identify the fundamental, rather than circumstantial, requirements of life.
Is there a clear definition of when a chemical system becomes alive?
No, the point at which a system becomes alive is considered arbitrary by many in the field. Sijbren Otto notes that life is better understood as a continuum, where chemical systems become increasingly “alive” as they gain the ability to replicate, metabolize, and eventually evolve.
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