Scientists reveal how first cells could have formed on Earth

Understanding how primordial cells emerged during origin of life.


Any hypothesis involving the origins of life must include the prebiotic genesis of protocells. While phospholipid vesicles are well-studied, how fatty-acid-based vesicles emerged is still being determined.

A recent Scripps study provides one possible explanation for how protocells initially evolved and then chemically developed to enable a variety of tasks.

According to the study, phosphorylation—a chemical process in which a molecule receives phosphate groups—might have originated sooner. More structurally intricate, double-chained protocells with a wide range of functions supporting chemical reactions and dividing would result from this. Scientists can better understand how early evolution might have occurred by uncovering the formation process of protocells.

This study could offer a better understanding of the chemical environments of early Earth to uncover the origins of life and how life evolved on early Earth.

In this study, scientists looked at the chemical processes that produced the essential substances and structures on primordial Earth before life began to evolve. They then looked into the possibility that phosphates had a role in the protocell development process. Since phosphates are involved in almost all bodily chemical reactions, Krishnamurthy surmised their presence might have been more ancient than previously thought.

Previously, scientists assumed that fatty acids generate protocells; however, it was obscure how protocells transitioned from a single chain to a double chain of phosphates.

To determine, scientists wanted to mimic plausible prebiotic conditions. They started with identifying three likely mixtures of chemicals that could potentially create vesicles, spherical structures of lipids similar to protocells.

Fatty acids and glycerol, a typical soap-making byproduct that may have existed in the early Earth’s history, were among the compounds employed. They then added other chemicals to make new mixes while watching how these mixtures reacted. These solutions were repeatedly heated and cooled throughout an overnight shake to encourage chemical reactions.

After that, they examined the mixes using fluorescent dyes to see whether vesicle formation had occurred. Scientists occasionally changed the pH and component ratios to learn more about how these variables affected vesicle formation. They also examined how temperature and metal ions affected the vesicles’ stability.

First author Sunil Pulletikurti, a postdoctoral researcher in Krishnamurthy’s lab, said, “The vesicles were able to transition from a fatty acid environment to a phospholipid environment during our experiments, suggesting a similar chemical environment could have existed 4 billion years ago.”

The more stable double-chain structure may have been formed by the phosphorylation of fatty acids and glycerol. Specifically, fatty acid esters formed from glycerol might have produced vesicles with varying sensitivities to pH, temperature, and metal ions—a crucial step in diversified evolution.

Deniz said, “It’s exciting to uncover how early chemistries may have transitioned to allow life on Earth. Our findings also hint at a wealth of intriguing physics that may have played key functional roles to modern cells.”

Journal Reference:

  1. Sunil Pulletikurti et al. We are experimentally modeling the emergence of prebiotically plausible phospholipid vesicles. Chem. DOI: 10.1016/j.chempr.2024.02.007