Sat. Jan 22nd, 2022

An elegant ballet Proteins enable modern cells to replicate themselves. During cell division, structural proteins and enzymes coordinate the copying of DNA, the division of cell cytoplasmic contents, and the synchronization of cell membranes. Getting these processes right is crucial because defects can cause abnormal or unusable virgin cells.

Billions of years ago, the same challenge was faced by the first self-regulating membrane bundle of chemicals spontaneously derived from inert matter. But these protocells almost certainly had to replicate without relying on large proteins. How they did it is a key question for astronomers and biochemists studying the origin of life.

“If you remove all the enzymes in the cell, nothing will happen. They are just inert sacks, “he said Anna Wang |, An astronomer at the University of New South Wales in Sydney. “They’re really stable, and that’s kind of the point.”

However, in A recent paper Inside Biophysical JournalRoman Atal, a physicist from the City of Science and Industry in France, and Laurent Schwartz, a cancer biologist at the Paris Public Hospital, have developed a series of mathematical equations to show how the model alone could be sufficient to run a significant portion of the heat replica. Process: The splitting of a protocell into two parts.

Atal thinks that the active chemical and physical processes in early life were probably quite simple, and that thermodynamics alone could therefore play an important role in how life began. He said the kind of basic equations he was working on could spell out some rules that governs how life first appeared.

“Temperature gradients are important for life,” Atal said. “If you can understand a subject, you must be able to write its principles.”

Flipping for fission

In order for primitive cells to divide themselves without complex protein machinery, the process would require a physical or chemical driver. “It’s really about removing a cell from its basic function and thinking, ‘What are the basic physical and chemical principles and how can we mimic it without protein?'” Wang said.

Finding these mechanisms becomes even more challenging when you consider that scientists still cannot agree on the definition of life in general and protocell in particular.

What scientists agree is that protocells must contain some kind of conventional information that they can transmit to female cells, a metabolism that carries out chemical reactions and dissociates a lipid membrane metabolism and inherited information from randomness in the rest of the world. In primitive soups where the outer chemical world was inherently random, the division provided by the lipid membrane could create a field of lower entropy.

In order for a protocell to grow before it splits, it must increase not only the inner volume of the cell but also the surface area of ​​the surrounding membrane. To make two smaller daughter cells with a total volume equal to the parent cell, extra lipids would be needed for their membranes, as their surface area would be larger than their size. The chemical reactions required for the synthesis of these lipids will give energy in the form of heat.

When Atal discussed these ideas with Schwartz, he began to wonder if this energy was enough to drive early cell division. A study in the research literature found that mitochondria (the energy centers of cells, which began billions of years ago as symbiotic bacteria) have slightly higher temperatures than surrounding cells. Atal wanted to know if energy differences could be made in the protocell and whether it was enough to run the fission.

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