Mechanical Energy before Chemical Energy at the Origins of Life?

Helen Greenwood Hansma

doi:10.3390/sci2040088

Abstract

Mechanical forces and mechanical energy are prevalent in living cells. This may be because mechanical forces and mechanical energy preceded chemical energy at life’s origins. Mechanical energy is more readily available in nonliving systems than the various forms of chemical energy used by living systems. Two possible prebiotic environments that might have provided mechanical energy are hot pools that experience wet/dry cycles and mica sheets as they move, open and shut, as heat pumps or in response to water movements.

Highlights

IntroductionMechanical forces and mechanical energy are prominent in living systems, at all size scales, from the molecular to the cellular and beyond [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]
Mechanical energy in living systems provides energy in a form that is common in nonliving systems
Why do living systems convert chemical energy to mechanical energy, instead of using chemical energy directly? Perhaps this is because mechanical energy was an original energy source at the origins of life

Summary

Introduction

Mechanical forces and mechanical energy are prominent in living systems, at all size scales, from the molecular to the cellular and beyond [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. Mechanical energy at life’s origins would resemble synthetic mechanochemistry in the lab, because there were no enzymes to carry out the (bio)chemical reactions. Entropic forces could have generated mechanical energy (the product of force and distance), without chemical energy, at life’s origins. ATP and most of the chemical energy sources used by living systems were not available at life’s origins. Mechanical forces, entropic forces, redox reactions—and the sun!—were available for providing energy at life’s origins. The mechanical forces of mechanochemistry are a possible energy source for forming monomers as well as polymers. Some monomers, such as amino acids, may have been present on the early earth, but others, such as nucleotides, were not present and were synthesized in some way/s [25]

Results and Discussion

Moving Mica Sheets

Conclusions