Cells are the basic units of all living matter which harness the flow of energy to drive the processes of life. While the biochemical networks involved in energy transduction are well-characterized, the energetic costs and constraints for specific cellular processes remain largely unknown. In particular, what are the energy budgets of cells? What are the constraints and limits energy flows impose on cellular processes? Do cells operate near these limits, and if so how do energetic constraints impact cellular functions? Physics has provided many tools to study nonequilibrium systems and to define physical limits, but applying these tools to cell biology remains a challenge. Physical bioenergetics, which resides at the interface of nonequilibrium physics, energy metabolism, and cell biology, seeks to understand how much energy cells are using, how they partition this energy between different cellular processes, and the associated energetic constraints. Here we review recent advances and discuss open questions and challenges in physical bioenergetics.

细胞是所有生命物质的基本单位，它利用能量流动来驱动生命过程。虽然参与能量转导的生化网络已得到充分表征，但特定细胞过程的能量成本和限制在很大程度上仍然未知。特别是，细胞的能量预算是多少？能量流对细胞过程施加的约束和限制是什么？细胞是否在这些极限附近运行，如果是，能量限制如何影响细胞功能？物理学提供了许多工具来研究非平衡系统和定义物理极限，但将这些工具应用于细胞生物学仍然是一个挑战。物理生物能量学位于非平衡物理学、能量代谢和细胞生物学的界面，旨在了解细胞正在使用多少能量，它们如何在不同的细胞过程之间分配这种能量，以及相关的能量限制。在这里，我们回顾了最近的进展并讨论了物理生物能量学中的开放性问题和挑战。