Form and function in biological filaments: A physicist's review

TL;DR

This review explores how biological filaments across various scales utilize physical principles like elasticity and active matter to perform functions such as stability, motion, and complex interactions, linking systems from molecules to animals.

Contribution

It provides a comprehensive overview of the physical mechanisms underlying biological filament functions across multiple length scales, highlighting unifying themes.

Findings

Physical principles like elasticity underpin filament stability and motion.

Active matter non-reciprocity explains dynamic behaviors of filaments.

Cross-scale analysis reveals common design strategies in biological filaments.

Abstract

Nature uses elongated shapes and filaments to build stable structures, generate motion, and allow complex geometric interactions. In this Review, we examine the role of biological filaments across different length scales. From the molecular scale, where cytoskeletal filaments provides a robust but dynamic cellular scaffolding, over the scale of cellular appendages like cilia and flagella, to the scale of filamentous microorganisms like cyanobacteria, among the most successful genera on Earth, and even to the scale of elongated animals like worms and snakes, whose motility modes inspire robotic analogues. We highlight the general mechanisms that couple form and function. We discuss physical principles and models, such as classical elasticity and the non-reciprocity of active matter, that can be used to trace unifying themes linking these systems across about nine orders of magnitude in length.