The physics of biological molecular motors

Thomas, Neil; Thornhill, R. A.

doi:10.1088/0022-3727/31/3/002

Cited by 63 publications

(37 citation statements)

References 94 publications

(109 reference statements)

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“…The values of η for live C. elegans are negative because the organism's tissues are generating rather than dissipating energy [24,32]. We note, however, that the absolute values of tissue viscosity |η| are within the range (10 2 -10 4 Pa s) measured for living cells [26,34].…”

Section: Elegans' Materials Propertiesmentioning

confidence: 83%

“…The active moment generated by the muscle is defined as M a = −(EIκ a + η a I∂κ/∂t), where κ a is a position and time dependent preferred curvature produced by the muscles of the nematode and η a is a positive constant [32]. A simple form for κ a can be obtained by assuming that κ a is a sinusoidal function of time with an amplitude that decreases from the nematode's head to its tail [24].…”

Section: Swimming Modelmentioning

confidence: 99%

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The Effects of Fluid Viscosity on the Kinematics and Material Properties of C. elegans Swimming at Low Reynolds Number

et al. 2010

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The effects of fluid viscosity on the kinematics of a small swimmer at low Reynolds numbers are investigated in both experiments and in a simple model. The swimmer is the nematode Caenorhabditis elegans, which is an undulating roundworm approximately 1 mm long. Experiments show that the nematode maintains a highly periodic swimming behavior as the fluid viscosity is varied from 1.0 to 12 mPa s. Surprisingly, the nematode's swimming speed (∼ 0.35 mm/s) is nearly insensitive to the range of fluid viscosities investigated here. However, the nematode's beating frequency decreases to an asymptotic value (∼ 1.7 Hz) with increasing fluid viscosity. A simple model is used to estimate the nematode's Young's modulus and tissue viscosity. Both material properties increase with increasing fluid viscosity. It is proposed that the increase in Young's modulus may be associated with muscle contraction in response to larger mechanical loading while the increase in effective tissue viscosity may be associated with the energy necessary to overcome increased fluid drag forces.

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Section: Elegans' Materials Propertiesmentioning

confidence: 83%

Section: Swimming Modelmentioning

confidence: 99%

The Effects of Fluid Viscosity on the Kinematics and Material Properties of C. elegans Swimming at Low Reynolds Number

et al. 2010

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“…Figure 5a shows a Monte Carlo simulation (Thomas & Thornhill 1998) Nishiyama et al (2001). Curve A is the unfiltered signal sampled at 100 kHz, whilst curves B and C show filtered data as in (a).…”

Section: Sub-8 Nanometre Stepsmentioning

confidence: 99%

Kinesin: a molecular motor with a spring in its step

Thomas

Imafuku

Kamiya

et al. 2002

Proc. R. Soc. Lond. B

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A key step in the processive motion of two-headed kinesin along a microtubule is the 'docking' of the neck linker that joins each kinesin head to the motor's dimerized coiled-coil neck. This process is similar to the folding of a protein β-hairpin, which starts in a highly mobile unfolded state that has significant entropic elasticity and finishes in a more rigid folded state. We therefore suggest that neck-linker docking is mechanically equivalent to the thermally activated shortening of a spring that has been stretched by an applied load. This critical tension-dependent step utilizes Brownian motion and it immediately follows the binding of ATP, the hydrolysis of which provides the free energy that drives the kinesin cycle. A simple three-state model incorporating neck-linker docking can account quantitatively for both the kinesin force-velocity relation and the unusual tension-dependence of its Michaelis constant. However, we find that the observed randomness of the kinesin motor requires a more detailed four-state model. Monte Carlo simulations of single-molecule stepping with this model illustrate the possibility of sub-8 nm steps, the size of which is predicted to vary linearly with the applied load.

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“…One motivation is the need to develop miniaturized devices in order to utilize energy resources at the microscopic scale [1][2][3]; and another motivation is the desire in understanding the molecular motors in bioengineering and nanotechnology [4,5].…”

Section: Introductionmentioning

confidence: 99%

Power and efficiency performances of a micro thermal Brownian heat engine with and without external forces

Ding¹,

Chen²,

Sun³

2010

Braz. J. Phys.

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Power and efficiency performances of a thermal Brownian heat engine, which consists of Brownian particles moving in a periodic sawtooth potential with and without external forces and contacting with alternating hot and cold reservoirs along the space coordinate, are studied in this paper. The performance characteristics are obtained by numerical calculations. It is shown that due to the heat flow via the change of kinetic energy of the particles, the Brownian heat engine is always irreversible and the efficiency can never approach the Carnot efficiency. The influences of the operation parameters, i.e. barrier height of the potential, asymmetry of the potential and temperature ratio of the heat reservoirs on the power output, the efficiency and the current performances of the Brownian heat engine are investigated in detail by numerical analysis. When there is no external force, the power output versus efficiency characteristic curves are closed loop-shaped ones, which are similar to those of real conventional irreversible heat engines; whereas when the external force is considered, the power output versus efficiency characteristic curves of the heat engine changed into open loop-shaped ones. Furthermore, the limited regions of the external force and barrier height of the potential are explored by analyzing the current property of the model. It is shown that by reasonable choice of the parameters, the Brownian heat engine can be controlled to operate in the optimal regimes.

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The physics of biological molecular motors

Cited by 63 publications

References 94 publications

The Effects of Fluid Viscosity on the Kinematics and Material Properties of C. elegans Swimming at Low Reynolds Number

The Effects of Fluid Viscosity on the Kinematics and Material Properties of C. elegans Swimming at Low Reynolds Number

Kinesin: a molecular motor with a spring in its step

Power and efficiency performances of a micro thermal Brownian heat engine with and without external forces

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