Related Experiment Video
Updated: Jul 16, 2026
09:53
Real-time In Vitro Monitoring of Odorant Receptor Activation by an Odorant in the Vapor Phase
Published on: April 23, 2019
Could humans recognize odor by phonon assisted tunneling?
Jennifer C Brookes1, Filio Hartoutsiou, A P Horsfield
1Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom. j.brookes@ucl.ac.uk
Physical Review Letters
|March 16, 2007
Summary
The sense of smell may use inelastic electron tunneling to detect scent molecules, a novel mechanism consistent with observed olfactory features. This atomic-scale process offers a new paradigm for molecular interactions in biological receptors.
Area of Science:
- Olfactory receptor mechanisms
- Molecular biophysics
- Chemosensation
Background:
- The sense of smell involves sensitive, selective atomic-scale processes at olfactory receptors.
- Current understanding of odorant detection is incomplete, as molecule shape and size alone are insufficient to explain selectivity.
- A novel hypothesis proposes inelastic electron tunneling as a key mechanism for odorant discrimination.
Purpose of the Study:
- To test the physical viability of the inelastic electron tunneling mechanism for olfactory detection.
- To determine if this mechanism is consistent with known physics and observed features of smell.
Main Methods:
- Development and analysis of a simple, general biophysical model.
- Simulation of inelastic electron tunneling mediated by odorant molecules.
- Parameterization of the model using values appropriate for biomolecular systems.
Main Results:
- The proposed inelastic electron tunneling mechanism is physically consistent with biomolecular parameters.
- The model successfully explains critical discrimination observed in olfactory detection.
- Results align with established principles of quantum mechanics and molecular interactions.
Conclusions:
- Inelastic electron tunneling provides a viable physical mechanism for selective odorant detection.
- This mechanism, termed the 'swipe card model,' offers a new paradigm for molecular recognition at receptors.
- Olfactory recognition involves not only molecular shape and size but also quantum electron transfer processes.
Related Concept Videos
01:20Physiology of Smell and Olfactory Pathway
Humans detect odors with the help of specialized cells located in the upper part of the nasal cavity, called olfactory receptor neurons (ORNs). ORNs possess hair-like structures called cilia, which are receptive to sensations from the inhaled air. When an odorant molecule binds to a specific receptor on the cell of the cilia, it leads to a series of events that ultimately cause the ORN to send electrical signals to the olfactory bulb in the brain through the olfactory nerves.
The olfactory...
The olfactory...
01:25Olfaction
The sense of smell is achieved through the activities of the olfactory system. It starts when an airborne odorant enters the nasal cavity and reaches olfactory epithelium (OE). The OE is protected by a thin layer of mucus, which also serves the purpose of dissolving more complex compounds into simpler chemical odorants. The size of the OE and the density of sensory neurons varies among species; in humans, the OE is only about 9-10 cm2.
The olfactory receptors are embedded in the cilia of the...
The olfactory receptors are embedded in the cilia of the...
01:27Tactile and Chemical Senses
Tactile senses encompass touch, temperature, and pain, each mediated by specific receptors. Touch receptors detect mechanical energy or pressure against the skin. Sensory fibers from these receptors enter the spinal cord and relay information to the brain stem. Here, most fibers cross over to the opposite side of the brain. The touch information then moves to the thalamus, which projects a map of the body's surface onto the somatosensory areas of the parietal lobes in the cerebral cortex. This...
01:03Olfactory Receptors: Location and Structure
The process of olfaction, also known as the sense of smell, is a sophisticated chemical response system. The specialized sensory neurons that facilitate this process, known as olfactory receptor neurons, are situated in an upper segment of the nasal cavity, known as the olfactory epithelium. Olfactory sensory neurons are bipolar, with their dendrites extending from the epithelium's apex into the mucus that lines the nasal cavity. Airborne molecules, when inhaled, traverse the olfactory...
01:31Hearing
When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.