Chemoreception of a Two-Dimensional Cell with Multilayer Diffusion
(2023) FYTK02 20222Computational Biology and Biological Physics - Undergoing reorganization
Department of Astronomy and Theoretical Physics - Undergoing reorganization
- Abstract
- Previously, Berg and Purcell found an expression for the diffusion current of particles into a set of receptors in their paper Physics of Chemoreception. These receptors were assumed to be uniformly distributed on a spherical cell's surface and the receptors where idealized as circular patches. For their model, the particles' diffusion constant was the same for all points outside of the cell. In this thesis, a model was made that mimics the scenario when there is a higher density of crowding material close to the cell's surface which would obstruct the particles from moving around. This makes the diffusion constant closer to the cell smaller than the diffusion constant further away. For computational reasons, two-dimensional geometry was... (More)
- Previously, Berg and Purcell found an expression for the diffusion current of particles into a set of receptors in their paper Physics of Chemoreception. These receptors were assumed to be uniformly distributed on a spherical cell's surface and the receptors where idealized as circular patches. For their model, the particles' diffusion constant was the same for all points outside of the cell. In this thesis, a model was made that mimics the scenario when there is a higher density of crowding material close to the cell's surface which would obstruct the particles from moving around. This makes the diffusion constant closer to the cell smaller than the diffusion constant further away. For computational reasons, two-dimensional geometry was considered. The model contained a two dimensional circular cell with diffusion constant D2 within a distance d from the cell's surface and a diffusion constant D1 further away from the cell. For a fully absorbing cell, the diffusion current was obtained both analytically and numerically. Furthermore, for a cell with equidistantly distributed receptors on its surface, where the remaining parts of the surface were perfectly reflecting, the diffusion current was obtained by numerically solving the diffusion equation. It was shown that the placement of receptors affected the diffusion current. Moreover, the ratio between D1 and D2 influenced the number of receptors needed to reach half of the maximum diffusion current. (Less)
- Popular Abstract
- Lets consider a single cell. On the cell's surface, there are receptors which can absorb a specific type of particles. If one of these particles touches a receptor, it is captured and absorbed by the cell. The number of particles that enter the cell for a unit of time is the diffusion current. Previously, Berg and Purcell showed in their paper Physics of Chemoreception that only a small part of the cell needs to be covered by receptors in order to reach half of the maximum diffusion current into a cell. More specifically, depending on the size of the cell and the receptors, it is possible to reach half of the maximum diffusion current when only 1/1000 of the cell's surface is covered by receptors. The diffusion current is at its maximum... (More)
- Lets consider a single cell. On the cell's surface, there are receptors which can absorb a specific type of particles. If one of these particles touches a receptor, it is captured and absorbed by the cell. The number of particles that enter the cell for a unit of time is the diffusion current. Previously, Berg and Purcell showed in their paper Physics of Chemoreception that only a small part of the cell needs to be covered by receptors in order to reach half of the maximum diffusion current into a cell. More specifically, depending on the size of the cell and the receptors, it is possible to reach half of the maximum diffusion current when only 1/1000 of the cell's surface is covered by receptors. The diffusion current is at its maximum when the cell's surface is fully absorbing.
However, it can be that there is organic material attached to the surface of the cell. This can be imagined as some sort of gooey layer covering the cell's surface. If a particle is inside this goo, it will move slower than when it is outside the gooey layer.
In this thesis, I made a model that mimics this scenario with a gooey layer around the cell. The cell's surface was represented by a circle and the particle capturing receptors as patches on the cell's surface. This model was used to investigate how such a gooey layer affects the intake of particles into the cell. Furthermore, the receptors were placed in different positions to see how this, combined with the gooey layer, affects the intake of particles through the receptors on the cell's surface. It was found that when this gooey layer slows down the particles, more receptors are needed in order to reach half the maximum diffusion current. Furthermore, the diffusion current was higher when the receptors where spread out uniformly over the cell than when the receptors were clustered together. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9111870
- author
- Schijf, Steffi LU
- supervisor
- organization
- course
- FYTK02 20222
- year
- 2023
- type
- M2 - Bachelor Degree
- subject
- keywords
- biophysics, chemoreception, receptors, multilayer diffusion, diffusion
- language
- English
- id
- 9111870
- date added to LUP
- 2023-03-07 13:57:40
- date last changed
- 2023-08-30 15:19:03
@misc{9111870,
abstract = {{Previously, Berg and Purcell found an expression for the diffusion current of particles into a set of receptors in their paper Physics of Chemoreception. These receptors were assumed to be uniformly distributed on a spherical cell's surface and the receptors where idealized as circular patches. For their model, the particles' diffusion constant was the same for all points outside of the cell. In this thesis, a model was made that mimics the scenario when there is a higher density of crowding material close to the cell's surface which would obstruct the particles from moving around. This makes the diffusion constant closer to the cell smaller than the diffusion constant further away. For computational reasons, two-dimensional geometry was considered. The model contained a two dimensional circular cell with diffusion constant D2 within a distance d from the cell's surface and a diffusion constant D1 further away from the cell. For a fully absorbing cell, the diffusion current was obtained both analytically and numerically. Furthermore, for a cell with equidistantly distributed receptors on its surface, where the remaining parts of the surface were perfectly reflecting, the diffusion current was obtained by numerically solving the diffusion equation. It was shown that the placement of receptors affected the diffusion current. Moreover, the ratio between D1 and D2 influenced the number of receptors needed to reach half of the maximum diffusion current.}},
author = {{Schijf, Steffi}},
language = {{eng}},
note = {{Student Paper}},
title = {{Chemoreception of a Two-Dimensional Cell with Multilayer Diffusion}},
year = {{2023}},
}