To measure the mobility of a protein in a cell membrane in cells that are moving
ID: 66710 • Letter: T
Question
To measure the mobility of a protein in a cell membrane in cells that are moving, you perform an experiment where you fluorescently label a subset of proteins you’re interested in, pull the membrane over to one side by applying a brief electric field, release, and then track the individual protein movement with sophisticated microscopy afterwards. Below is a table of the positions (given in mm) at a variety of time points (given in s) you collect an individual protein AS WELL AS the full cell, which, again, is moving during the course of your experiment.
Time (s)
Protein position x (mm)
Protein position y (mm)
Whole cell x (mm)
Whole cell y (mm)
0
0
0
0
0
0.1
0.013
0.002
0.002
0.002
0.2
0.013
0.021
0.004
0.005
0.3
0.011
0.032
0.01
0.01
Calculate the mean squared displacement for both the protein of interest and the whole cell.
Calculate a 2D diffusion coefficient for both EGFR and the cell. Be mindful of your units.
One way to model this receptor transport is to assume that the receptor movement in the membrane represents diffusion, and the receptor movement due to the movement of the cells can be represented by convection. Solve for the Peclet number for the protein using the diffusion coefficient you calculated in B, the characteristic velocity of the cells as the average cell speed (i.e. the distance traveled for each time point, averaged across all the time points), and the characteristic length as the total displacement that the cell traveled during the time course (i.e. total distance over total time).
Given your result, is receptor transport in a migrating cell dictated by convection or diffusion?
Time (s)
Protein position x (mm)
Protein position y (mm)
Whole cell x (mm)
Whole cell y (mm)
0
0
0
0
0
0.1
0.013
0.002
0.002
0.002
0.2
0.013
0.021
0.004
0.005
0.3
0.011
0.032
0.01
0.01
Explanation / Answer
The mens values
Time (s) Protein position x (mm) MEAN Protein position y (mm)MEAN Whole cell x (mm)MEAN Whole cell y (mm)MEAN 0 0 0 0 0 0.1 0.0565 0.051 0.051 0.051 0.2 0.1065 .205 0.102 0.1025 0.3 0.1555 0.16 0.155 0.155Related Questions
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