Discussion of all aspects of cellular structure, physiology and communication.

Harrow
Garter
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Joined: Sat Oct 15, 2011 7:32 pm

I have a question about diffusion of cells. Why would you expect more of a smaller cell to be diffused in the same period of time than a large cell. Is it just because the smaller ones move faster? And also why would you expect a cell with the same volume as a cubic one, but with a different surface area, to be more diffused than the cubic one?

Harrow
Garter
Posts: 3
Joined: Sat Oct 15, 2011 7:32 pm
As you may have noticed I'm somewhat of an amateur at biology.

Harrow
Garter
Posts: 3
Joined: Sat Oct 15, 2011 7:32 pm
In the example with the same volume but different surface area we used a 8x2x1/2 and a 2x2x2.

JackBean
Inland Taipan
Posts: 5694
Joined: Mon Sep 14, 2009 7:12 pm
you mean how quickly some substance will diffuse inside the cell?

It's not about being faster, but being smaller (-> shorter distance). Regarding different shapes, imagine, what's the longest distance from surface to reach each spot inside.
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

aptitude
Coral
Posts: 115
Joined: Sat Sep 10, 2011 12:58 am
The shape of the cell determines the surface area. The greater the surface area, the more area is available for diffusion. The equation for this is called Fick's Law of Diffusion:

J = PA (C2-C1)

Where J is the flux due to diffusion, P is a constant, C2-C1 is the concentration difference and A is the area. So the greater the area, the greater the flux due to diffusion, and the more diffusion will occur.

Therefore, in two cells with the same volume, one cubic and one shaped irregularly, the irregularly shaped cell has a higher diffusion flux because it has a greater surface area.

Hope that helps.

JackBean
Inland Taipan
Posts: 5694
Joined: Mon Sep 14, 2009 7:12 pm
aptitude: but that is only about diffusion through membrane (or something like that), but the question is probably how long will it take to diffuse into whole cell (volume)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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