Biology Forum › Cell Biology › when does osmosis stop
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- February 12, 2018 at 6:56 am #18513
leeroykincaidParticipantI have a question about osmosis that goes a bit deeper than most basic textbooks so I cannot find the answer.Here’s the problem:
Imagine an animal cell, say a red blood cell, in a slightly hypotonic solution. The water starts to flow in osmotically. The concentration of solute in the cell decreases. The cell slowly starts to swell but does not burst.
The question is: Does this water entering increases the pressure on the membrane (similar to turgor in plant cells only less, because the cell can increase in volume – comparable to elastic energy that must be overcome when blowing a baloon…) and does this cause osmosis to stop BEFORE the concentrations come to equilibrum (meaning that cytoplasm still has a bit more solute concentration than outside of cell) or do the concentrations perfectly match?
Thanx in advance.
- February 12, 2018 at 9:55 am #116342claudepaParticipant
Obviously you already know more on osmosis than me. In my mind osmosis stops when concentrations are similar Inside and outside the cell. If this wrong I am ready to change my view of osmosis.
- February 13, 2018 at 6:34 pm #116343leeroykincaidParticipant
I found this, which I think proves my point, but I cannot say i really understand all the math behind it.
http://www.princeton.edu/~akosmrlj/MAE545_S2017/lecture13-14_slides.pdf
- February 13, 2018 at 8:09 pm #116344claudepaParticipant
it seems that the Princeton file also describes equal concentrations Inside and outside
- February 13, 2018 at 8:12 pm #116345leeroykincaidParticipant
Only when water comes out and the cell shrinks… Not when water comes in and the cell starts to swell – then the membrane tension comes into play.
- February 23, 2018 at 3:44 pm #116347Jose M VParticipant
I think cell will burst. Slightly hypotonic = hypotonic to the interior of the cell contents. So water will enter it and burst the cells. However, it depends on the solute concentration of the hypotonic solution and the total number of cells in the solution. If the solute concentration is less and number of cells is high, then an equilibrium will reach, an isotonic condition. So cell will not burst. Otherwise the opposite.
- March 3, 2018 at 4:02 am #116352Jose M VParticipant
There is a small correction.
I think cell will burst. Slightly hypotonic = hypotonic to the interior of the cell contents. So water will enter it and burst the cells. However, it depends on the solute concentration of the hypotonic solution and the total number of cells in the solution. If the solute concentration is nearer to the interior of the cell and the number of cells is high, then an equilibrium will reach, an isotonic condition. So cell will not burst. Otherwise the opposite.
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