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Elizabeth Harnett

Kaitlin Cough

After we put the sodium solution under the slide, we could see white appearing around the membrane about 3 minutes later. Not all of the cells reacted this way: some of them showed no reaction to the sodium, whereas others were more affected. After about five minutes we put in a couple of more drops of the distilled water. This reaction was a lot quicker then the reaction with the sodium: in about a minute the cells already showed signs of "filling" up again and not show the white area around the cell. After about five minutes all of the cells were back to normal, the cells even looked like they were beginning to swell.

So why would the cell membrane pull away from the cell wall when the salt solution was added? It looked like the cell was being "deflated"-maybe it was losing water. The salt was sucking the water out of the cell, which meant that water can move in and out of the cell. The water was moving towards the area where there was a higher concentration of the salt. When we put the water back into the slide, the cell started to fill back up with water.

It seems that is was easier for the water to move in and out of the cell, whereas it was harder for the salt to move across the membrane. We can see that it was easier for water to move in and out of the cell because once we placed the distilled water solution into the slide the cells swelled almost immediately as opposed to when we placed the sodium solution into the slide. This took about three minutes for the water to leave the cell (we knew the water was leaving the cell because it was deflated).