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The effect of NaCl concentration on the activity of yeast cells?
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I've got this test on the above experiment and I know that as the NaCl concentration increases, the activity of the yeast cells falls. Yeast is a unicellulr fugus that has cell wall made of chitin. By placing yeast into solution of NaCl the yeast cell will lose water by osmosis (due to lower WP outside of cell), ultimately leading to plasmolysis. Here the cell surface membrane separates from the cell wall. The cell wall becomes freely permeable and this allows water and ions from the hypertonic solution to fill this space between the cell wall and the cell surface membrane.
The experiment booklet says that yeast has a protein which maintains a low internal conc of Na+ and high internal conc of K+. My teacher has hinted that when asked to explain why the activity falls with increased NaCl concentration, I must concentrate more on the effect of the NaCl on the protein (above), rather than the whole WP explanation.
Of course, the protein has a teriary structure which keeps its shape and is held via a number of bonds, one being the ionic bonds between different R groups of the amino acids. He said that when NaCl is added to water, it disassociates due to thr water being a polar molecule. Oxygen is slightly more negative and Hyrdogen is slightly more positive. They cluster around the NaCl and pull it apart.
But I don't understand how these ions then have an effect on the activity of the yeast cells.
Would I right if I said that the ions fill the space between the cell surface membrane and the cell wall. But then how do these ions have n effect on the protein which maintains a low internal Na+ conc and high internal K+ conc? And then how does this effect the overall activity of the yeast cell?
PLEASE HELP.. MY MEDICINE PLACE AT UNI DEPENDS ON THIS
The experiment booklet says that yeast has a protein which maintains a low internal conc of Na+ and high internal conc of K+. My teacher has hinted that when asked to explain why the activity falls with increased NaCl concentration, I must concentrate more on the effect of the NaCl on the protein (above), rather than the whole WP explanation.
Of course, the protein has a teriary structure which keeps its shape and is held via a number of bonds, one being the ionic bonds between different R groups of the amino acids. He said that when NaCl is added to water, it disassociates due to thr water being a polar molecule. Oxygen is slightly more negative and Hyrdogen is slightly more positive. They cluster around the NaCl and pull it apart.
But I don't understand how these ions then have an effect on the activity of the yeast cells.
Would I right if I said that the ions fill the space between the cell surface membrane and the cell wall. But then how do these ions have n effect on the protein which maintains a low internal Na+ conc and high internal K+ conc? And then how does this effect the overall activity of the yeast cell?
PLEASE HELP.. MY MEDICINE PLACE AT UNI DEPENDS ON THIS
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#2
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#3
(Original post by indiancobra95)
I've got this test on the above experiment and I know that as the NaCl concentration increases, the activity of the yeast cells falls. Yeast is a unicellulr fugus that has cell wall made of chitin. By placing yeast into solution of NaCl the yeast cell will lose water by osmosis (due to lower WP outside of cell), ultimately leading to plasmolysis. Here the cell surface membrane separates from the cell wall. The cell wall becomes freely permeable and this allows water and ions from the hypertonic solution to fill this space between the cell wall and the cell surface membrane.
The experiment booklet says that yeast has a protein which maintains a low internal conc of Na+ and high internal conc of K+. My teacher has hinted that when asked to explain why the activity falls with increased NaCl concentration, I must concentrate more on the effect of the NaCl on the protein (above), rather than the whole WP explanation.
Of course, the protein has a teriary structure which keeps its shape and is held via a number of bonds, one being the ionic bonds between different R groups of the amino acids. He said that when NaCl is added to water, it disassociates due to thr water being a polar molecule. Oxygen is slightly more negative and Hyrdogen is slightly more positive. They cluster around the NaCl and pull it apart.
But I don't understand how these ions then have an effect on the activity of the yeast cells.
Would I right if I said that the ions fill the space between the cell surface membrane and the cell wall. But then how do these ions have n effect on the protein which maintains a low internal Na+ conc and high internal K+ conc? And then how does this effect the overall activity of the yeast cell?
PLEASE HELP.. MY MEDICINE PLACE AT UNI DEPENDS ON THIS
I've got this test on the above experiment and I know that as the NaCl concentration increases, the activity of the yeast cells falls. Yeast is a unicellulr fugus that has cell wall made of chitin. By placing yeast into solution of NaCl the yeast cell will lose water by osmosis (due to lower WP outside of cell), ultimately leading to plasmolysis. Here the cell surface membrane separates from the cell wall. The cell wall becomes freely permeable and this allows water and ions from the hypertonic solution to fill this space between the cell wall and the cell surface membrane.
The experiment booklet says that yeast has a protein which maintains a low internal conc of Na+ and high internal conc of K+. My teacher has hinted that when asked to explain why the activity falls with increased NaCl concentration, I must concentrate more on the effect of the NaCl on the protein (above), rather than the whole WP explanation.
Of course, the protein has a teriary structure which keeps its shape and is held via a number of bonds, one being the ionic bonds between different R groups of the amino acids. He said that when NaCl is added to water, it disassociates due to thr water being a polar molecule. Oxygen is slightly more negative and Hyrdogen is slightly more positive. They cluster around the NaCl and pull it apart.
But I don't understand how these ions then have an effect on the activity of the yeast cells.
Would I right if I said that the ions fill the space between the cell surface membrane and the cell wall. But then how do these ions have n effect on the protein which maintains a low internal Na+ conc and high internal K+ conc? And then how does this effect the overall activity of the yeast cell?
PLEASE HELP.. MY MEDICINE PLACE AT UNI DEPENDS ON THIS
But would it be the fact that the NaCl solution is ionic and can disrupt the ionic bonds of the tertiary structure of the protein by affecting the charges causing the protein to denature (and if some are enzymes decrease activity because lower rate or reactions...?)
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#4
Yeah I think you got that exactly right 
also as the concentrationof NaCl in the solution increases the concentration gradient between thesolution and the cell will be higher, so more and more ions will diffuse intothe cell and cause more proteins (including enzymes) to denature. Also thisaffects enzymes and proteins that are used in respiration hence the respirationrate will go down and less CO2 will be made. hope I’m not too late
also as the concentrationof NaCl in the solution increases the concentration gradient between thesolution and the cell will be higher, so more and more ions will diffuse intothe cell and cause more proteins (including enzymes) to denature. Also thisaffects enzymes and proteins that are used in respiration hence the respirationrate will go down and less CO2 will be made. hope I’m not too late
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#5
Hii
I'm doing this same coursework on Monday, could you tell me what you were asked? If not, did you figure out how ph affects the enzyme activity? So desperate for help
thanks
I'm doing this same coursework on Monday, could you tell me what you were asked? If not, did you figure out how ph affects the enzyme activity? So desperate for help
thanks
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#6
Hi I've got this coursework this week, how did you find it today? What sort of questions were asked or what should i revise? My teachers not gone though it and I need an A* for my degree, so really need to do well, id appreciate any help!! Thanks!
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