Post-lab (cont.); edited from OpenStax Imagine it\'s the late 1800s and an excit
ID: 202196 • Letter: P
Question
Post-lab (cont.); edited from OpenStax Imagine it's the late 1800s and an exciting time in cell biology as litle is known about composition, structure and organization of cells and particularly cel membranes T time, based in part on work conducted on erythrocytes (red blood cells) as early as 17,a De Weer, 2000) he current state of knowledge at this can be summarized as follows Living cels contain fluid. This fluid is separated from the external environment by a visible membrane of unknown · The volume of this fuid can change depending upon the nature of the fluid in which change in volume can cause the cell to either shrink, swell or sometimes The membrane is permeable to water but apparencly not generally to solutes * An example of the kind of data that supported the contention that in Figure 1 jacobs, 1931). Consider the data and answer the questions cell membranes are impermeable to solutes appears that follow 30o concertation 200 Figure 8 Average concentration of dissolved, lef) sodium (Na") and right) potassium (K) ions in live dog erythrocytes (dark gray, mg per 100 cc) and the blood plasma in which the erythrocytes are immersed (ight gray. mg per 100 cc). Ns), Error bars are 95% confidence intervals. Data from Kerr (1929). I. Please describe what the data, in Figure 8 above, suggest about the concentration of a) sodium and b) potassium ions inside dog erythrocytes relative to the surrounding plasma. 2. Data from ocher mammal species reveal a pattern similar to that above (acobs, 1931). Please explain why data like these suggest that cell membranes are impermeable to (at least some) solutes. Pi Sc 3. What would you expect the figures above to look like if the membrane of erythrocytes was permeable to these two solutes? You may wish to draw them here: La Wi GrExplanation / Answer
The data in the above figure suggests that, when the concentration of sodium is high in plasm, it is low in eythrocytes. Also, when the concentration of potassium is low in plasma, it is high in erythrocytes. Also, when concentration of sodium is high in plasma, the concentration of potassium is low in plasma. And, when the concentration of potassium is higher in erythrocytes, sodium concentration reduces in erythrocytes. This means, that in order to maintain the sodium potassium balance in the cell, the cell has to be impermeable to at least one of these. This is because, the inflow and outflow of sodium and potassium occur as a result of the sodium potassium pump, which is a one way pump. When the channels on one end open, only then the solutes from that end would enter. As the channels open, there is deployment of a potassium channel or a sodium channel, such that the solute would travel through that channel one at a time. Hence, the membrane becomes impermeable to the other solute. if the cell becomes permeable to both the solutes at once, there will not be any homeostatic balance mainatained.