a. A human cell is placed in a container of sugar water. Explain what would occur, if the cell membrane is impermeable to sugar.
b. Another cell is placed into a container of sugar water. However, this cell has the capability to allow large molecules such as sugar to pass through. What will occur in this cell when it is placed into the container of sugar water?
c. If you were yo use a really powerful microscope what might you notice about this cell membrane compared to the first one?
d. At first the passage of sugar across the membrane in the cell from Letter B occurs very slowly, but then the sugar starts to pass at a a very fast rate until the balance of sugar in the cell and outside the cell is reached. What caused this to happen, and what is the name given to this process?
a. If the cell membrane is impermeable to sugar, it means that sugar cannot pass through the membrane. In this case, when a human cell is placed in a container of sugar water, no sugar molecules will be able to enter the cell. Since the cell membrane acts as a barrier, the sugar concentration inside the cell will remain low, while the sugar concentration in the surrounding sugar water will be high. This difference in concentration creates a concentration gradient, leading to a process called osmosis.
b. If the cell has the capability to allow large molecules such as sugar to pass through its membrane, it means that the membrane is permeable to sugar. In this scenario, when the cell is placed into the container of sugar water, the sugar molecules will be able to freely cross the cell membrane. Since there is a higher concentration of sugar in the surrounding solution, the sugar will move from the higher concentration outside the cell to the lower concentration inside the cell through a process called diffusion.
c. If you were to use a really powerful microscope to observe the cell membranes, you might notice a difference between the membranes of the two cells. The membrane of the first cell, which is impermeable to sugar, would appear to remain unchanged because the sugar cannot pass through it. On the other hand, the membrane of the second cell, which is permeable to sugar, might show evidence of the sugar molecules passing through. This could be observed as small openings or channels present in the membrane.
d. The slow passage of sugar across the membrane in the second cell initially occurs due to the concentration gradient created by the higher sugar concentration outside the cell. However, as the sugar molecules continue to enter the cell, the sugar concentration inside the cell increases. Eventually, the balance of sugar concentration between the inside and outside of the cell is reached, resulting in equal concentrations on both sides of the membrane. At this point, the movement of sugar molecules across the membrane slows down and stops. The process in which molecules move from an area of higher concentration to an area of lower concentration until equilibrium is reached is called passive transport or facilitated diffusion.