1. 10pts. Below is a diagram of a cell with two differently sized molecules at m
ID: 218450 • Letter: 1
Question
1. 10pts. Below is a diagram of a cell with two differently sized molecules at much higher concentration inside the cell than outside of the cell. For each of the scenarios listed, describe what would move and where: a) the membrane is permeable to both molecules, b) the membrane is only permeable to the smaller molecule, c) the membrane is impermeable to both molecules. Now assume that the cell wants to continue bringing in more of both molecules even though the concentration inside is high. d) What would the cell need to do (what process) to force molecules inside against their concentration gradient?Explanation / Answer
a. Permeability is the ability of membrane to allow transport of molecules across it. Molecules diffuse or move from a region of high concentration to a region of low concentration.
The membrane is permeable to both molecules. As the number of molecules outside the cells is less than the number of molecules inside the cell, both the molecules will move from the inside of the cells to the outside, until the concentration of the molecules in the inside and outside equals. This transport does not require an input of energy.
Both large and small molecule will move from the inside of the cell to the outside of the cell.
b. When the membrane is only permeable to the small molecule, the small molecules will move from inside of the cell to the outside of the cell, until the concentration on both sides of the cell membrane is equal. However, the larger molecule will not move across the membrane, maintaining the concentration gradient.
c. An impermeable membrane will not allow the diffusion or movement of any molecules across a concentration gradient. Hence, the large as well as small molecules cannot move across the membrane. There will be no movement of small and large molecules from inside of cell to outside of cell.
d. Active transport mechanism will be required to transport molecules against a concentration gradient. This transport will allow molecules to move from high concentration to a region of low concentration (from outside of cell to inside of cell in this case). Active transport requires input of energy, often in form of ATP, for it to occur.
Carrier proteins may be involved that transport the molecules against a concentration gradient. The Na+=K+ pump is an example of active transport in a cell. Active transport can be primary or secondary. In primary active transport, chemical energy in form of ATP is utilized while in secondary active transport, electrochemical gradient provides the energy.
The cell will utilize active transport to move both the large and small molecules from outside the cell to inside of the cell.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.