Where is [Cl\'] normally highest, inside or outside of a cell? How does this compare to [Na*] in a cell? If the membrane became permeable to Cl^-, what direction would Cl^- move based on its chemical gradient? In a healthy person, when the CFTR channel opens, Cl^- moves from the inside of the cell to membranes, and your response to Question 2 as you answer) What direction will water move in this system when the CFTR is open? If the CFTR doesn\'t work correctly due to a mutation, Cl^- movement is blocked and an Inside Cell abnormally thick sticky mucus is produced on the outside of the cell. This mucus clogs the airways in the lungs, and increases the risk of infection by bacteria. Figure 2 illustrates a mutant CFTR channel in the epithelial cells lining the lung. Solution 1. Mostly Chloride and Sodium are present in high concentrations in the extracellular region and low concentration in the intra cellular region. This is the reason behind generation of membrane potential as potassium is present at low concentrations in the extracellular region and higher in intracellular areas. 2. Since the concentration of Chloride is relatively higher in the extracellular region, if the membrane becomes permeable, it would lead to movement of chloride ions from extracellular to intracellular region because of the existing concentration gradient. 3. CFTR channels stand for Cystic fibrosis Transmembrane Conductance Regulator Channels. It is an ABC transporter class protein which conducts chloride ions and water along with thiocynate ions across epithelial cell membranes. It is responsible for carrying out active transport of Chloride ions against the concentration gradient by the use of ATP as well as phosphorylation. That is why the movement of chloride ions is possible against the concentration gradient. 4. The ionic concentration of the mucus slowly increases with the functioning of CFTR channel and this leads to movement of water from the inside to the outside via osmosis..

1. Where is [Cl'] normally highest, inside or outside of a cell? How does this compare to [Na*] in
a cell? If the membrane became permeable to Cl^-, what direction would Cl^- move based on its
chemical gradient? In a healthy person, when the CFTR channel opens, Cl^- moves from the
inside of the cell to membranes, and your response to Question 2 as you answer) What direction
will water move in this system when the CFTR is open? If the CFTR doesn't work correctly due
to a mutation, Cl^- movement is blocked and an Inside Cell abnormally thick sticky mucus is
produced on the outside of the cell. This mucus clogs the airways in the lungs, and increases the
risk of infection by bacteria. Figure 2 illustrates a mutant CFTR channel in the epithelial cells
lining the lung.
Solution
1. Mostly Chloride and Sodium are present in high concentrations in the extracellular region and
low concentration in the intra cellular region. This is the reason behind generation of membrane
potential as potassium is present at low concentrations in the extracellular region and higher in
intracellular areas.
2. Since the concentration of Chloride is relatively higher in the extracellular region, if the
membrane becomes permeable, it would lead to movement of chloride ions from extracellular to
intracellular region because of the existing concentration gradient.
3. CFTR channels stand for Cystic fibrosis Transmembrane Conductance Regulator Channels. It
is an ABC transporter class protein which conducts chloride ions and water along with
thiocynate ions across epithelial cell membranes. It is responsible for carrying out active
transport of Chloride ions against the concentration gradient by the use of ATP as well as
phosphorylation. That is why the movement of chloride ions is possible against the concentration
gradient.
4. The ionic concentration of the mucus slowly increases with the functioning of CFTR channel
and this leads to movement of water from the inside to the outside via osmosis.