CYSTIC FIBROSIS 2025 REVIEW
QUESTIONS WITH 100% CORRECT
ANSWERS!!
What is cystic fibrosis?
A recessive genetic disorder of the cystic fibrosis transmembrane conductance regulator.
(Approx. 1900 mutations).
What does the disease effect?
It affects all secretory functions in the pancreas, vas deferens, sweat glands, intestines etc.
however there are treatments which maintain or treat these conditions,
How does cystic fibrosis kill?
By causing lung dysfunction. Secretory functions in the lungs are impaired, making it a perfect
environment for bacteria to live in and hence cause infection.
A healthy individual...
Has a fully functioning cystic fibrosis transmembrane conductance regulator. So expression of
the CFTR is necessary.
In a cystic fibrosis patient...
The cystic fibrosis transmembrane conductance channel is not functioning properly or not
expressed in these patients.
The cystic fibrosis transmembrane conductance conducts...
The movement of chloride and bicarbonate ions. The movement of these ions is electrochemical
gradient dependent.
Draw the structure of the CFTR channel.
Must have two transmembrane structures with NBD1 and R units in between. The NBP2 should
be linked to one of the transmembrane domains where the C terminus is.
, What happens to the R unit when the channel is activated?
The R unit becomes phosphorylated by PKA and ATP. This causes a change in the conformation
of the channel leading to it's opening,
What is the NBD domain?
ATP binds here (both or 1, 2?) and when ATP is hydrolysed the channel closes.
Which way do chloride ions move in a healthy individual when the CFTR channel is open?
In a healthy individual the chloride ions move out of the cells (in the lungs outside the epithelial
cell).
What is the CFTR channel structure based on?
It is proposed in the ABC cassette transporter SAV1866 - hanrahan et al 2012.
What is the normal apical surface liquid in a healthy and CFTR defected patient?
In a normal patient the ASL is 7uM and in a CF patient is 1uM,
What is the consequence of having such a low ASL?
The mucous on the apical membrane lining the airways becomes thick and viscous. This reduces
cilia activity in the airways and therefore leads to bacterial infections.
Explain and draw the formation of ASL and the ion transport involved in a normal
patient?
CFTR is activated by the phosphorylation activity of PKA. This causes a conformational change
in the channel leading to it's opening. When the channel opens, the chloride ions move via their
electrochemical gradient out of the epithelial cell onto the apical membrane. The build up of
chloride ions (negative charge) at the apical membrane causes positively charged sodium ions to
move para cellularly into the apical membrane. This balances the charge the charge and provides
an osmotic gradient. Water moves out of the cells into the apical membrane, providing the ASL.
What regulates excess water at the apical membrane?
QUESTIONS WITH 100% CORRECT
ANSWERS!!
What is cystic fibrosis?
A recessive genetic disorder of the cystic fibrosis transmembrane conductance regulator.
(Approx. 1900 mutations).
What does the disease effect?
It affects all secretory functions in the pancreas, vas deferens, sweat glands, intestines etc.
however there are treatments which maintain or treat these conditions,
How does cystic fibrosis kill?
By causing lung dysfunction. Secretory functions in the lungs are impaired, making it a perfect
environment for bacteria to live in and hence cause infection.
A healthy individual...
Has a fully functioning cystic fibrosis transmembrane conductance regulator. So expression of
the CFTR is necessary.
In a cystic fibrosis patient...
The cystic fibrosis transmembrane conductance channel is not functioning properly or not
expressed in these patients.
The cystic fibrosis transmembrane conductance conducts...
The movement of chloride and bicarbonate ions. The movement of these ions is electrochemical
gradient dependent.
Draw the structure of the CFTR channel.
Must have two transmembrane structures with NBD1 and R units in between. The NBP2 should
be linked to one of the transmembrane domains where the C terminus is.
, What happens to the R unit when the channel is activated?
The R unit becomes phosphorylated by PKA and ATP. This causes a change in the conformation
of the channel leading to it's opening,
What is the NBD domain?
ATP binds here (both or 1, 2?) and when ATP is hydrolysed the channel closes.
Which way do chloride ions move in a healthy individual when the CFTR channel is open?
In a healthy individual the chloride ions move out of the cells (in the lungs outside the epithelial
cell).
What is the CFTR channel structure based on?
It is proposed in the ABC cassette transporter SAV1866 - hanrahan et al 2012.
What is the normal apical surface liquid in a healthy and CFTR defected patient?
In a normal patient the ASL is 7uM and in a CF patient is 1uM,
What is the consequence of having such a low ASL?
The mucous on the apical membrane lining the airways becomes thick and viscous. This reduces
cilia activity in the airways and therefore leads to bacterial infections.
Explain and draw the formation of ASL and the ion transport involved in a normal
patient?
CFTR is activated by the phosphorylation activity of PKA. This causes a conformational change
in the channel leading to it's opening. When the channel opens, the chloride ions move via their
electrochemical gradient out of the epithelial cell onto the apical membrane. The build up of
chloride ions (negative charge) at the apical membrane causes positively charged sodium ions to
move para cellularly into the apical membrane. This balances the charge the charge and provides
an osmotic gradient. Water moves out of the cells into the apical membrane, providing the ASL.
What regulates excess water at the apical membrane?
