Due to the acidic nature of ketone bodies, an elevation of ketone bodies in the
ID: 63130 • Letter: D
Question
Due to the acidic nature of ketone bodies, an elevation of ketone bodies in the blood has the effect of lowering blood pH. To determine the effect of blood pH on 3-HBA transport, C14 3-HBA uptake experiments were performed by measuring the velocity of uptake with increasing pH (shown below). These data show that transport is most efficient when the external pH is low. There are 2 potential explanations for this, one of which is much more likely than the other.
The first explanation is that the C14 3-HBA is preferentially transported in the protonated form. The second explanation is that C14 3-HBA is transported in unprotonated form in symport with a hydrogen ion. Of these 2 explanations, the second is physiologically more likely to occur.
Explain why this is. In your answer describe why the first explanation is not likely to occur. Also describe what it means to be transported in symport with a H+ ion and why this transport is more efficient at low pH (6.2) compared to higher pHs. Would the transport be active or passive?
Initial Velocity of 3- HBA uptake (uM/min) 0 9Explanation / Answer
The integral membrane protein that is involved in transport of two different molecules or ions simultaneously across the phospholipid membrane (plasma membrane) is called symporter.
In the given case, the C14 3-HBA prefers symport technique over movement of molecule in protonated form. This is because mostly C14 3-HBA exists in deprotonated form and is a large molecule that cannot simply diffuse through the membrane pores.
In addition, the transport of 3-HBA with H+ ion is more efficient at low pH than high pH because hydrogen ions are formed at low pH.