Final answer:
A genetic mutation increasing the hydrophobic nature of ion channel transmembrane domains likely leads to decreased ion transport, as it can disrupt the channel's structure and function.
Step-by-step explanation:
If you have isolated a yeast strain with a genetic mutation that increases the hydrophobic nature of the transmembrane domains of one of its ion channels, the probable outcome is decreased ion transport. This is because the transmembrane domains are key to ion channel function, and changes to their hydrophobicity can disrupt the channel's normal conformation and function. An increased hydrophobic nature may make the channel less permeable to ions or potentially disrupt its ability to open or close properly, leading to a decrease in ion transport efficiency.