What is the effect on a cell when a transport protein is damaged or missing?

Answer 1

This is too vague of a question to answer appropriately. There are thousands of membrane and non-membrane transport proteins in mammalian cells. If a membrane transport protein is missing, then certain materials cannot enter the cell, and the cell may die. If it is a non-membrane transport protein, then whatever it transports within the cell will not be transported and if will not get to the right place to be used. Again, the cell may die, or if not, it may not function properly. Whoever posed this question should take another look at what an open ended, vague, and unfair question this actually is.