This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Which of the following would have no effect on the fuction of the protein product? 
Select and explain. 
A. Glutamine replaced by asparagine, B. Glutamine replaced by alanine, C. Glutamine replaced by glutamate, D. Glutamine replaced by arginine
A: Glutamine replaced by asparagine
Answer: A: Glutamine replaced by asparagine 
Explanation: When glutamine is replaced by asparagine,there is no change in the function. This is conservative or homologous replacement of amino acids. Asparagine and glutamine are both uncharged polar(hydrophilic)amino acids.Thus,when replaced with asparagine there is no change in the polarity or the charge of the peptide/protein. Reference: Lehninger Principles of Biochemistrry 6th edition pg79