This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Pseudouridine is seen in 
Select and explain. 
A. DNA, B. tRNA, C. rRNA, D. mRNA
B: tRNA
Answer: B: tRNA 
Explanation: Pseudouridine Is Excreted Unchanged No human enzyme catalyzes hydrolysis or phosphorolysis of the pseudouridine (ps) derived from the degradation of tRNA molecules. This unusual nucleotide, therefore, is excreted unchanged in the urine of normal subjects. Pseudouridine was indeed first isolated from human urineRef: Harpers Illustrated Biochemistry, 30th edition, page no: 356