This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Cytochrome C of the bacteria has 50% identity of amino acid sequence with that of human. Which of the following is the most conserved parameter in these two proteins? 
Select and explain. 
A. Quaernary structure, B. Teiary structure, C. Amino acid sequence, D. Loop and turn segments
B: Teiary structure
Answer: B: Teiary structure 
Explanation: B i.e. Teiary structure Teiary structure of cytochrome C in bacteria and humans are highly conserved. Pseudomonas (bacterial)cytochrome C differs from eukaryotic (human) cytochrome in- total no. of amino acids- amino acid sequence.Comparison of primary protein structure with the teiary structure revealed that functionally crucial a.a residues fold closely together in teiary structure while they were distant to each other in primary structure.