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
Glucose is linked to hemoglobin through 
Select and explain. 
A. N linkage, B. O linkage, C. C-C linkage, D. O-H linkage
A: N linkage
Answer: A: N linkage 
Explanation: The glycated hemoglobins are together called HbA1 fraction.Out of this 80% molecules are HbA1c, where glucose is attached to the N -terminal valine of beta chain of hemoglobin. The rest of molecules are HbA1a1, where fructose 1,6-phospate and HbA1a2, where glucose-6-phosphate are attached. REF :DM VASUDEVAN TEXTBBOK ,7th EDITION; Page no :328