Which statement concerning the tautomeric forms of bases such as uracil is CORRECT?
A) The double-lactim form contains a ketone group.
B) The lactam form contains an alcohol group.
C) The lactam form predominates at neutral pH.
D) Formation of the lactim from the lactam is irreversible.
E) The lactim and double-lactim forms are stabilized at high pH.

Question

Quizplus · Accepted Answer

At neutral pH, the lactam form predominates for bases such as uracil. The lactim and double-lactim forms are stabilized at high pH, but this is not the predominant form at neutral pH. The lactam form contains a keto group, not an alcohol group as in choice B. The conversion from lactam to lactim is reversible, not irreversible as in choice D.

Which Statement Concerning the Tautomeric Forms of Bases Such as Uracil