Chapter 10, Problem 1P

Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book.

The Structure and Ionization Properties of Nucleotides Draw the principal ionic species of occurring at pH 2.

Interpretation Introduction

Interpretation: The principal ionic species of ${\text{5}}^{\text{'}}\text{-GMP}$ that occurs at $\text{pH}$$2$ is to be drawn.

Concept introduction: A nucleotide refers to a basic DNA building block and structural unit. It contains a five-sided sugar, a phosphate group and a nitrogenous base. The nucleotides join together to form a chain of DNA. The nucleotides of DNA and RNA are linked covalently by bridges of the phosphate group. A phosphodiester linkage joins the ${\text{5}}^{\text{'}}$ -hydroxyl group of one nucleotide unit to the next nucleotide’s $3^{\text{'}}$ -hydroxyl group.

Answer to Problem 1P

The principal ionic species of ${\text{5}}^{\text{'}}\text{-GMP}$ that occurs at $\text{pH}$$2$ is,

  

Explanation of Solution

In the polar backbone of DNA and RNA, the phosphate groups are completely ionizable and negatively charged at $\text{pH}$$7$ . At $\text{pH}$$2$ , only one hydrogen of phosphate is dissociated. At this low value of $\text{pH}$ , guanine is hydrogenated. The structure of ${\text{5}}^{\text{'}}\text{-GMP}$ , guanosine monophosphate is found to be different at $\text{pH}$$2$ than at $\text{pH}$$7$ . The hydrogenation of ${\text{5}}^{\text{'}}\text{-GMP}$ at $\text{pH}$$2$ is shown below.

  

  Figure 1