Consider the drawing of a dinucleotide below. Suppose that the molecule was cleaved with the enzyme spleen phosphodiesterase, which breaks the covalent bond connecting the phosphate to C-5'. After cleavage, to which nucleoside is the phosphate now attached (A or T)?

Key Concepts

Nucleotides and Nucleosides

Nucleotides are the building blocks of nucleic acids, consisting of a phosphate group, a sugar (ribose or deoxyribose), and a nitrogenous base (adenine, thymine, cytosine, or guanine). Nucleosides, on the other hand, are composed of just a sugar and a nitrogenous base, without the phosphate group. Understanding the difference between these two is crucial for analyzing the effects of enzymatic cleavage on nucleic acid structures.

Phosphodiester Bonds

Phosphodiester bonds are the covalent linkages that connect the phosphate group of one nucleotide to the sugar of another, forming the backbone of DNA and RNA. When an enzyme like spleen phosphodiesterase cleaves these bonds, it can alter the structure of the nucleic acid, affecting which nucleoside the phosphate is attached to. Recognizing how these bonds function is essential for understanding the impact of enzymatic activity on nucleic acids.

Enzymatic Cleavage

Enzymatic cleavage refers to the process by which enzymes break specific chemical bonds in molecules. In this case, spleen phosphodiesterase cleaves the bond between the phosphate and the C-5' carbon of a nucleotide. This action can change the identity of the nucleoside to which the phosphate is attached, making it important to know the enzyme's specificity and the resulting molecular structure after cleavage.