Question

Why are deoxyribonucleic acids called acids? What are the acidic groups in their structure?

Short answer

Answer: DNA is called an acid due to the presence of acidic groups in its structure. These acidic groups come from the phosphate groups present in the nucleotides. The phosphate groups contain negatively charged oxygen atoms, which can donate a proton (H+ ion) to a solution, thus exhibiting acidic behavior. The phosphate groups play an essential role in maintaining the DNA structure by forming strong covalent bonds between adjacent sugar molecules, creating the DNA backbone.

Step-by-step solution

Brief Overview of DNA Structure

Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions for the development and functioning of all known living organisms and viruses. DNA is composed of nucleotides, which are the building blocks of the molecule. Each nucleotide consists of three components: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine).

DNA is an acid due to the presence of phosphate groups

The term "acid" in DNA refers to the presence of acidic groups in its structure. These acidic groups come from the phosphate groups that are present in the nucleotides. The phosphate groups contain negatively charged oxygen atoms, which can donate a proton (H+ ion) to a solution, thus exhibiting acidic behavior.

Role of phosphate groups in forming the DNA structure

The phosphate groups in DNA are essential for maintaining the overall structure of the molecule. They form a bridge between the sugar molecules (deoxyribose) of adjacent nucleotides, creating a strong covalent bond. This is called a phosphodiester bond, and it results in the formation of the DNA backbone. In summary, the presence of phosphate groups in the DNA backbone provides the molecule with negatively charged oxygen atoms that can donate protons, giving DNA acidic properties.