Chapter 1, Problem 1.73P

Interpretation Introduction

(a)

Interpretation:

From the given segment of a nucleic acid, it is to be determined whether it is a segment of RNA or DNA.

Concept introduction:

The small molecular units from which nucleic acids are made are known as nucleotides. Every nucleotide has three components: a phosphate group, a cyclic sugar and a nitrogenous base. Thus, adjacent nucleotides are connected by a bond between the sugar group of one nucleotide and the phosphate group of another nucleotide. In both RNA and DNA, the backbone of a single strand consists of alternating sugar and phosphate group. In RNA, the sugar group is ribose, whereas, in DNA it is deoxyribose. In the ribose sugar, the $2\text{'}$ carbon atom has one hydrogen and one hydroxyl group attached. While in deoxyribose, the $2\text{'}$ carbon atom has two hydrogen atoms attached. Thus, as the name suggests, deoxyribose has one fewer oxygen atom than ribose, at the $2\text{'}$ carbon.

Interpretation Introduction

(b)

Interpretation:

From the given segment of a nucleic acid, each nucleotide should be circled and named.

Concept introduction:

Nucleotides are distinguished from one another by identifying the nitrogenous bases attached to the sugar group. In both, RNA and DNA, it is the specific sequence of the nitrogenous bases that determines the genetic information that is stored or carried. There are four types of five nitrogenous bases that could be present in RNA and DNA. Uracil, guanine, adenine, cytosine, thymine are the nitrogenous bases present in RNA and DNA. In a nucleotide, the $1\text{'}$ carbon atom of the sugar group becomes directly bonded to nitrogen atom in the above nitrogenous bases.