Question

(a) Draw the structural formula for the sugar \(\beta\) -D-ribose. (b) Draw the structural formula for the nucleoside adenosine (it consists of \(\beta\) -D-ribose and adenine). (c) Draw the structural formula for the nucleotide adenosine \(5^{\prime}\) -monophosphate.

Short answer

(a) Five-membered ring of ribose with specific hydroxyl placements. (b) Adenosine: ribose linked to adenine. (c) Adenosine 5'-monophosphate: adenosine with a phosphate at C5.

Step-by-step solution

Recognizing Beta-D-Ribose

Beta-D-ribose is a pentose sugar, meaning it has five carbon atoms. In its beta-D form, the hydroxyl group on the first carbon is above the plane of the ring, while the rest of the hydroxyl groups are below. Draw a five-membered ring (a furanose) and place the hydroxyl groups on the correct carbons: OH on carbon 1 is up, OH on carbons 2, 3, and 4 are down.

Drawing Adenosine Structure

Adenosine is formed by attaching the adenine base to a beta-D-ribose through a beta-N-glycosidic bond. Identify the adenine base, which is a purine with a distinctive double-ring structure (six-membered ring fused to a five-membered ring). Connect adenine to the ribose by linking the nitrogen on adenine to the first carbon (anomeric carbon) of ribose.

Constructing Adenosine 5'-Monophosphate

Adenosine 5'-monophosphate includes the nucleoside adenosine and a phosphate group. Add a phosphate group to the fifth carbon of the ribose moiety of adenosine. The phosphate group connects to the sugar through an ester linkage, forming the nucleotide structure.

Key concepts

Beta-D-Ribose

Beta-D-ribose is a fundamental building block in biochemistry. It is a type of sugar, specifically a pentose sugar because it contains five carbon atoms. This sugar is central to the structure of RNA and other important biomolecules. In its structure, Beta-D-ribose forms a five-membered ring, known in chemistry as a furanose.

In the beta form, which is distinct from the alpha form, the hydroxyl group (-OH) on the first carbon atom is oriented above the plane of the ring. The other hydroxyl groups on carbons 2, 3, and 4 rest below the plane.

• This orientation helps ribose to participate in critical biological processes.
• Being a furanose, it is flexible, thus allowing for various molecular interactions.

Adenosine

Adenosine is an important nucleoside formed from beta-D-ribose and adenine. It plays a vital role in cellular energy transfer and signal transduction in the body. The formation of adenosine involves the binding of the adenine base to beta-D-ribose.

Adenine is a purine base, characterized by its distinctive double-ring structure (consisting of a six-membered and a five-membered ring).

• The bond between adenine and ribose is a beta-N-glycosidic bond.
• This bond connects the nitrogen atom from adenine to the first carbon atom (also known as the anomeric carbon) of ribose.

Adenosine 5'-Monophosphate

Adenosine 5'-monophosphate (AMP) is a nucleotide, which means it is a nucleoside attached to one or more phosphate groups.

AMP specifically refers to adenosine with a single phosphate group attached to the fifth carbon of ribose. This phosphate group connects through an ester linkage, forming the complete nucleotide.

• AMP is a crucial component of RNA.
• It also plays an important role in cellular energy storage and release processes, as seen in molecules like ATP.

Pentose Sugar

Pentose sugars are a class of five-carbon sugars critical in nucleic acid structure and function. They can exist in two main forms: ribose and deoxyribose.

Beta-D-ribose is a significant pentose sugar found in RNA and various biochemical pathways.

• Pentose sugars form the backbone of nucleic acids, crucial for proper genetic replication and function.
• The difference between ribose and deoxyribose lies in the presence of an oxygen atom on the second carbon in ribose, which deoxyribose lacks.

Purine Base

Purine bases are one of the two types of nitrogenous bases found in nucleic acids. They feature a double-ring structure, connecting a six-membered and a five-membered ring. Adenine is a common purine base, pivotal for the structure and function of DNA and RNA.

Purines pair with pyrimidines (the other type of nitrogenous base) to establish the double-helix structure of DNA.

• Adenine, a purine, forms the backbone of nucleotides like adenosine.
• These bases are essential for storing and transferring genetic information.