Question

The pentose deoxyribose is found in DNA, whereas __________ is found in RNA.

Short answer

The pentose ribose is found in RNA.

Step-by-step solution

Identify the pentose sugar in DNA

From the exercise, we know that deoxyribose is a pentose sugar found in DNA.

Identify the pentose sugar in RNA

The pentose sugar found in RNA is ribose, which is similar to deoxyribose, but has an additional hydroxyl group (-OH) on the second carbon. This is the key difference between the two sugars and the reason they are found in different types of nucleic acids.

Answer

The pentose sugar found in RNA is ribose.

Key concepts

DNA structure

DNA, or Deoxyribonucleic Acid, is an essential biomolecule that carries genetic information in living organisms. Its structure is often described as a double helix, resembling a twisted ladder. This unique configuration allows it to perform its role efficiently.
DNA consists of two long strands made up of smaller units called nucleotides. Each nucleotide has three components:

• A phosphate group
• A pentose sugar (deoxyribose in the case of DNA)
• A nitrogenous base (Adenine, Thymine, Cytosine, or Guanine)

The alternating phosphate and sugar units form the backbone of the DNA strands. The nitrogenous bases pair between the two strands, with Adenine pairing with Thymine and Cytosine pairing with Guanine, held together by hydrogen bonds. This complementary base pairing is crucial as it ensures the DNA can replicate accurately during cell division.
Overall, the structure of DNA enables it to hold genetic instructions, which are vital for the development, functioning, and reproduction of cells.

RNA structure

RNA, or Ribonucleic Acid, plays a key role in conveying genetic information from DNA to protein synthesis machinery in cells. Unlike DNA, RNA is generally single-stranded, allowing it to fold into complex three-dimensional shapes. These shapes are necessary for its diverse functions in the cell.
Interestingly, RNA also consists of nucleotides, similar to DNA, with several differences:

• A phosphate group
• A pentose sugar (ribose in the case of RNA)
• A nitrogenous base (Adenine, Uracil, Cytosine, or Guanine)

Note the substitution of Uracil for Thymine in RNA. This change allows RNA to interact differently during protein synthesis, although it follows similar base-pairing rules (Adenine with Uracil, and Cytosine with Guanine) when necessary for structure and function.
RNA's simpler structure facilitates its primary roles, including serving as a template for protein synthesis (mRNA), participating in protein synthesis itself (rRNA and tRNA), and performing regulatory functions.

Pentose sugars

Pentose sugars are a class of sugars containing five carbon atoms, crucial in the backbone structure of nucleic acids. In the context of nucleic acids like DNA and RNA, two primary pentose sugars are deoxyribose and ribose.
Deoxyribose is the pentose sugar found in DNA. Its name indicates it is a variation of ribose, specifically missing one oxygen atom on the second carbon (hence, "deoxy-"). This structural difference is small yet significant because it confers stability to the DNA molecule, making it less reactive and more suitable for long-term genetic storage.
Ribose, the pentose sugar present in RNA, has an additional hydroxyl group (-OH) on the second carbon. This slight structural variation enhances RNA's reactivity, allowing it to perform its functions in protein synthesis and regulation efficiently. The presence of ribose makes RNA more versatile but also more prone to degradation compared to DNA.
Understanding these sugars' roles highlights their importance in differentiating the structural and functional properties of DNA and RNA.