What is the Difference Between Sugar in DNA and RNA

The main difference between sugar in DNA and RNA is that sugar in DNA is deoxyribose whereas sugar in RNA is ribose.

Sugar in DNA and RNA are two components of nucleic acids, DNA and RNA. Usually, nucleic acids contain pentose sugar, which is cyclic.  

Key Areas Covered

1. What is Sugar in DNA
   • Definition, Characteristics, Importance
2. What is Sugar in RNA
   • Definition, Characteristics, Importance
3. Similarities Between Sugar in DNA and RNA
   • Outline of Common Features
4. Difference Between Sugar in DNA and RNA
   • Comparison of Key Differences

Key Terms

Sugar in DNA, Sugar in RNA

What is Sugar in DNA

Sugar in DNA is the deoxyribose component of the DNA nucleotide. DNA is a polymer of two polynucleotide chains that coil around each other to form a helical structure. The monomeric unit of the DNA polymer is the DNA nucleotide. Generally, each DNA nucleotide is composed of a deoxyribose sugar, a nitrogenous base, and a phosphate group. In addition, the nitrogenous base and the phosphate group are attached to the deoxyribose sugar. Therefore, deoxyribose is the type of sugar that occurs in DNA.

Figure 1: Sugar-Phosphate Backbone in DNA

Furthermore, DNA is a double-stranded molecule that stores biological information. DNA undergoes replication to produce the same copy of the molecule during reproduction. Normally, the backbone of the DNA molecule is a sugar-phosphate backbone. Phosphodiester bonds are responsible for the polymerization of DNA nucleotides to form the polynucleotide chain. More importantly, a phospho-diester bond is a covalent bond that occurs between sugar and a phosphate group of the two DNA nucleotides. This bond occurs between the third and the fifth carbon atoms of the adjacent DNA nucleotides. 2-Deoxyribose is the pentose sugar that occurs in the polynucleotide chain of DNA.        

What is Sugar in RNA

Sugar in RNA is a ribose sugar and this ribose sugar is a five-carbon sugar molecule, a pentose. RNA is also a polymeric molecule with a sugar-phosphate backbone. Similarly, the phosphor-diester bonds occur between the third and the fifth carbon atoms of the adjacent RNA nucleotides. However, RNA nucleotides are the monomeric units of the polymer, RNA. Generally, RNA is a polymeric molecule with various biological roles in the coding, decoding, regulation, and expression of genes. Unlike DNA, RNA occurs in single strands.

Figure 2: Sugar in RNA

Moreover, ribose is the sugar in RNA while in DNA it is 2-deoxyribose. Therefore, the main difference between the sugars in DNA and RNA is the presence of a hydroxyl group in the second carbon molecule of the pentose ring structure. Besides, DNA is made up of DNA nucleotides while RNA is made up of RNA nucleotides. Adenine, guanine, cytosine, and thymine are the four nitrogenous bases that occur in DNA nucleotides. However, in RNA nucleotides, the four nitrogenous bases are adenine, guanine, cytosine, and uracil.

Similarities Between Sugar in DNA and RNA

• Sugar in DNA and RNA is the pentose sugar that occurs in the nucleotides.
• DNA and RNA are polynucleotide chains with a sugar-phosphate backbone.
• The phospho-diester bonds occur between the third and the fifth carbon atoms of the sugar.

Difference Between Sugar in DNA and RNA

Definition

Sugar in DNA refers to the pentose sugar molecule occurring in the sugar-phosphate backbone of DNA, which is deoxyribose, while sugar in RNA refers to the pentose sugar molecule occurring in the sugar-phosphate backbone of RNA, which is ribose.

Type of Pentose Sugar

2-deoxyribose is the type of sugar in DNA while ribose is the type of sugar in RNA.

Chemical Structure

2-Deoxyribose lacks a hydroxyl group in the second carbon atom of the pentose ring, while ribose contains a hydroxyl group in the second carbon atom of the pentose ring.

Conclusion

In brief, sugar in DNA and RNA is the pentose sugar that occurs in the sugar-phosphate backbone of the polynucleotide chains of DNA and RNA. In general, 2-deoxyribose is the sugar that occurs in the polynucleotide chain of DNA while it is ribose in RNA. 2-deoxyribose, which is the sugar in DNA, lacks a hydroxyl group in the second carbon atom of the pentose ring. However, ribose, which is the sugar in RNA, contains a hydroxyl group at the second carbon atom of the pentose ring. More importantly, DNA and RNA are polynucleotides that store biological information, allowing coding, decoding, regulation, and expression of genes. However, the main difference between sugar in DNA and RNA is the presence of a hydroxyl group at the second carbon of the pentose sugar in the sugar-phosphate backbone.

References:

1. “RNA.” Wikipedia, Wikimedia Foundation, 17 Sept. 2022.
2. “DNA.” Wikipedia, Wikimedia Foundation, 28 Aug. 2022.

Image Courtesy:

1. “DNA chemical structure” By Madprime – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “RNA chemical structure ” By en:User:Narayanese – Own Work (CC BY-SA 3.0) via Commons Wikimedia