Sugar-phosphate backbone

Definition

The sugar-phosphate backbone is the structural framework of nucleic acids, consisting of alternating sugar and phosphate groups. This backbone is crucial because it provides stability to the DNA or RNA molecule, allowing for the attachment of nitrogenous bases that carry genetic information. The repeating units of deoxyribose sugar and phosphate in DNA or ribose sugar in RNA form a long chain that defines the overall structure and integrity of these essential biomolecules.

5 Must Know Facts For Your Next Test

1. The sugar-phosphate backbone gives DNA its overall structural stability and prevents the strands from breaking easily.
2. In DNA, the sugar component is deoxyribose, while in RNA, it is ribose, affecting how these molecules function in cellular processes.
3. The sequence of bases attached to the sugar-phosphate backbone encodes genetic information and determines traits in living organisms.
4. The sugar-phosphate backbone is formed through phosphodiester bonds, which link nucleotides together and allow for the formation of long chains.
5. During DNA replication, the integrity of the sugar-phosphate backbone is essential for accurately copying genetic information to new daughter strands.

Review Questions

• How does the structure of the sugar-phosphate backbone contribute to the overall stability of nucleic acids?
  • The sugar-phosphate backbone contributes to nucleic acids' stability by providing a strong and durable framework through phosphodiester bonds. These bonds connect the phosphate group of one nucleotide to the sugar of another, creating a robust chain that supports the attached nitrogenous bases. This structural integrity is vital for maintaining the shape and function of DNA and RNA during various cellular processes, including replication and transcription.
• What are the differences between the sugar-phosphate backbones of DNA and RNA, and how do these differences affect their functions?
  • The primary difference between the sugar-phosphate backbones of DNA and RNA lies in their sugar components; DNA contains deoxyribose while RNA contains ribose. This difference affects their stability, with DNA being more stable due to the absence of a hydroxyl group on deoxyribose. Consequently, DNA serves as a long-term storage form of genetic information, while RNA's structure allows for more versatility in functions such as protein synthesis and regulation within cells.
• Evaluate the role of the sugar-phosphate backbone during DNA replication and its importance in ensuring genetic fidelity.
  • During DNA replication, the sugar-phosphate backbone plays a critical role by maintaining the structural integrity necessary for accurate copying of genetic material. As DNA unwinds, enzymes like DNA polymerase synthesize new strands by adding nucleotides complementary to the original template strand. The continuity provided by the sugar-phosphate backbone ensures that the new daughter strands remain intact, which is essential for genetic fidelity as it allows for precise transmission of genetic information from one generation to another.

Related terms

Nucleotide: The basic building block of nucleic acids, made up of a sugar, a phosphate group, and a nitrogenous base.

Double Helix: The shape of DNA, formed by two strands of nucleotides that twist around each other, stabilized by hydrogen bonds between complementary bases.

Phosphodiester Bond: The covalent bond that links the phosphate group of one nucleotide to the sugar of another, forming the sugar-phosphate backbone.