key term - Sugar-phosphate backbone

Definition

The sugar-phosphate backbone is a structural framework of nucleic acids, consisting of alternating sugar and phosphate groups. This backbone provides stability and support for the attached nitrogenous bases, which carry the genetic information in DNA and RNA. The arrangement of these components is crucial for the formation of nucleotides and the overall structure of DNA during processes like replication.

5 Must Know Facts For Your Next Test

1. The sugar in the backbone can be ribose in RNA or deoxyribose in DNA, contributing to differences in structure and function between these two nucleic acids.
2. The sugar-phosphate backbone is formed through phosphodiester bonds, which connect the 3' carbon atom of one sugar to the 5' phosphate group of the next nucleotide.
3. This backbone provides structural integrity to nucleic acids, ensuring that genetic information is accurately maintained and transmitted during cell division.
4. During DNA replication, the sugar-phosphate backbone is critical for creating complementary strands as DNA polymerase adds nucleotides to form new strands.
5. Any changes or damage to the sugar-phosphate backbone can lead to mutations or errors in DNA replication, affecting genetic stability.

Review Questions

• How does the structure of the sugar-phosphate backbone contribute to the overall stability of DNA?
  • The sugar-phosphate backbone plays a key role in providing structural stability to DNA due to its covalent phosphodiester bonds. These strong bonds link nucleotides together and protect the more chemically reactive nitrogenous bases that carry genetic information. Additionally, the helical structure formed by the twisting of the two strands further reinforces this stability, ensuring that DNA maintains its integrity during processes like replication.
• Discuss the significance of phosphodiester bonds in maintaining the integrity of the sugar-phosphate backbone during DNA replication.
  • Phosphodiester bonds are crucial for maintaining the integrity of the sugar-phosphate backbone as they connect individual nucleotides in a strand. During DNA replication, DNA polymerase synthesizes new strands by forming these bonds with incoming nucleotides. If these bonds are disrupted or incorrectly formed, it can lead to errors in replication, potentially resulting in mutations that affect gene expression and overall cellular function.
• Evaluate the impact of damage to the sugar-phosphate backbone on cellular processes and genetic stability.
  • Damage to the sugar-phosphate backbone can have serious consequences for cellular processes and genetic stability. When breaks occur in this backbone, it can hinder DNA replication and transcription, leading to incomplete or faulty copies of genetic information. Cells have repair mechanisms that attempt to fix such damage; however, persistent or severe damage may result in mutations that disrupt normal cellular functions or even lead to diseases such as cancer. This highlights the critical role that a stable sugar-phosphate backbone plays in maintaining overall genetic integrity.

Related terms

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

Double Helix: The shape of DNA, formed by two strands of nucleotides twisted around each other, held together by hydrogen bonds between nitrogenous bases.

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