Nucleotide

Definition

A nucleotide is the basic building block of nucleic acids, such as DNA and RNA, consisting of a nitrogenous base, a five-carbon sugar, and one or more phosphate groups. Nucleotides play a crucial role in storing and transferring genetic information, forming the structure of DNA, and facilitating DNA replication.

5 Must Know Facts For Your Next Test

1. Nucleotides can be classified into two categories: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil).
2. In DNA, nucleotides pair specifically: adenine with thymine and guanine with cytosine, forming base pairs that are essential for the double helix structure.
3. Each nucleotide contains a unique nitrogenous base which determines the genetic code carried by the DNA or RNA molecule.
4. During DNA replication, nucleotides are added to the growing strand by complementary base pairing, ensuring accurate copying of genetic information.
5. Nucleotides also serve other functions in cellular metabolism, such as ATP (adenosine triphosphate), which is a key energy carrier in cells.

Review Questions

• How do the components of a nucleotide contribute to its role in forming DNA?
  • A nucleotide consists of a nitrogenous base, a five-carbon sugar (deoxyribose in DNA), and one or more phosphate groups. The nitrogenous base pairs with a complementary base on the opposite DNA strand, while the sugar-phosphate backbone provides structural integrity. This combination allows nucleotides to link together into long chains, forming the double helix structure of DNA that is essential for storing genetic information.
• Discuss the importance of specific base pairing among nucleotides during DNA replication.
  • Specific base pairing during DNA replication ensures that each new strand formed is an exact copy of the original strand. Adenine pairs with thymine and guanine pairs with cytosine due to their complementary shapes and hydrogen bonding properties. This specificity allows for accurate copying of genetic information, which is vital for cell division and maintaining genetic fidelity across generations.
• Evaluate how the structure of nucleotides influences their function in both DNA and RNA molecules.
  • The structure of nucleotides directly influences their function in both DNA and RNA. In DNA, the double-helix structure formed by nucleotides is stabilized by hydrogen bonds between complementary bases. This structural integrity allows for effective storage of genetic information. In RNA, nucleotides can form various structures due to their single-stranded nature and presence of uracil instead of thymine. This flexibility enables RNA to play diverse roles in protein synthesis and regulation of gene expression, highlighting how structural differences lead to functional diversity.

Related terms

DNA: Deoxyribonucleic acid, the molecule that carries genetic instructions in living organisms, composed of two strands forming a double helix.

RNA: Ribonucleic acid, a nucleic acid involved in protein synthesis and gene expression, usually single-stranded and contains ribose sugar.

phosphodiester bond: The chemical bond that links nucleotides together in a strand of DNA or RNA, formed between the phosphate group of one nucleotide and the sugar of another.