Nucleotide

Definition

A nucleotide is the basic building block of nucleic acids, such as DNA and RNA, composed of three components: a nitrogenous base, a five-carbon sugar, and a phosphate group. Nucleotides link together through phosphodiester bonds to form the backbone of DNA and RNA strands, playing a critical role in storing and transmitting genetic information.

5 Must Know Facts For Your Next Test

1. Nucleotides are classified into two categories based on their nitrogenous bases: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil).
2. In DNA, nucleotides are arranged in a double helix structure with complementary base pairing: adenine pairs with thymine, and cytosine pairs with guanine.
3. The sequence of nucleotides in a DNA molecule encodes genetic information and determines the traits of an organism.
4. Nucleotides also play important roles beyond DNA and RNA, such as in energy transfer (e.g., ATP) and cell signaling (e.g., cyclic AMP).
5. During DNA replication, nucleotides are added to the growing strand by enzymes like DNA polymerase, ensuring accurate copying of genetic information.

Review Questions

• How do nucleotides contribute to the structure and function of DNA?
  • Nucleotides contribute to DNA's structure by linking together to form long chains through phosphodiester bonds, creating a sugar-phosphate backbone. Each nucleotide contains a nitrogenous base that pairs with complementary bases on the opposite strand, contributing to the double helix shape. The specific sequence of these nucleotides encodes genetic information crucial for cellular functions and inheritance.
• Discuss the significance of the different types of nitrogenous bases found in nucleotides.
  • The different nitrogenous bases in nucleotides—adenine, thymine, cytosine, guanine, and uracil—play crucial roles in determining genetic coding. Purines (adenine and guanine) are larger structures that pair with smaller pyrimidines (thymine, cytosine, or uracil), allowing for stable base pairing. The specific combinations of these bases form codons that dictate amino acid sequences in proteins, linking nucleotides directly to gene expression.
• Evaluate the importance of nucleotide structure in understanding genetic disorders and biotechnology applications.
  • Understanding nucleotide structure is essential for evaluating genetic disorders since mutations can arise from changes in nucleotide sequences, leading to malfunctioning proteins. In biotechnology, this knowledge is applied in techniques like CRISPR gene editing or PCR amplification, which rely on manipulating nucleotides for precise genetic modifications. By studying how nucleotide sequences impact health and disease, researchers can develop targeted therapies and diagnostic tools.

Related terms

nucleic acid: Molecules, including DNA and RNA, that are essential for all known forms of life and are composed of long chains of nucleotides.

nitrogenous base: A component of nucleotides that includes adenine (A), thymine (T), cytosine (C), guanine (G), and uracil (U) in RNA, responsible for base pairing and coding genetic information.

phosphodiester bond: The type of covalent bond that links the phosphate group of one nucleotide to the sugar of another, forming the sugar-phosphate backbone of nucleic acids.