What three parts make up a single nucleotide

General
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what three parts make up a single nucleotide

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What three parts make up a single nucleotide?

Answer:
A single nucleotide, which is the basic building block of nucleic acids such as DNA and RNA, consists of three distinct parts:

  1. Nitrogenous Base
    • The nitrogenous base is a critical component of a nucleotide as it determines its identity and pairing properties. There are two main categories of nitrogenous bases:
      • Purines: These have a double-ring structure and include adenine (A) and guanine (G).
      • Pyrimidines: These have a single-ring structure and include cytosine (C), thymine (T), and uracil (U). Thymine is found only in DNA, while uracil is found only in RNA.

\text{Purines:} \quad \require{AMSsymbols} \text{\(A\) and \(G\)}

\text{Pyrimidines:} \quad \text{\(C\), \(T\) (DNA), and \(U\) (RNA)}

  1. Pentose Sugar

    • The type of pentose sugar differentiates between DNA and RNA.

      • Deoxyribose: This sugar lacks one oxygen atom and is found in DNA.
      • Ribose: This sugar has one more oxygen atom compared to deoxyribose and is found in RNA.
      \text{DNA Sugar:} \quad C_5H_{10}O_4 \quad (\text{Deoxyribose})
      \text{RNA Sugar:} \quad C_5H_{10}O_5 \quad (\text{Ribose})

  2. Phosphate Group

    • The phosphate group consists of one phosphorus atom bonded to four oxygen atoms and is responsible for the acidic properties and the negative charge of nucleic acids. It links the sugar molecules of adjacent nucleotides together through phosphodiester bonds, forming the backbone of the DNA or RNA strand.

      \text{Phosphate Group:} \quad PO_4^{3-}

Structure and Bonding

  • Nucleotide Formation: The nitrogenous base is attached to the pentose sugar at the 1’ carbon atom (carbon-1 of the sugar), forming a nucleoside. When one or more phosphate groups are attached to the 5’ carbon atom of the sugar, a nucleotide is formed.
  • Phosphodiester Bonds: Nucleotides in a DNA or RNA strand are connected by phosphodiester bonds between the 3’ hydroxyl group (OH) of one nucleotide’s sugar and the 5’ phosphate group of the next nucleotide’s sugar.

Summary

To encapsulate, a nucleotide is composed of:

  1. A nitrogenous base (A, T, G, C in DNA; A, U, G, C in RNA)
  2. A pentose sugar (deoxyribose in DNA, ribose in RNA)
  3. A phosphate group

Understanding these components is essential for grasping how nucleic acids store and transmit genetic information.