Nucleic acids

• Nucleic acids are large, complex biomolecules essential for storing genetic information, synthesizing proteins, and regulating gene expression.
• They are composed of nucleotides, which consist of a pentose sugar, a phosphate group, and a nitrogenous base.
• These molecules primarily contain carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P).

Classification of Nucleic Acids

• Nucleic acids are classified into two main types, each with distinct structures and functions:
• Nucleic acids are classified into two major types, each with distinct structures and functions:

1. Deoxyribonucleic Acid (DNA)

• • Structure:

    • DNA is a double-stranded molecule with two complementary chains forming a double helix.
    • Composed of deoxyribose sugar and four nitrogenous bases:
      • Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

  • Function:

    • Stores genetic information for protein synthesis, cellular functions, and inheritance.

  • Examples:

    • Found in the nucleus, mitochondria, and chloroplasts of cells.

2. Ribonucleic Acid (RNA)

• • Structure:

    • RNA is typically single-stranded and exists in multiple forms.
    • Contains ribose sugar and four nitrogenous bases:
      • Adenine (A), Uracil (U), Cytosine (C), Guanine (G) (Uracil replaces Thymine in RNA).

  • Function:

    • Plays a critical role in protein synthesis and gene regulation.

  • Types of RNA and Their Roles:

    • mRNA (Messenger RNA): Transcribes genetic information from DNA and transports it to ribosomes.
    • tRNA (Transfer RNA): Brings specific amino acids to the ribosome during protein synthesis.
    • rRNA (Ribosomal RNA): Forms the structural and functional core of ribosomes, catalyzing protein synthesis.

Table displaying the differences between the classifications of nucleic acids

Classification	Structure	Sugar	Bases	Function	Examples
DNA	Double-stranded, double helix	Deoxyribose	A, T, C, G	Genetic information storage, heredity, guiding protein synthesis	Genomic DNA, mitochondrial DNA
RNA	Usually single-stranded, various structures	Ribose	A, U, C, G	Protein synthesis, gene regulation, catalytic activities, genetic information transfer	mRNA, tRNA, rRNA, miRNA, lncRNA

Properties of Nucleic Acids

1. Polarity:

   • Nucleic acids have a directional structure with a 5′ phosphate group at one end and a 3′ hydroxyl group at the other, determining how nucleotides are added during synthesis.

2. Base Pairing:

   • DNA bases form specific hydrogen bonds:
     • A pairs with T (in DNA) or U (in RNA).
     • C pairs with G in both DNA and RNA.
   • This complementary pairing ensures accurate replication and transcription.

3. Stability:

   • DNA’s double-stranded structure and deoxyribose sugar make it more chemically stable than RNA, which is more prone to degradation due to its single-stranded nature.

Functions of Nucleic Acids

1. Genetic Information Storage:

   • DNA stores hereditary information essential for development, function, and reproduction.

2. Protein Synthesis:

   • mRNA carries genetic instructions from DNA to ribosomes.
   • tRNA delivers amino acids for protein assembly.
   • rRNA facilitates the formation of proteins.

3. Gene Regulation:

   • Non-coding RNAs (e.g., microRNAs, long non-coding RNAs) regulate gene expression at transcriptional and translational

Chemical Nature and Biological Role

1. Chemical Nature of Nucleic acids:

   • DNA and RNA consist of nucleotide chains, with structural differences:
     • DNA: Contains deoxyribose sugar, uses Thymine (T) instead of Uracil (U).
     • RNA: Contains ribose sugar, replaces Thymine with Uracil.

2. Biological Role of Nucleic acids:

   • Genetic Information Storage:
     • DNA encodes genetic instructions for protein synthesis and cellular function.
   • Transcription and Translation:
     • DNA is transcribed into RNA, which is translated into proteins—the functional molecules of the cell.
   • Gene Regulation:
     • RNA molecules help control gene expression, determining which proteins are produced and when.

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