Nucleic acids

Nucleic Acids

Role and Structure of Nucleic Acids

  • Nucleic acids represent one of the four major types of macromolecules essential for life.
  • They are nature’s means of storing and transferring genetic information in a cell.
  • The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
  • Nucleic acids are composed of smaller units known as nucleotides, which consist of a sugar, a phosphate, and a nitrogen base.

DNA and Its Structure

  • In terms of structure, DNA usually takes the shape of a double helix, compared often to a twisted ladder.
  • The ‘rungs’ of this ladder are composed of nitrogenous bases: adenine (A), thymine (T), cytosine (C) and guanine (G).
  • Adenine pairs with thymine (A-T), and cytosine pairs with guanine (C-G) in what is known as complementary base pairing.
  • This structure is crucial for the replication of DNA during cell division.

RNA and Its Structures

  • RNA, unlike DNA, is typically single-stranded and can have a variety of shapes due to its flexibility.
  • It also has different nitrogenous bases: adenine (A), uracil (U), cytosine (C) and guanine (G).
  • RNA plays a key role in protein synthesis, acting as a messenger between DNA and the ribosomes where proteins are made.

Types of RNA

  • There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
  • Messenger RNA (mRNA) copies the genetic instructions from DNA in the cell’s nucleus and delivers them to ribosomes.
  • Ribosomal RNA (rRNA) combines with proteins to form ribosomes where proteins are synthesised.
  • Transfer RNA (tRNA) carries specific amino acids to the ribosome, matching them to the genetic code.

Replication, Transcription, and Translation

  • Replication is the process where DNA makes a copy of itself during cell division.
  • Transcription is the first step in protein synthesis. It’s where mRNA is produced by copying DNA’s genetic code.
  • Translation is the second step in protein synthesis, where mRNA’s code is read by the ribosomes and the specific protein is synthesized.

Importance of Nucleic Acids

  • Nucleic acids are vital for heredity, cell division, growth, and repair.
  • They ensure that genetic information is preserved and accurately passed from one generation to the next.