DNA

DNA (deoxyribonucleic acid) is the molecule that stores genetic information. It consists of two strands coiled together to form a double helix; each strand contains chemicals called bases, and bonds between pairs of bases hold the two strands together ¹.

Base Pairing

The bases always pair up in the same way — A with T and C with G — so one strand carries the information needed to reconstruct the other.

  strand 1  ─ A ─ T ─ C ─ G ─
              │   │   │   │        double helix
  strand 2  ─ T ─ A ─ G ─ C ─

Where DNA Is Found

• In plant and animal cells, chromosomes are made of DNA, which contains genetic information in the form of genes; a gene is a length of DNA that codes for a protein ¹.
• In bacterial cells, DNA is a single circular molecule, together with small circles called plasmids.
• The sequence of bases in a gene determines the sequence of amino acids used to make a specific protein, so DNA controls cell function through the proteins and enzymes it specifies.

Related

• Nucleus - Structure holding the chromosomes.
• Nuclear Envelope - Membrane separating DNA from the cytoplasm.
• Ribosome - Where the protein coded by a gene is assembled.
• Cell - Structural unit containing the genetic material.
• Reproduction - DNA is passed to offspring via gametes.
• Biology - Cambridge IGCSE life-science area.