Complementary Base Pairing between A and T, C and G

DNA, or deoxyribonucleic acid, is a molecule that carries most of the genetic instructions used in the development, functioning and reproduction of all known living organisms and many viruses.
DNA includes four different types of bases, known as adenine (A), guanine (G), cytosine (C) and thymine (T).
Complementary base pairing is a rule stating that in DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).
The bases pair up through bonds called hydrogen bonds. A to T forms two hydrogen bonds while C to G forms three hydrogen bonds.
This pairing process is essential for DNA replication, enabling cells to copy their DNA precisely when they divide.
The structure that results from this complementary base pairing is a double helix, which is like a twisted ladder.
The ‘rungs’ of the ladder are the base pairs A-T and C-G, while the ‘sides’ of the ladder are made up of alternate sugar and phosphate molecules.
The reason why A pairs with T and C with G is due to their molecular structure. Adenine and thymine have a similar shape, allowing them to form two hydrogen bonds. Similarly, cytosine and guanine can form three hydrogen bonds.
The sequence of these bases determines the genetic information carried in the DNA molecule, which decodes into the proteins that make up our bodies and control our bodily functions.
Errors in base pairing can lead to mutations, which can potentially cause diseases or disorders. However, mutations can also lead to increased genetic diversity and evolution.
Knowledge of complementary base pairing is fundamental to the fields of genetics and molecular biology. For example, it is used in techniques such as DNA sequencing and polymerase chain reaction (PCR).
In sum, complementary base pairing is a key concept to understand DNA structure, genetics and the process of inheritance. It forms the basis of how information is stored and transferred from one generation to the next.