Complementary Base Pairing between A and T, C and G

Complementary Base Pairing between A and T, C and G

  • DNA, or deoxyribonucleic acid, is a molecule that carries genetic information used in the growth, development, functioning and reproduction of all living organisms.

  • This genetic information is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

  • These bases pair up with each other to form units called base pairs. Each base pairs up with just one other base; adenine with thymine, and cytosine with guanine. This is known as complementary base pairing.

  • Complementary base pairing is crucial in DNA replication. When a cell divides, a copy of the DNA is made. The original DNA strands serve as templates for the new strands, with A pairing with T and C pairing with G.

  • Adenine (A) always pairs with thymine (T) because they both form two hydrogen bonds, which is just enough to hold them together, but not too much to prevent accurate replication.

  • Cytosine (C) and guanine (G) pair together due to the three hydrogen bonds they form. This makes the bond stronger than an A-T bonding, but still allows for accurate replication.

  • During transcription, the process of producing mRNA from a DNA template, base pairing rules still apply but with a slight difference. Instead of T, uracil (U) in mRNA pairs with A in DNA.

  • Complementary base pairing ensures the genetic code is retained each time DNA is replicated, permitting accurate transmission of genetic information from one generation to the next.

  • Errors in this base pairing can result in mutations, which can lead to genetic disorders or diseases. However, some mutations can be beneficial, leading to variations which are the basis of evolution.

  • The sequence of these bases is extremely important and unique for each individual. It determines all genetic traits and characteristics, including eye colour, hair colour, height, and even susceptibility to certain diseases.

  • The complementary base pairing also allows DNA to be stored in a compact way, making it possible to fit a lot of information within the cell nucleus.