The smartest molecule in existence!
DNA molecule performs so many intelligent functions so effortlessly.
"To understand the process of DNA replication, we must first be familiar with the structure of DNA. So, lets have an overview of DNA structure and its functions".
DNA is the molecule that passes on our genetic information. The publication of its structure on the 25th of April 1953 was vital to understanding how it achieves this task with such startling efficiency.
Resembling a twisted ladder or a zipper, DNA is a double helix formed with nucleotides (structural units of DNA containing a base, a sugar, and one or more phosphates), a phosphate and sugar backbone, and nitrogenous bases. There are four bases, and each one will only bond with its complement. Adenine will only bond with Thymine, and Cytosine with only Guanine. The double helix is anti – parallel, meaning each strand runs in a different direction.
DNA's structure is a bit like a twisted ladder:
The twisted 'rails' are made of sugar–phosphate, which give DNA its shape and protect the information carrying 'rungs' (A level in a hierarchical structure) inside. Each sugar–phosphate unit is joined to the next by a tough covalent bond, which needs a lot of energy to break. In between the 'rails', weaker hydrogen bonds link the two halves of the rungs together. Individually each hydrogen bond is weak – but there are thousands of hydrogen bonds within a single DNA molecule, so the combined effect is an extremely powerful stabilizing force.
The DNA duplex:
The sugar–phosphate backbone is illustrated in red, as the sides of the ladder. The base pairs are represented as rungs of the ladder. Adenine (A) is complementary to thymine (T), and guanine (G) is complementary to cytosine (C). The two strands of DNA are antiparallel. Most double–stranded DNA is found in a right–handed helix (shown on the right). One full turn of a typical DNA helix is 3.4 nm, encompassing approximately 10 base pairs per turn. The width of the helix is approximately 2 nm.