Molecular Structure of DNA

DNA, or deoxyribonucleic acid, is a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. Its molecular structure was famously elucidated by James Watson and Francis Crick in 1953, based on data collected by Rosalind Franklin and Maurice Wilkins.

 

The molecular structure of DNA is often depicted as a double helix. Here's a brief breakdown of its components and structure:

1. Nucleotides: The basic building blocks of DNA. Each nucleotide consists of three components:

   • A phosphate group
   • A sugar molecule (deoxyribose)
   • One of four nitrogenous bases: adenine (A), cytosine (C), guanine (G), or thymine (T).

2. Base Pairing: Adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). This is due to hydrogen bonding between specific pairs of nitrogenous bases. This complementary base pairing ensures the stability of the DNA molecule.

3. Double Helix Structure: The two strands of DNA twist around each other to form a double helix. The sugar-phosphate backbones of the two strands are on the outside, while the nitrogenous bases are paired and located on the inside.

4. Antiparallel Orientation: The two strands of DNA run in opposite directions, with one running in the 5' to 3' direction and the other running in the 3' to 5' direction. This arrangement is termed antiparallel.

5. Major and Minor Grooves: The double helix structure of DNA forms grooves, termed major and minor grooves, where the nitrogenous bases are accessible for interactions with other molecules such as proteins.

 

Overall, the molecular structure of DNA is elegantly designed to encode genetic information in its sequence of nucleotides and to replicate faithfully during cell division.

 

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