What is the structure of DNA?

Structure of DNA (Deoxyribonucleic Acid)

1. Double Helix
   • DNA is shaped like a twisted ladder called a double helix.
   • The two strands twist around each other.
2. Backbone
   • The sides of the “ladder” are made of sugar (deoxyribose) + phosphate groups.
   • These form the sugar-phosphate backbone.
3. Nitrogenous Bases
   • The “rungs” of the ladder are paired nitrogenous bases:
     • Adenine (A) ↔ Thymine (T)
     • Guanine (G) ↔ Cytosine (C)
   • Base pairs are held together by hydrogen bonds.
     • A–T: 2 hydrogen bonds
     • G–C: 3 hydrogen bonds
4. Antiparallel Strands
   • The two DNA strands run in opposite directions (one 5′ → 3′, the other 3′ → 5′).
5. Major and Minor Grooves
   • Twisting creates grooves where proteins can bind for replication and transcription.

Functions of DNA Structure

• Stores genetic information in the sequence of bases.
• Allows replication because strands can separate and copy themselves.
• Facilitates transcription into RNA for protein synthesis.

In short:

DNA is a double-stranded helix made of a sugar-phosphate backbone and paired nitrogenous bases (A–T, G–C), which stores and transmits genetic information.