DNA – NEET Notes

1. What is DNA?

• DNA stands for Deoxyribonucleic Acid.
• It is the carrier of genetic information in most organisms.
• Located in the nucleus and mitochondria (mtDNA).

2. Structure of DNA

• Double helix model (Watson & Crick, 1953).
• Made of nucleotides: nitrogen base + deoxyribose sugar + phosphate group.
• Base pairing: A–T (2 H-bonds), G–C (3 H-bonds).

3. Functions

• Storage and transmission of genetic information.
• Controls protein synthesis via transcription and translation.

4. DNA Replication

• Semi-conservative (Meselson & Stahl).
• Key enzymes: helicase, DNA polymerase, ligase.

5. DNA vs RNA

• DNA: Double-stranded, deoxyribose, bases A-T-G-C.
• RNA: Single-stranded, ribose, bases A-U-G-C.

Animated DNA Model