DNA Structure and Importance

Introduction

• Rosalind Franklin's significant contribution to understanding DNA structure is often underappreciated.
• Understanding DNA structure has revolutionized science in the past 70 years.
  • Impact on species sequencing, human genome, medicine, and future therapies.

DNA Structure

• Double Helix
  • Two strands winding around each other.
• Components:
  • DNA bases: Cytosine, Guanine, Adenine, Thymine.
  • RNA bases: Cytosine, Guanine, Adenine, Uracil.
  • Bases in DNA are hydrogen-bonded.

Base Pairing

• DNA Base Pairing:
  • Adenine pairs with Thymine (2 hydrogen bonds).
  • Cytosine pairs with Guanine (3 hydrogen bonds, stronger interaction).
• Complementary Strands:
  • Predictable pairing (e.g., AGTC pairs with TCAG).

Directionality and Anti-parallel Nature

• Directionality:
  • DNA synthesized in 5' to 3' direction.
  • Strands are anti-parallel (one strand is 3' to 5', the other is 5' to 3').
• Importance in DNA replication
  • Anti-parallel nature is crucial for understanding DNA replication.

RNA Structure

• Single Strand:
  • Intramolecular hydrogen bonding occurs within the same molecule.
  • Important for RNA structure, e.g., transfer RNAs.

DNA Replication

• Fundamental Process:
  • Essential for gene inheritance across cells and generations.
• Carbon Orientation:
  • 5' carbon at the end of the strand binds to phosphate.
  • Alternating sugar-phosphate backbone (5' to 3').
• Complementary Strands:
  • Two DNA strands run in opposite directions.
  • Anti-parallel configuration aids understanding of replication mechanics.

Conclusion

• Understanding DNA structure elucidates DNA replication.
• Excitement upon initial discovery by Watson and Crick due to its explanatory power on DNA function.

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This overview provides essential insights into the structure and significance of DNA in biological processes and its foundational role in modern genetics.