Lecture on DNA by Mr. Andersen

Introduction to DNA

• Foundation for understanding transcription, translation, mitosis, meiosis, and Mendelian genetics.
• DNA's simplicity compared to proteins.

Building Blocks of DNA

• Nucleotides: Building blocks of DNA and RNA.
  • Composed of three parts:
    1. Nitrogenous Base
       • Types in DNA: Guanine (G), Cytosine (C), Thymine (T), Adenine (A).
       • Purines: Guanine and Adenine (two carbon chains).
       • Pyrimidines: Cytosine and Thymine (simpler structure).
    2. Sugar
       • DNA contains deoxyribose sugar.
       • RNA contains ribose sugar.
    3. Phosphate Group
       • Known from ATP.

Structure of DNA

• Nucleotide Arrangement:
  • DNA has a 3' (3 prime) end and a 5' (5 prime) end.
  • Refers to the numbering of carbon atoms in the sugar.
  • Important in DNA replication.
• Antiparallel Nature:
  • DNA strands run in opposite directions.
  • Essential for DNA replication and functionality.

DNA Backbone and Base Pairing

• Backbone:
  • Consists of alternating deoxyribose and phosphate groups.
  • Identical on both strands.
• Base Pairing:
  • Purines pair with pyrimidines through hydrogen bonds.
  • Adenine pairs with Thymine; Guanine pairs with Cytosine.
  • Hydrogen bonds are weak, allowing DNA to unzip for replication or transcription.

Significance of DNA Structure

• Stability and Functionality:
  • Hydrogen bonds contribute to DNA's stability.
  • DNA's double helix provides a stable structure.
• Genetic Information Storage:
  • Sequence of bases codes for amino acids (triplet codons).
  • Enables transcription and translation processes.

Origin and Evolution

• DNA vs RNA:
  • RNA believed to be the initial genetic material.
  • DNA is considered an evolutionary upgrade due to its stability and error-checking capabilities.
  • Mutations can be corrected using the complementary DNA strand.

Conclusion

• DNA's simplicity lies in its role as an informational ladder instructing protein synthesis.
• Understanding DNA as a nucleotide sequence helps grasp its biological significance.