Comprehensive Notes on Proteins and Nucleic Acids

Review: Nucleic Acids (from AP Classroom Questions)

• Previous Homework Recall: Discussion started with a review of nucleic acids, specifically focusing on questions from AP Classroom that were not covered in the previous short block.

• Key Terms: Pyrimidines and purines are different types of nitrogenous bases found in nucleic acids.

  • Pyrimidines: Include Cytosine (C), Thymine (T), and Uracil (U). They are characterized by having one ring structure.

  • Purines: Include Adenine (A) and Guanine (G). They are characterized by having two rings structure.

• Complementary Base Pairing in DNA: In a double-stranded DNA, specific bases always pair up:

  • Adenine (A) always pairs with Thymine (T).

  • Guanine (G) always pairs with Cytosine (C).

• Reason for Specific Pairing: This pairing is crucial for maintaining the consistent width of the DNA double helix.

  • One purine (two rings) always pairs with one pyrimidine (one ring). For example, A (two rings) pairs with T (one ring), and G (two rings) pairs with C (one ring).

  • This arrangement ensures perfect spacing across the DNA strand, as a two-ring base always pairs with a one-ring base, resulting in a uniform 3 ring width (if considering the covalent bonds that connect them indirectly across the helix) between the two strands at each base pair.

Introduction to Proteins

• Monomer and Polymer of Proteins:

  • Monomer: Amino acid.

  • Polymer: Polypeptide (a string of amino acids linked together).

• Protein vs. Polypeptide Distinction:

  • A single polypeptide chain can function as a protein.

  • However, many proteins are composed of multiple polypeptide chains (subunits).

  • Therefore,