B1.2 Lecture on Proteins

Introduction to Proteins

• Proteins are long chains of monomers called amino acids.
• There are 20 different types of amino acids.

Structure of Amino Acids

• Amino acids share a general structure:
  • Central carbon atom.
  • Carboxy group (double-bonded oxygen and hydroxy group).
  • Amine group (nitrogen and two hydrogens).
  • Hydrogen atom.
  • Functional group (R group) which varies among amino acids.
• All amino acids are three-dimensional.

Formation of Polypeptides

• Amino acids form polypeptides, which fold into proteins.
• Dipeptide: Two amino acids bonded together.
• Polypeptide: Many amino acids bonded together.
• Connection through condensation reactions (removal of water).
• Formation of special bond called peptide bond.

Diversity of Amino Acids

• All 20 amino acids have the same basic structure; differ in R group.
• Plants can manufacture all 20 amino acids.
• Humans can synthesize only 9; need to consume remaining 11 (essential amino acids).

Importance of Amino Acids in Diet

• Essential amino acids must be consumed through diet.
• Variety in protein sources is vital, especially for vegan or plant-based diets.

Role of DNA and RNA

• DNA contains codes for polypeptides; RNA acts as a temporary messenger.
• Proteome: Set of proteins an organism can produce.
• Infinite possibilities for different polypeptides.

Examples of Proteins

• Proteins like insulin, Amal, Titan have different structures and functions.

Protein Synthesis

• Polypeptides become proteins when folded into specific shapes.
• Protein function is specific to its shape.

Denaturation of Proteins

• Denaturation is a permanent change in protein structure and function.
• Causes:
  1. Heat: Increases reaction rate up to a point, then causes denaturation.
  2. pH: Each protein has an optimal pH for function; deviation from this pH leads to denaturation.
• Denaturation disrupts bonds between amino acids, altering protein shape.

Conclusion

• Protein function is highly dependent on its form.
• Changes in form can drastically affect the protein's functionality.