Let's dive deep into the world of proteins and their structures! 🚀

• All proteins start with at least one polypeptide (think of these as the "building blocks").
• Some proteins have more than one polypeptide, while others include non-polypeptide components.

When there's more than a single polypeptide, the 3D arrangement they form is called the quaternary structure.

Real-world Example: Think of it as assembling LEGO sets. Each piece (polypeptide) comes together to form the final structure (protein).

• Non-conjugated Proteins: Just the polypeptides!

  • e.g. Insulin: Has two polypeptides connected by disulfide bonds. (Check out Figure 8 on page 199!).
  • e.g. Collagen: Like a strong rope made from winding three polypeptides together. Perfect for giving your skin its strength! (See Figure 19 on page 207).

• Conjugated Proteins: Polypeptides PLUS non-polypeptide subunits. This mix boosts the protein's chemical and functional diversity.

  • e.g. Haemoglobin: Four polypeptides, each with an extra haem group. This group binds to oxygen, making haemoglobin the ultimate oxygen delivery service in our bodies!