## What Is a Peptide Chain?
A peptide chain is a string of amino acids linked together by special chemical bonds called peptide bonds. To really understand what this means, let’s break it down piece by piece, starting with the building blocks and moving up to how these chains form the basis of life itself.
### The Building Blocks: Amino Acids
Amino acids are small molecules that serve as the basic units for building proteins and peptides. Think of them like individual Lego bricks. Each amino acid has a central carbon atom, called the alpha carbon, which is connected to four different groups: an amino group (—NH₂), a carboxyl group (—COOH), a hydrogen atom (—H), and a side chain (often called the R group). The side chain is what makes each amino acid unique—there are 20 standard types in humans, each with its own distinct R group.
When you look at an amino acid, you can picture it as having a “head” (the amino group), a “tail” (the carboxyl group), and a “tag” hanging off the side (the R group). This structure allows amino acids to link together in long chains.
### How Amino Acids Link Together: The Peptide Bond
When two amino acids come together, they can form a bond between them. This happens when the carboxyl group of one amino acid reacts with the amino group of another. In this reaction, they lose a molecule of water—this is called a condensation reaction. The new bond that forms between them is known as
