Amino acids are linked by ___ ___.

### Peptide bonds

## Step1: Understanding the Structure of Amino Acids### Amino acids are organic compounds composed of nitrogen, carbon, hydrogen, and oxygen, along with a variable side chain group. The basic structure of an amino acid includes a central carbon atom, also known as the alpha carbon, bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R group) that differentiates one amino acid from another.## Step2: Formation of Peptide Bonds### Peptide bonds are formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid. This reaction is a condensation reaction, meaning that it releases a molecule of water (H2O). The resulting covalent bond between the carbon atom of the carboxyl group and the nitrogen atom of the amino group is called a peptide bond.## Step3: Linking of Amino Acids### The linkage of amino acids through peptide bonds forms a chain, which is the primary structure of proteins. This process repeats, with each new peptide bond forming between the carbonyl carbon of one amino acid and the amino nitrogen of the next, resulting in a long chain of amino acids linked by peptide bonds.