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Amino acids are the building blocks of proteins. They play a crucial role in various biological processes within our bodies. Think of them as the "letters" that combine in different ways to form "words," which represent proteins. There are 20 different amino acids that commonly appear in proteins. Each amino acid has a unique side chain that determines its properties and role in protein structure.
Amino acids are organic molecules composed of:

• An amino group (-NH₂)
• A carboxyl group (-COOH)
• A distinctive side chain (R group)

These groups are attached to a central carbon atom, known as the alpha carbon. The unique sequence of amino acids in a protein determines its structure and function. In the exercise, we discussed glycine (Gly) and valine (Val), two of the common amino acids found in proteins. Glycine is the simplest amino acid with a single hydrogen atom as its side chain, while valine has a branched-chain structure, giving it different chemical properties.

Dipeptides are a specific type of peptide consisting of two amino acids linked by a single peptide bond. When two amino acids join through their amino and carboxyl groups, they form dipeptides. This connection results from a process known as dehydration synthesis, which removes a water molecule.
The formation of a peptide bond involves:

• The amino group (-NH₂) of one amino acid
• The carboxyl group (-COOH) of the adjacent amino acid
• A water molecule that is released during the reaction

In the example given, Gly-Val and Val-Gly are distinct dipeptides because of the order of the amino acids. The N-terminus is the start of the peptide chain, and the C-terminus is the end. Gly-Val has glycine at the N-terminus and valine at the C-terminus, and vice versa for Val-Gly. This order affects the properties and function of the dipeptide.

Biochemical reactions are processes that occur within living organisms to sustain life. These reactions often involve the making and breaking of chemical bonds. In the context of peptide bond formation, a biochemical reaction known as condensation or dehydration synthesis is key.
Here's how the reaction unfolds:

• The carboxyl group of one amino acid joins with the amino group of another.
• This process eliminates a water molecule (H₂O).
• The result is the formation of a peptide bond, linking the two amino acids.

This reaction is fundamental in forming peptides and ultimately proteins. Understanding these reactions is essential in biochemistry, as they define how various biological molecules interact and function. The specificity of these reactions means that even a slight change in the sequence of amino acids can lead to different biological outcomes, as seen with Gly-Val and Val-Gly.