23.2. Amino Acids and Proteins
By Abbie

Amino Acids - The Basics
  • Amino Acids are the basic building blocks of proteins.
  • By definition, Amino Acids are organic molecules that contain two functional groups: A basic NH2 amino group and an acidic (-COOH) carboxylic acid group.
The Structure of Amino Acids
There are 20 amino acids that all have the same basic structure.


Amino Acid Reactions
Amino Acids react with each other.
Basic Amino Group (of one amino acid) + Acidic Carboxylic Acid Group (of another amino acid) ----> peptides + water
peptide bond - a bond formed as a result of the amino acid reaction
dipeptide - the product of the reaction because it is made up of two amino acid units.
polypeptides - longer chains
proteins - chains of 50 or more amino acids.
proteases - enzymes that break peptide bonds.

  • Amino Acids are extremely important to a protein chain because the difference of only one can cause a big change in a protein's activity in a cell.
  • Amino acid side chains also determine the shape and the structure of proteins.
  • A primary structure is the sequence of the amino acids in a polypeptide chain or protein.
  • A seconday structure describes how the chain is coiled or arranged.
  • Tertiary structures are the three-dimensional shapes of protein.
  • Quaternary structures are the four different polypeptides of hemoglobin.