Protein

• What are proteins also referred to as?

  Peptides
• What is formed when two amino acids react together?

  A dipeptide and water
• What type of bond is formed between two amino acids?

  A peptide bond
• What is a protein composed of?

  A protein is a polypeptide.
• How are amino acids joined together in proteins?

  Amino acids are joined by condensation.
• How many types of amino acids are there?

  There are 20 types of amino acids.
• What does the primary structure of a protein refer to?

  The primary structure refers to how many amino acids are present and in what order they are arranged.
• What is the secondary structure of a protein?

  The secondary structure refers to the coils and folds of the polypeptide chain.
• What are the two types of secondary structures in proteins?

  The two types of secondary structures are alpha helixes and beta pleats.
• What is the tertiary structure of a protein?

  The tertiary structure is the 3D structure formed when the secondary structure twists and folds.
• What types of bonds are involved in the tertiary structure of proteins?

  The bonds involved are hydrogen bonds, ionic bonds, and disulphide bridges.
• What are the two examples of tertiary proteins and their characteristics?

  • Fibrous: long and thin, like keratin
  • Globular: spherical, like enzymes
• What is the difference between soluble and insoluble proteins?

  Insoluble proteins do not dissolve in water, while soluble proteins do.
• What is the quaternary structure of a protein?

  The quaternary structure is formed when two or more polypeptides are folded together.
• Give an example of a protein with a quaternary structure.

  Hemoglobin is an example of a protein with a quaternary structure.
• How do you test for protein using the Biuret test?

  Add a few drops of sodium hydroxide and then a few drops of dilute copper sulfate.
• What color change indicates a positive result in the Biuret test for protein?

  The solution turns purple.