Proteins

• What additional atom do proteins contain that carbohydrates and lipids do not?


  Nitrogen
• What are proteins made of?

  Proteins are polymers made of monomers called amino acids
• How many different amino acids are there?

  20
• What determines the shape of a protein?

  The specific sequence of amino acids in the chain
• What is a chain of amino acids called?

  A polypeptide
• What are the components of the basic structure of an amino acid?

  An amino group, a carboxyl group, a hydrogen atom, and an R-group
• What is the simplest amino acid?

  Glycine
• What is the difference between essential and non-essential amino acids?

  Essential amino acids cannot be synthesized by our bodies, while non-essential amino acids can be
• What is the process of forming a dipeptide from amino acids?

  • The amino group of one amino acid reacts with the carboxyl group of another
  • A condensation reaction occurs, eliminating water
  • A peptide bond is formed, resulting in a dipeptide
• What are the four levels of protein structure?

  1. Primary: Sequence of amino acids
  2. Secondary: Shape formed by hydrogen bonding (alpha helix or beta pleated sheet)
  3. Tertiary: Secondary structure held in a globular 3D shape
  4. Quaternary: Combination of two or more polypeptide chains
• What is the primary structure of a protein?

  The sequence of amino acids in a polypeptide chain
• What bonds maintain the tertiary structure of proteins?

  Disulphide, ionic, covalent, hydrophobic, and hydrogen bonds
• What is an example of a globular protein?

  Haemoglobin
• How do fibrous proteins differ from globular proteins?

  Fibrous proteins are structural and insoluble, while globular proteins are compact and soluble
• What are the characteristics of collagen?

  • Consists of three identical polypeptide chains
  • Provides structural support in tendons
  • Forms long, stable fibers
• What is the Biuret Test used for?

  Detecting the presence of peptide bonds
• What color change indicates a positive result in the Biuret Test?

  From blue to violet
• What does the intensity of the color in the Biuret Test indicate?

  The protein concentration or number of peptide bonds
• What must be described in any biochemical test result?

  The color change, not just the final color