Proteins

• What are the building blocks of proteins?

  Amino acids
• What is the general structure of an amino acid?

  It has a carbonyl group, amino group, and R group
• What is the exception to the amino acid structure rule?

  Glycine
• How are amino acids linked together?

  By condensation reactions
• What are the bonds formed between amino acids called?

  Peptide bonds
• What happens during hydrolysis of dipeptides?

  Dipeptides are broken down into amino acids
• What are the four levels of protein structure?

  • Primary structure: Sequence of amino acids
  • Secondary structure: Alpha-helix or beta-pleated sheet
  • Tertiary structure: 3D shape from further folding
  • Quaternary structure: Assembly of multiple polypeptide chains
• What is the primary structure of a protein?

  The sequence of amino acids in the chain
• What forms the secondary structure of a protein?

  Hydrogen bonds between amino acids
• What additional bonds form in the tertiary structure of proteins?

  Hydrogen bonds, ionic bonds, and disulfide bridges
• What is the quaternary structure of a protein?

  The assembly of multiple polypeptide chains
• What is an example of a protein with quaternary structure?

  Hemoglobin
• What are the functions of structural proteins?

  • Transport or store substances
  • Provide structural support
  • Example: Collagen for strength
• What is the biuret test used for?

  To test for the presence of protein
• What is added to the biuret test solution to make it alkaline?

  Sodium hydroxide
• What indicates a positive result in the biuret test?

  A purple color forms in the solution
• What does a blue solution indicate in the biuret test?

  No protein is present
• Why was the cow's milk test result marked as void?

  Its pH was below 7
• What mistake might the scientist have made during the biuret test?

  Not ensuring the solution was alkaline
• What are the monomers of proteins?

  Amino acids
• What is a polypeptide?

  A chain of amino acids linked together
• What sort of reaction links amino acids together?

  Condensation reaction
• What is the name of the bond that forms between amino acids?

  Peptide bond
• Name three bonds that may form in the tertiary structure of a protein.

  Hydrogen bonds, ionic bonds, disulfide bridges
• How does the shape of structural proteins relate to their function?

  They provide strength and support
• What is the first step in the biuret test?

  Add sodium hydroxide to make it alkaline
• What is added after sodium hydroxide in the biuret test?

  Add copper(II) sulfate solution
• What does a positive biuret test look like?

  The solution turns purple
• What does a negative biuret test indicate?

  The solution stays blue
• What is the significance of assessing hazards before tests?

  To ensure safety during experiments
• Why should safety goggles be worn during the biuret test?

  Because sodium hydroxide is an irritant