Protein Structure and Function

• What is a protein?

  A macromolecule made up of amino acids that performs various functions in the body.
• What is the primary structure of a protein?

  The sequence of amino acids in a polypeptide chain.
• What determines the primary structure of a protein?

  The DNA of the cell.
• What does the primary structure of a protein determine?

  The proteins ultimate shape and function.
• What is a proteins shape specific to?

  Its function.
• What is the secondary structure of a protein?

  The polypeptide is twisted into a specific shape due to hydrogen bonding.
• What shapes are formed due to hydrogen bonding in the secondary structure?

  Alpha helix's, and beta pleated sheets.
• How are alpha helix's formed in the secondary structure of a protein?

  Hydrogen bonds form every fourth peptide bond.
• How are the beta pleated sheets formed in the secondary structure of a protein?

  The protein folds so that two parts of the polypeptide chain are parallel to each other and form hydrogen bonds.
• Where do the hydrogen bonds form between?

  The negatively charged oxygen on the carboxyl group and the positively charged hydrogen on the amine group.
• What kind of bond is a hydrogen bond in the secondary structure of a protein?

  A very weak bond.
• What is the tertiary structure of a protein?

  The structure is further folded into a unique 3D shape.
• What are the bonds hold the tertiary structure in place in order of strength?

  Disulphide bonds, Ionic bonds, and hydrogen bonds.
• What must there be for a disulphide bond to form?

  A sulphur in the R group of the amino acid (cysteine amino acid).
• Where do the bonds in the tertiary structure of a protein form between?

  The R groups of amino acids.
• What is a common tertiary structure protein?

  A globular protein.
• What is the tertiary structure important for?

  How a protein functions.
• What is the quaternary structure of a protein?

  More than one polypeptide chain linked together.
• What do quaternary structured proteins sometimes have accosted with them?

  Prosthetic (non-protein) groups.
• What is an example of a prosthetic group?

  A iron-containing haem group in haemoglobin.
• What can denature a protein?

  Too high temperatures or pH changes.
• What happens if a protein denatures?

  The bonds that hold the tertiary structure together break and the 3D shape is lost.
• What happens if one amino acid in the primary structure sequence is different?

  It would cause the tertiary bonds to form in different locations resulting in a different shape and function.
• What is each polypeptide chain in the quaternary structure referred to as?

  A subunit.