Proteins

• What monomers make up proteins?

  amino acids
• What are two amino acids called?

  dipeptide
• What are 3 or more amino acids called?

  Polypeptide
• What are proteins? Two or more polypeptides
• What is the structure of an amino acid?

  Amine group (NH2) variable group (CHR) carboxyl group (COOH)Molecular formula NH2CHRCOOH
• How are polypeptides made?

  Condensation reactions between amino acids to form peptide bonds.
• What is the primary structure of a protein?

  sequence of amino acids in a polypeptide chain.
• What is the secondary structure of a protein?

  Either forms an alpha helix or beta pleated sheet. Hydrogen bonds form between the amino acids.
• What is the tertiary structure of a protein?

  folding of a polypeptide chain due to interactions between side chains of amino acids. Hydrogen bonds, ionic bonds between the negative amine and positive carboxyl group, and disulphide bridge if sulphur is present in both R groups form.
• What is the quaternary structure of a protein?

  when 2 or more polypeptide chains join to form a 3D protein. It may include a non-protein group that aids function e.g. haemoglobin contains a heme group to add iron.
• What is the structural aid in the function of an enzyme?

  Spherical due to tight folding and soluble as they often have roles in metabolism.
• What is the structural aid to the function of antibodies?

  2 light and 2 heavy polypeptide chain bonded together. Used in the immune system and found in the blood.
• What is the structural aid to the function of transport proteins?

  Hydrophilic head and hydrophobic tail allow it to fold up and create a channel so molecules and ions can be transported across membranes.
• What is the structural aid to the function of structural proteins?

  Long parallel polypeptide chains with cross links between them to increase tensile strength.
• What is the test for proteins?

  Biuret test
• What is the method for the biuret test

  add sodium hydroxide and then add copper ii sulphate.
• What is the result of the bieuret test?

  No protein - stays blue Protein - turns violet.
• What are the two types of 3D proteins?

  globular and fibrous
• what are globular proteins?

  globular proteins have a round, spherical formation. This is because the hydrophobic parts of the protein fold inwards while the hydrophilic parts become arranged around the external surface.
• are globular proteins water soluble?

  yes, as the hydrophilic components of the protein are on the external surface
• what is the function of globular proteins?

  enzymes, transport proteins, messenger proteins
• give an example of a globular protein?

  haemoglobin
• what are fibrous proteins?

  Fibrous proteins are long chains. They are made up of repeated amino acid sequences that form long polypeptide chains. These chains twist together to form fibrous proteins.
• are fibrous proteins water soluble?

  no, as the hydrophobic component of the protein are not folded away and are present on the external surface.
• what is the function of fibrous proteins?

  structural proteins
• give an example of a fibrous proteins?


  collagen
• Two similarities between all peptides

  All contain C,N,H,O

  More than 2 R groups
• how do all peptides differ?

  different R groups
• Two proteins have the same number and type of amino acids but different tertiary structures.

  Explain why.

  sequence of AA differs, so bonds form in different places