Proteins

• What is the monomer of a protein?

  amino acid
• What elements make up an amino acid?

  carbon, hydrogen, oxygen, nitrogen
• What is the structure of amino acid?

  amine group and carboxyl group on either side of a central carbon atom, that is bonded to both a hydrogen and an R group
• What determines the type of amino acid?

  The R group (variable group)
• How are dipeptides formed?

  A condensation reaction between 2 amino acids where water is removed and a peptide bond is formed.

  - water is formed from the OH from the carboxyl group of one amino acid and the H from the amine group of the other

  - the peptide bond is formed between the C of the carboxyl group on one amino acid and the N from the amine group of the other
• What bond forms between 2 amino acids?

  peptide bond
• What is a polypeptide?

  chain of amino acids chemically joined together by peptide bonds
• What is meant by the primary structure of a protein?

  The specific sequence of amino acids in a polypeptide chain
• What is meant by the secondary structure of a protein?

  Localised areas of 3D folding where the polypeptide chain forms alpha helix and beta pleats
• What is meant by the tertiary structure of a protein?

  The folding of a polypeptide into its 3D structure
• What bonds are present in the primary structure?

  peptide bonds
• What bonds are present in the secondary structure?

  Hydrogen bonds
• What are the bonds present in the tertiary structure in order of strength (weakest to strongest)?

  Hydrophobic interactions, hydrogen bonds, ionic bonds, disulphide bridges
• What is a disulphide bridge?

  covalent bonds between sulphur containing R groups
• What will determine where bonds can form in the tertiary structure?

  the presence and location of specific amino acid R groups
• What is the quaternary structure of a protein?

  2 or more polypeptide chains held together by hydrogen bonds
• What are globular proteins?

  Water soluble proteins folded into a spherical tertiary or quaternary structure
• Do globular proteins have solubility?

  Yes - due to folding, the hydrophobic R groups are in the centre of the molecule and the hydrophilic R groups are on the outside
• 4 examples of globular proteins

  enzymes, plasma proteins, haemoglobin and antibodies
• What are fibrous proteins?

  Structural molecules with elongated, thread-like structures, often containing repeating amino acid sequences
• 4 examples of fibrous proteins

  keratin, collagen, actin, myosin
• What is keratin?

  Structural molecule found in hair and fingernails
• What do actin and myosin do?

  form structure of muscles
• What does collagen do?

  Fibrous protein found in bone, cartilage, ligaments, tendons and connective tissue. It makes up 30% of your body mass.