proteins

• what are polymers?

  long chains of repeating units made up from smaller simpler monomers
• how many amino acids does the body use?

  20
• what is the term for when an amino acid joins to another amino acid?

  • condensation reaction
  • water molecule is released
  • peptide bond is formed
  • resulting molecule is a dipeptide
• state the term for a monomer of a protein, a di-monomer of a protein and a polymer of a protein

  • amino acid- monomer
  • dipeptide- di-monomer
  • polypeptide- polymer
• how do proteins produce different shapes?

  • presence of different combinations of AAs result in different shapes being produced
  • vital as proteins have many different functions within organisms
• state and describe each level of protein structure

  • primary- sequence of AA. This influences how the protein will fold to give the final shape and determines its function. Bonds involved- peptide bonds
  • secondary- O, H and N atoms interact. Formation of an alpha helix or a beta pleated sheet. Bonds involved- peptide and hydrogen bonds forming within the AA chain
  • tertiary- folding of a protein into its final shape. Folding brings R groups together, close enough to interact, so further folding occurs. Bonding between R groups- hydrogen bonds, disulphide bridges (between R groups containing sulphur atoms), ionic bonds, hydrophobic and hydrophilic interactions (between polar and non-polar R groups)
  • quaternary- same interactions as with tertiary, occurring between two different polypeptide chains

  
• what are the two main protein groups?

  • globular
  • fibrous
• state examples of globular proteins

  • insulin
  • conjugated proteins- globular proteins that contain non-protein component called prosthetic group- haemoglobin, haem group containing iron is prosthetic
  • catalase
• describe the properties of globular proteins

  • compact
  • water soluble
  • spherical in shape roughly
  • fold so that hydrophobic R groups are folded inward and kept away from aqueous envviros, so the proteins an be soluble in water
• why is insulin soluble and have a specific shape

  • needs to be transported in blood plasma
  • needs to bind to specific receptors on cell membranes
• true or false? in lipoproteins or glycoproteins, lipids and carbohydrates bind to proteins, and they are regarded as prosthetic groups

  TRUE- as they are non-protein components
• true or false? catalase contains a haem group

  TRUE
• what level of protein structure is haemoglobin at? what type of protein is it and what is its structure?

  • quaternary
  • 4 polypeptide chains
  • 2 alpha and 2 beta subunits
  • each subunit contains haem group
• what level of protein structure is catalase at? what type of protein is it and what is its structure?


  • globular
  • quaternary
  • 4 haem prosthetic groups
  • iron in haem groups
  • interacts with hydrogen peroxide to break it down
• state the different types of fibrous proteins. Where are they found?

  • keratin- hair, skin, nails, inflexible
  • elastin- elastic fibres in blood vessel walls and alveoli of lungs, flexible
  • collagen- skin, tendons, ligaments and nervous system, flexible, 3 polypeptides
• state the properties of fibrous proteins

  • long and insoluble
  • due to a large proportion of hydrophobic R groups
  • not folded into complex three dimensional shapes like globular proteins