Proteins

• Which elements do all proteins contain?

  Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
• Besides the four main elements, some proteins also contain which element?

  Sulphur (S)
• What are proteins made up from?

  Amino acids
• What is the functional group in amino acids?

  The R group
• What amino acid results if the R group is hydrogen?

  Glycine
• How are individual amino acids joined together to form a polypeptide chain?

  By peptide bonds formed during condensation reactions
• What is formed during the condensation reaction that joins two amino acids?

  $H_2O$ (water)
• What are the four different protein structures?

  1. Primary structure
  2. Secondary structure
  3. Tertiary structure
  4. Quaternary structure
• What does the primary structure of a protein refer to?

  The order/sequence of amino acids in a polypeptide chain
• How does the amino acid sequence in primary structure affect proteins?

  Different amino acid sequences determine their properties and shape
• What do you need to know about the monomers of proteins?

  • The structure of amino acids
  • How their arrangement determines protein structure
  • How their arrangement determines protein function
• What are the different levels of organization in proteins?

  1. Primary structure
  2. Secondary structure
  3. Tertiary structure
  4. Quaternary structure
• What are the different bonds that hold protein structures together?

  • Hydrogen bonds
  • Ionic bonds
  • Disulphide bridges
  • Hydrophobic interactions
• How many different amino acids make up all our proteins?

  20
• What forms the secondary structure of proteins?

  • $\alpha-helix$
  • $\beta-pleated$ sheet
  • Held in place by hydrogen bonds
• How is tertiary structure formed in proteins?

  • Folding and twisting of the secondary structure
  • Forms a 3D globular shape
  • Held by different types of bonds: H-bonds, ionic bonds, disulphide bridges, hydrophobic interactions
• What are proteins with a tertiary structure called?

  Globular proteins
• Quaternary structure is made up from how many polypeptide chains?

  Two or more
• What type of non-protein part might a quaternary structure contain?

  A haem group
• What happens to a protein when it is denatured?

  Its shape changes and it prevents the protein from functioning properly
• Tertiary structure bonds

  • $H-bonds$ (hydrogen bonds)
  • Ionic bonds
  • Disulphide bridges
  • Hydrophobic interactions
• Structure held by H-bonds

  • Helical structure
  • Pleated sheet
• What is the name of the bond that links two amino acids together?

  Peptide bond
• What determines the structure and function of proteins?

  • Sequence of amino acids
  • Arrangement of monomers (amino acids)
  • Different levels of protein organization
  • Bonds holding protein structures together
• Name an amino acid involved in primary protein structure.

  Arginine (Arg)
• What determines the properties and shape of a protein?

  The amino acid sequence determines the interactions and folding of the polypeptide chain, which in turn determines the properties and shape of the protein.
• What have you likely learned about proteins in living organisms?

  Proteins are macromolecules with many different functions in living organisms, including acting as enzymes to control the rate of metabolism in cells and organisms.
• How is secondary structure held in place?

  By hydrogen bonds (H-bonds)
• How is quaternary structure formed in proteins?

  By two or more polypeptide chains joining together to make a molecule
• How many polypeptide chains does insulin contain?

  Two
• What group does haemoglobin contain that is essential for its function?

  A haem group containing iron
• What is the term for a protein that has lost its functional shape?

  Denatured
• What are the two types of secondary protein structure?

  • Helical structure
  • Pleated sheet
• How do temperature and pH changes affect proteins?

  Extreme changes in temperature and pH can break the bonds holding protein structures together, leading to denaturation and loss of function.
• What is a key function of enzymes in cells?

  They control the rate of metabolism in cells and organisms.
• What type of macromolecules are proteins?

  Proteins are macromolecules made up of monomers – amino acids.
• What is another name for an $\alpha-helix$ secondary structure in proteins?


  $\alpha-helix$
• What type of bonds hold the $\alpha-helix$ and $\beta-pleated$ sheet structures in proteins?


  Hydrogen bonds
• Name two types of proteins that have tertiary structure.

  • Enzymes
  • Hormones
• What term refers to the peptide backbone of a protein?

  Polypeptide backbone