Proteins

• What proteins are made in the body?


  ○Amino acids

  ○enzyme

  ○antibodies

  ○hormones

  ○haemoglobin

  ○muscle

  ○keratin

  ○collegen
• What components make up a protein?


  ○amino acid group

  ○carboxylic acid group

  ○R group

  ○H group

  ○a central carbon
• Biuret's reagent


  (Dilute copper sulphate + sodium hydroxide)

  If amino acids are present purple precipitate forms

  Turns darker purple depending on how much protein is present
• How does heat denature enzymes?

  Heat energy increases the kinetic energy, making the molecule vibrate more.

  These vibrations are strong enough to break the intermolecular bonding.

  Therefore denaturing the enzyme
• Enzymes

  Amylase
• Transport


  Haemoglobin
• Movement


  Actin and Myosin
• Cell recognition

  Antigens
• Channels

  Membrane proteins
• Hormones

  Insulin
• Protection

  Antibodies
• What are globular proteins?


  Spherical shapes

  Soluble in water

  Made of 3D shapes

  An example is an enzyme
• What are fibrous proteins?


  Repetitive sequences of Amino Acids

  Insoluble in water

  Mainly structural

  An example is collagen
• Primary structure


  Sequence of a chain of amino acids

  They determine the ultimate shape and functions
• Secondary structure 


  Folding of the polypeptide chain into helixes or sheets

  NH+ and C=O on either side

  These form a weak hydrogen bond which causes the chain to twist into an a-helix or beta-pleated sheet
• Tertiary structure 


  3D folding pattern of a protein chain

  a-Helix can be twisted and folded further to give more complex 3D shapes

  Disulfide bonds are fairly strong

  Ionic bonds are formed between carboxylic and amino group, they are easily broken

  Hydrogen bonds are numerous but easily broken
• Quaternary structure


  Contains a number of individual polypeptide chains that are linked in various ways

  There may be a non protein

  An example of this is haemoglobin which contains an iron chain