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12 Cards in this Set

  • Front
  • Back
• Outline the reaction by which amino acids are joined together.
Condensation reaction. COOH and NH2
• Sketch a trimeric peptide, illustrating the amino -terminus, carboxyl terminus and side chains.
Need image.
• Give examples of the post-translation modifications of amino acids, with reference to glycosylation, hydroxylation and carboxylation.
o Hydroxylation:
 Proline becomes hydroxy-proline: collagen fibres
 The extra hydroxyl helps stabilise
 (vit C, scurvy)
o Glycosylation
 Sugars are added to asparagine residues of protein (look into this ?)
 Makes them more soluble/prevents degradation
o Carboxylation
 Glutatamate  gamma-carboxyglutamate
 Essential to clotting cascade (warfarin inhibits)
• Understand the concepts of primary structure, secondary structure, tertiary structure & quaternary structure with respect to proteins.
o Don’t forget domains
• Distinguish between an α-helix and a β-pleated sheet and appreciate the bonds that stabilise their formation.
o Hydrogen bonds stabilise helices and pleated sheets.
• Appreciate the different types of bond that combine to stabilise a particular protein conformation.
o Disulphide Bridges
 Covalent bonds
 Occur when cysteine side chains are “oxidised”?
 Makes a covalent link between two amino acids
o Hydrogen Bonds, of course
o Ionic Interactions
 Due to electrostatic attractions between charged side chains
 Relatively strong (especially if in hydrophobic interior)
o Van der Waals
o Hydrophobic interactions
 Major driving force
o Ionic Interactions
 Due to electrostatic attractions between charged side chains
 Relatively strong (especially if in hydrophobic interior)
1st law of thermodynamics
Energy can neither be created nor destroyed; only transferred/formed/etc
2nd law of Thermodynamics
o 2nd: In any isolated system, disorder can only increase (entropy)
• Describe how oxidation and reduction involve the transfer of electrons
Redox potentials/etc. Hydrogen half-cell/etc
• Explain the concept of free energy and how we can use changes in free energy to predict the outcome of a reaction.
o Free energy is the amount of energy in a molecule that could perform useful work at a constant temperature. Measures entropy/enthalpy
If Gibbs is negative, reaction will be spontaneous
• Draw the chemical structure of ATP and explain how it acts as a carrier of free energy and is used to couple energetically unfavourable reactions
o Its energetically favourable reaction coupled to an unfavourable reaction can make an overall favourable one. So long as overall gibbs is negative.
o ATP to ADP is very favourable (-31kjmol-1)