biochem

• Amino acid structures and properties

  The structures are as they would be at cellular pH (approx. pH 7): the alpha amino and alpha carboxyl groups are charged, and the side chains of some amino acids are charged
• The red boxes demarcate the side chains
• Classification of amino acid side chains

  • Non-polar hydrophobic
  • Polar hydrophilic
  • Uncharged
  • Acidic (negatively charged at pH 7)
  • Basic (positively charged at pH 7)
• The classification of some amino acids is debatable, in which case both classifications are given
• You should know the names, three letter and one letter codes of all 20 amino acids, and their classifications
• The amino acids with names in red are the ones you should learn to draw, the others you should recognise
• Glycine


  Non-polar but not strongly hydrophobic (small)
• Alanine


  Non-polar hydrophobic
• Tyrosine


  Non-polar hydrophobic/ Hydrophilic (uncharged polar)
• Serine


  Hydrophilic, Uncharged polar
• Cysteine


  Non-polar hydrophobic/ Hydrophilic (uncharged polar)
• Aspartic acid/Aspartate


  Hydrophilic, Charged, acidic, Carboxylate group
• Glutamic acid/Glutamate


  Hydrophilic, Charged, acidic, Carboxylate group
• Asparagine


  Hydrophilic, Uncharged polar, Amide group
• Glutamine


  Hydrophilic, Uncharged polar, Amide group
• Lysine


  Hydrophilic, Charged, basic
• Arginine


  Hydrophilic, Charged, basic, Guanidino group
• Histidine


  Hydrophilic, Charged, basic/ uncharged polar (easily gains or loses a proton at pH 7), Imidazole group
• Exam Revision Session 4BBY1013 Biochemistry Faculty of Life Sciences & Medicine Department of Biochemistry Dr. Lauren Albee
• Proline


  Non-polar hydrophobic, Side chain bonded to α-amino nitrogen
• KEATS! Best source for information https://keats.kcl.ac.uk/course/view.php?id=50621
• Valine


  Non-polar hydrophobic
• Leucine


  Non-polar hydrophobic
• Isoleucine


  Non-polar hydrophobic
• CHECK YOUR EXAM TIMETABLE! 4BBY1013 exam currently scheduled for May 8th, 2024 at ExCeL center – subject to change, use your timetable!!!
• Tryptophan


  Non-polar hydrophobic
• You are allowed into the exam hall 30 minutes before you start, late comers will NOT be given extra time
• 1 hour, 50 MCQ, single best answer
• Methionine


  Non-polar hydrophobic
• Threonine


  Hydrophilic, Uncharged polar
• Content covered

  • All lecture material is fair game for questions
  • All material covered in Problem Solving Workshops (PSWs) is fair game
  • All material covered in practicals is fair game
  • Formative and summative coursework are NOT included in the exam
• We have asked you about the key points, focus on the main information.
• Not all exam information will be covered, today. This is to highlight some of the key information.
• This lecture introduces the structural features and properties of some biological macromolecules. After this lecture you should be able to:
• Outline the chemical features and properties of the four main classes of biological molecules (carbohydrates, lipids, nucleic acids and proteins)

  • Recognise that complex biological macromolecules are composed of smaller biomolecules
• Distinguish aldose and ketose sugars and explain the formation of ring structures of monosaccharides

  1. Distinguish isomeric forms of glucose: enantiomers, anomers and epimers

  2. Recognise and name correctly α and β glycosidic bonds in disaccharides and polysaccharides

  3. Draw the chemical structure of a representative amino acid (alanine) and a peptide bond between two amino acid residues

  4. Explain how amino acids are grouped according to the characteristics of their side chains
• Four main families of small organic molecules form monomeric building blocks for the formation of biological macromolecules

  • Sugars and fatty acids: energy source
  • Nucleotide (ATP): energy carrier
• Monosaccharides


  Classed as aldoses or ketoses, depending on whether they contain an aldehyde or a ketone group
• Carbohydrates


  1. Formed by glycosidic bonds between monosaccharides

  2. The α- or β-configuration is "locked" when the bond is formed
• Complex carbohydrates


  • α 1→4 linkage
  • β 1→4 linkage