topic 2

The expected Learning Outcomes for this topic are:

  1. For each of the four major classes of biological molecules, recognise the chemical structures and components of those structures, and give examples of names from each category:

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  • lipids/fats

  • sugars/carbohydrates/saccharides

  • nucleic acids (RNA/DNA)

  • amino acids (proteins)

  1. Understand that the basis of the DNA genetic code is the linear sequence of nucleotides: adenosine (A), guanine (G), cytosine (C) and thymine (T) in the DNA polymer (or strand). In RNA, uracil (U) is substituted in place of thymine.

  2. Describe the overall structure of the DNA double helix including the stacking of base pairs within the core of the structure, the base pair rules (A-T and G-C), the phosphodiester backbone and the anti-parallel nature of the two strands in the double helix.

  3. Apply the principles of base pairing and the anti-parallel nature of the double helix to infer the sequence of the second strand of DNA, including correct identification and application of 5'-3' orientation.

  4. Reverse Complement: inferring sequence of 2nd DNA strand, including 5'-3' orientation. This applies the principles of base pairing and the anti-parallel nature of the double helix.

  5. Understand that the function of a proteins is dependent on its three dimensional structure and that in turn this is dependent on the linear sequence of amino acids in the protein polymer.

  6. Know that the peptide bond joins amino acids in the protein polymer.

  7. Recognise the overall structure of amino acids including the "backbone" and "side chain" components.

  8. Recognise the names of the 20 naturally-occurring amino acids (but you do not need to know the 3-letter and 1-letter abbreviations).

  9. Describe the four levels of protein structure (1°, 2°, 3° and 4°) and how they interrelate describe the overall structure of a protein.

  10. Explain the chemical interactions that drive proteins to fold into stable 3-dimensional structures. This includes the preference for polar side chains to interact with water molecules and non-polar side chains to avoid interactions with water. The backbone polar atoms need to engage in hydrogen bonding and this is achieved through the 2° structures alpha-helix and beta-strand.

  11. Explain the importance of covalent disulphide bonds and non-covalent bonds in the formation and stability of the 3-dimensional structures of proteins.

Recognise that in water soluble proteins the non-polar amino acids form the hydrophobic core of the protein with the hydrophilic polar amino acids on the surface. For proteins embedded in the lipid membrane, the opposite is true, the non-polar amino acids are on the surface to interact with lipids and the polar amino acids are in a water-filled pore or at the outer edges beyond the membrane bilayer.

 

 

 

 

 

 

 

  1. State the energy exchange within chemical reactions including applying the terms: endergonic, exergonic and Gibbs free energy.

  2. Explain how ATP is used in a coupled reaction to facilitate an otherwise endergonic reaction.

  3. Explain how enzymes have all the properties expected of catalysts and how they can lower the activation energy barrier of reactions.

  4. Explain the difference between competitive and non-competitive inhibitors.