Lecture 2

Question 1

Biopolymer

Answer 1

they have a defined beginning and end. They are synthesised in one direction only increasing the backbone. By convention, we write them from left to right. DNA have 5’ to 3’ while proteins are N to C. Some of the monomer is lost in polymerisation, leaving a ‘residue’ incorporated in the growing chain (for these molecules, the residue is usually the biggest part). Biopolymer synthesis relies on dehydration reactions and are anabolic.

Question 2

Peptide bond formation

Answer 2

two amino acids combine by a condensation mechanism to form a dipeptide. Very energetically unfavourable. Doesnt happen simultaneously.

Question 3

Peptide bond resonance

Answer 3

Once peptide bond forms, double bond doesnt stay. Electrons are shares more between the C and N and they have partial double-bond character. Backbone is polar due to partial charge. Partial charges encourage hydrogen bonding (protein structures) and partial double bond makes the peptide flat and rigid and planar.