PCOL3012 - Drug Design Exam Questions & Answers 2025 A+

PCOL3012 - Drug Design Exam Questions & Answers 2025 A+ 1. Define: chirality, enantiomer, racemic mixture, optical isomer and chiral carbon - ANS-Chirality: chiral molecules are non-superimposable on their mirror images. This means their geometric orientation, depending on the groups attached can have a big impact on their biological activity. Enantiomer: mirror images that are non-superimposable (cannot fold on top of each other) Racemic mixture: mixture of S- and R-enantiomers Optical isomer: mirror images, cannot be super-imposed Chiral carbon: a carbon with 4 different groups attached to it, asymmetric carbon 1. Explain the impact chirality can have on how a drug behaves - ANS-Chirality is determined by whether hydrogen atoms point up or down. This changes the way a biological system recognises the molecule, thus resulting in different biological activity. Thalidomide in vitro could be an R-enantiomer, having no negative effect on foetal development and helping nausea, but in vivo would convert to S-enantiomer, causing harm to the foetus. 2. Types of isomers - ANS-Geometric: restricted rotation around a double bond (trans or cis) Structural: same groups but different connectivity Configurational: need to break and reform covalent bonds to convert between the isomers Conformational: rotation around a single bond is needed to convert between (same connectivity)