Nature chose polyamides to form proteins because polyamides are made through condensation reactions of amino acids that eliminate water molecules. These protein structures have chains stabilized by hydrogen bonding between nitrogen atoms on one chain and oxygen atoms from the carbonyl groups on another chain. This hydrogen bonding stabilizes the protein structure in a way that is not possible with esters. Nature selects monosubstituted amides over disubstituted amides for proteins due to disubstitution increasing steric effects that destabilize the protein chains and disrupt important hydrogen bonding between chains, which stabilize the primary, secondary, and quaternary protein structures.

1. Please answer both
Solution
18 . Nature chose polyamides to form proteins. This is bacause the polamides are made by
the condensation of the amino acis with the elimination of the small molecules water. These
proteins have different strucures having chains which are stabilized by hydrogen bonding
between nitrogen atom of one chain wth oxtgen atom of C=O of another chain. thus the
structure gets stabilised.This not possible in esters.
19.The nature chose monosubstituted amides instead disubstituted because conformations
in proteins stabilize the protein structures. Due to the disubstitution the steric factor
increases destabilising the protein chains. disturbing hydrogen bonding in proteins chains
having primary, seconary & quaternary structues.