Question

Enzymes must be the correct shape to work or they will not be able to fit to the substrate.

Answer 1

Answer) Enzymes are the biocatalysts which have efficiency, specificity and have a mode of regulation. For a successful progression of a reaction, enzymes must bind effectively to its counterpart or substrate. To explain this, a renowned scientist Emil Fischer proposed the "Lock and Key" hypothesis. According to this hypothesis, just like the complementarity of a set of lock and key, enzymes and their respective substrates are complementary to each other. Hence any change in the enzyme structure alters its binding with the substrate, therefore halting the reaction.  

Substrates bind with the enzyme at the "active site" of the enzyme. Each active site of any enzyme bears some specific amino acid composition. These amino acids have their respective side chains and structure, if there is any change in this amino acid content, then the shape of the active site is altered. This alteration in shape of the active site inhibits the substrate to fit in the active site of the enzyme, thereby stopping the reaction.