Lock and key refers to 1.An enzyme-substrate complex with a fixed shape active site that allows a single substrate to bind 2.

Lock and key refers to

1.An enzyme-substrate complex with a fixed shape active site that allows a single substrate to bind

2.An enzyme-substrate complex with flexible shape active site that allows multiple substrates to bind

3.How proteins are combined to create enzymes

4.How you protect your valuables

5.Both 1 and 2