Enzymes are biological catalysts that speed up chemical reactions by providing an alternative pathway with a lower actviation energy.
By looking at the graph above, you can see that enzymes lower the activation energy of an enzyme catalysed reaction. Lower activation energy enables substrate molecules to be converted to product more quickly.
Enzymes are specific. They have active sites which react with substrates that have a similar shape to their active site.
When studying enzymes, I came across two hypothesis: The Lock and Key Hypothesis and Induced Fit Hypothesis.
LOCK AND KEY
This picture shows the basic concept of the lock and key hypothesis.
The subsrate fits perfectly into the enzyme-key into lock, the key being the substrate while the enzyme active site being the lock- forming an enzyme-substrate complex. Products form which can no longer fit into the active site and are released.
INDUCED FIT HYPOTHESIS
For the Induced Fit model, the active site shape changes slightly for the substrate to fit perfectly and form an enzyme- substrate complex.