The Lock-and-key mechanism was first proposed by Emil Fischer which described as the enzymatic reactions whereby an enzyme with a single substrate binds temporarily to form a substrate complex.
The lock-and-key mechanism is usually associated with the complementary shapes of an enzyme with a single substrate, wherein the lock that is being referred to is the enzyme and the substrate is the key. One right sized substrate (key) fits into the active site (key hole) of the enzyme (lock).
The active site which is mentioned above is structurally complementary to the substrate. This is the temporary binding site on the enzymes. Just like a lock and key, the enzyme as the lock and the substrate as the key is said to fit together.
Answer:
On the exterior of the cell.
Explanation:
The black spots as mentioned in the given case would appear on the exterior of the cell after three hours, which suggests that the proteins or the enzymes had been discharged from the pancreatic cell. The mentioned method of labeling and then chasing the component is known as a pulse-chase experiment.
In this experiment, the labeled compounds are used to follow the dynamics of cellular pathways and procedures. The molecules in a cell get produced and degraded spontaneously at various rates. These changes in the localization of the molecule and its expression levels with time can be determined by exposing or pulsing cells to a labeled compound.
After this the cells are exposed sequentially to the same compound unlabeled, the process is termed as the chase. The compounds are generally labeled with fluorescent dyes or radioisotopes.
