Factors affecting Enzymes

Enzymes

Enzymes are protein molecules made by living cells.

They are _______________ ________________ which speed up (but are not changed by) a chemical reaction.

Enzymes are coiled into a 3D shape (tertiary structure).

Enzymes posses an ____________ __________ - to which another molecule can bind.

The other molecule known as the _________________ fits perfectly into the active site to form an ENZYME - SUBSTRATE COMPLEX

Each enzyme acts on ________ substrate - They are specific- like a lock and a key .

Temperature and enzyme activity

At low temperatures the reaction occurs slowly because enzyme and substrate molecules are moving slowly.

The substrate and enzyme active site will not ____________ very often so binding is a rare event.

As temperature increase, collisions occur more frequently and with more energy - so the rate of reaction _____________.

BUT above a certain temperature, the structure of the enzyme changes.

The enzyme then loses its shape/unfolds as does the active site. This means the enzyme activity is reduced and the enzyme is said to be ________________.

At first, the substrate no longer fits into the active site very well and the reaction rate is just slowing down. Eventually though the substrate no longer fits the active site at all and so the reaction ________________.

The temperature at which there are maximum number of collisions is the _____________ ____________________.

pH and enzyme activity

Most enzymes work best at pH ______ - neutral