1. ENZYMES

2. Why care about enzymes?
Enzymes are necessary for a variety of reactions – for photosynthesis, cell respiration, digestion, etc.
There are reactions in your body that would take over 200 years to complete if it wasn’t for enzymes
Enzymes lower activation energy or the amount of energy required to start a chemical reaction.

3. Chemical Reactions
When you eat, the food is broken down through chemical reactions performed by our metabolisms.
To write a chemical reaction: reactants  products
Reactants – what is put in/used & comes before the arrow
Products – what is made/produced & comes after the arrow
The arrow, , means yields, makes, creates, etc.
For example…
Chicken + noodles + broth  chicken noodle soup
reactants products
2H2 + O  2HO
2H2 & O are the reactants, HO is the product

4. Catalysts
Catalysts – anything which speeds up a reaction, written above the yield() sign
catalyst
Reactants Products
Enzymes – proteins that are catalysts in many chemical reactions, they speed up reactions occurring in the body

5. Things to know about enzymes
Enzymes are proteins that speed up reactions
Enzymes are specific – only able to be used for one type of reaction. The shape of the enzyme determines the specific reaction it catalyzes (speeds up)
Enzymes are reusable – they can be used over & over for the particular type of reaction
Enzymes lower activation energy or the amount of energy required to start a chemical reaction.

6. Activation Energy
Activation energy = the amount of energy required to start a chemical reaction
An enzyme lowers the amount of activation energy need to begin the reaction
THEREFORE the reaction is MORE likely to occur because less energy is needed to get it started
Activation energy E N R G Y
Course of Reaction
reactants
products
with an enzyme

7. An enzyme in a chemical reaction
Reactants are called substrates when an enzyme is present
The enzyme is a catalyst so it is written above the arrow
substrate
Active
site
Enzyme
Enzyme –Substrate Complex
Bonds
break in
Products
Active site
Enzyme
Product
Bonds form
Enzyme –Substrate Complex S U B T R A ES
The enzyme REMAINS the SAME throughout the chemical reaction. Substrates (reactants) are changed into products.

8. Things to remember!!! Active sites are found on the ENZYME
An enzyme & substrate together are known as an enzyme –substrate complex
Due to the enzyme shaping itself to fit a substrate, this is called induced-fit or lock & key (a key fits only one type of lock, just as an enzyme only fits one type of substrate)

9. How well enzymes work are effected by 3 things:
pH – different enzymes work best at certain pH’s between 0-14
Enzyme concentration – adding more enzyme helps speed up the reaction more. ***However, at a certain concentration adding more has no greater effect.
Enzymes work best at particular temperatures. If the temperature becomes too high the enzyme becomes denatured (broken down) and will no longer speed up the reaction

10. Temperature
At too high of a temperature, enzymes become denatured & will no longer work to speed up a reaction.
Temperature (°C)
Rate of
Reaction
The enzyme works best at this
temperature –indicated by the peak
At too high a temperature, the
enzyme becomes denatured
& does not work effectively