Starter:
Reaction Rate
Temperature
pH
Enzyme Concentration
Substrate Concentration
Reaction Rate
Reaction Rate
Reaction Rate
Match the graph with the factors that affect enzymes
Jun 21­12:04 p.m.
Quick Quiz!
1. What is an enzyme?
2. What are the 4 main things that affect enzyme function?
3. Explain the difference between the lock and key and the Induced Fit model of enzyme function
Jun 23­8:44 a.m.
1
What do these have in common ?
Apr 8­7:02 p.m.
Quick Photosynthesis Review
a) Describe the purpose of photosynthesis
b) Explain how the structure AND location of chloroplasts affect the process of photosynthesis
Jun 21­12:07 p.m.
2
Nature and Properties of Enzymes
Biological­found within living organisms
Catalyst­substance which can speed up a chemical
reaction
Proteins in nature
Specific in action
• one kind of enzyme will catalyse only one
kind of chemical reaction
in
Prote
Apr 8­7:02 p.m.
Mechanism of enzyme action
• Active site : the place where substrate binds with the
enzyme
• Each active site can only allow specific substrate to fit
in
Substrate­the chemicals
in the reaction
Apr 8­7:02 p.m.
3
Enzymes work by lowering the activation energy required for a
reaction to get started.
Apr 8­7:02 p.m.
Enzymes
• Enzymes are biological catalysts. They are proteins which are found in living things, and it is their job to speed up reactions.
• Enzymes speed up reactions by reducing the amount of energy required for the reaction to get underway (activation energy).
• Each enzyme is specific to one type of reaction. An enzymes’ active site will only allow a specific substrate to bind.
Apr 8­7:02 p.m.
4
Theories...
• The Lock and Key Model describes the “fitting in” of specific substrate molecules into the active site of the enzyme.
• The Induced fit model describes the way that an enzyme changes shape when the substrate molecules lock and how this causes a reaction that leads to a product being formed.
Apr 8­7:02 p.m.
Action of enzyme
Apr 8­7:14 p.m.
5
Enzyme Function...
Factors affecting enzyme activities :
• Temperature
• pH
Factors affecting rate of enzymatic reactions :
• Temperature
• pH
• Enzyme concentration/Available surface area
• Substrate concentration/Available surface area
• Co­enzymes (Cofactors)
• enzyme inhibitors
Apr 8­7:02 p.m.
How temperature effects enzyme activity
Low temperature :
Lower reaction rate (and enzyme activity) Enzymes
become inactive
Higher temperature :
Higher reaction rate (and enzyme activity)
But too higher temperature leads to denaturing
Apr 8­7:02 p.m.
6
Effect of temperature on enzyme activity
denature
Apr 8­7:02 p.m.
Denaturation is a permanent process
When an enzyme is denatured, its catalytic function is lost permanently, it can never become active again.
Do not say it's DEAD!!
Apr 8­7:02 p.m.
7
Effect of pH on enzyme activity
Too extreme pH can destroy the enzymes
Optimum pH : the pH value at which the enzyme has
the highest activity
Pepsin in the stomach
Apr 8­7:02 p.m.
Enzyme Activities can be affected by:
• pH
• Temperature (collision theory)
Low temp can inactivate enzymes and high temp can denature them. Extreme pH can also denature enzymes.
The rate of enzyme reactions can be affected by:
• Temperature
• pH
Enzyme concentration / Available surface area
Substrate concentration / Available surface area
Apr 8­7:03 p.m.
8
Co-Enzymes (or Co Factors)
• Some enzymes are made of protein alone. Others consists of 2 parts: protein and another chemical called a co­factor.
• Co­enzymes are simply "helper" molecules that ensure the substrate attaches and that the chemical reaction occurs.
Apr 8­7:03 p.m.
Handout on enzymes
Jun 22­10:07 a.m.
9
Enzymes are found in both animals and plants, and have important roles in their metabolism.
(a) Describe the general purpose of enzymes.
(b) Explain the difference between the ‘lock and key’ and ‘induced fit’ models of enzyme activity. You may use diagrams in your answer if you wish.
Jun 21­12:06 p.m.
Home Learning:
Some of the factors that affect the rate of enzyme activity within cells include the amount of substrate, the enzyme concentration, coenzymes, and enzyme poisons (inhibitors). Discuss how any THREE of these factors can change the rate of activity within cells
Jun 21­12:07 p.m.
10
Jun 21­8:04 p.m.
11