1. By Marian and Emma-Rose
ENZYMES
By Marian and Emma-Rose
I found a useful site for information and diagrams:

2. The Role of Enzymes
1)To help chemical reactions to occur / to affect or modify the rate of chemical reactions.
Reactions can still occur without the presence of enzymes but it would not be fast enough to support life.
Enzymes are organic catalysts that are the principal regulators of most chemical activity in living systems
Catalysts are substances that bring about reaction without being changed itself
chemical reactions requires specific enzymes

3. STRUCTURE Large complex proteins Protein Nature Active site
Tip: Names of Enzymes often end in “-ase”.
Large complex proteins
One or more polypeptide chains
Made of amino acids
Protein Nature
Either exclusively proteins or proteins with non-protein parts
Coenzymes
vitamins
Active site
Enzyme molecules are larger than what they interact with
The way the chains fold results in formation of pockets
Reacting molecules fit into
THIS IS THE ACTIVE SITE

4. Enzyme Substrate Complex
For an enzyme to affect rate of reaction
Enzyme must form temporary association with substance(s) whose reaction rate it affects
Substrates
Association between enzyme and substrate thought to involve close, physical association between molecules
Enzyme-substrate complex
As enzyme substrate forms enzyme action takes place
Completion of reaction
Enzyme and products separate
Enzyme molecule now available to form additional complexes
Although enzymes may be reused in cells, they eventually are destroyed and new ones must be synthesized

5. Function:
-Evidence has accumulated so there can be a model made of enzyme action
-Scientists don’t exactly know how enzymes work so they use models to infer
-Useful in visualising the nature of its function
- Is consistent with available evidence function
There are two different models that show inferences of the enzyme functions.
“Lock and Key” Model
Induced Fit Model

6. “Lock and Key” Model
The Lock and Key model shows that enzymes can only interact with specific substrates. Like a lock and key only one kind of substrate can fit into a certain enzyme.

7. Induced Fit Model
The induced fit model show that the enzymes can change their shape in order to better fit the substrate it is with.

8. Some Factors Affecting Enzyme Action
Small amounts of enzyme can cause reaction of large quantities of substrate
For enzyme-substrate complex to form and reaction to occur is short
1 enzyme molecule can catalyze thousands of substrate reactions each second
The enzyme can only perform one reaction at a time
Enzymes enable cell reactions to take place at normal temperatures
Many chemical reactions take place slowly at regular temperatures
Can be speeded up raising temperature
High temperatures can kill living cells
Enzymes speed up reactions without high temperatures
Enzymes work best at certain temperature
If at low temperature reaction is slow
If at high temperature reaction forms at faster rate but enzyme starts to break down
Denaturation
Optimum temperature is where enzyme is most effective
Close to normal cell temperature

9. Factors that Influence Enzymes
Enzymes do not have a fixed rate of reaction time. Certain environmental factors affect the way the rate of enzyme action. Some factors that vary the rate of enzyme action are pH, temperature and relative amounts of enzyme and substrate.

10. Review Questions: b) False
An enzyme speeds up chemical reaction in the cell, but can only be used once.
2) An enzyme can bind only one reactant at a time.
3) Which of the following can only bind to the active site of an enzyme?
4) Enzymes are ____ ) Enzymes are inorganic.
True
b) False
True
b) False
lipids
b) any other enzyme
c) Product
d) substrate
Lipids
Carbohydrates
Nucleic Acids
True
b) False
d) Proteins

11. About the Food Sugars in grapes The enzyme sucrase digests glucose
Fructose
The enzyme sucrase digests glucose

12. Links to pictures
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diagram
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- tempature graph pH
- Substrate concentration
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diagram
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