Download Enzyme Notes Name: . What are enzymes? • Enzymes are which act

Enzyme Notes
Name: __________________________.
What are enzymes?
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Enzymes are ______________________________ which act as biological catalysts.
– A catalyst is a substance that starts or speeds up a chemical reaction.
– It lowers the activation energy required for the reaction to take place.
Enzymes are used by cells to trigger and control ___________________________________________.
Without enzymes, several reactions in cells would never occur or happen too slowly to be useful.
What is the monomer of an enzyme? ___________________________.
What does the function of an enzyme (or any protein) depend on? _________________________.
What do nucleic acids (DNA) have to do with enzymes? _____________________________________________
___________________________________________________________________________________________.
What is a chemical reaction?
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The process of changing one set of chemicals (___________________) into another set of chemicals
(_______________________) by rearranging the atoms.
The bonds joining the reactants are broken and new bonds are formed in the products.
Activation energy is the amount of energy needed to ________________________ a chemical reaction.
How do Enzymes Work?
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Enzymes are the instigators!
Enzymes ______________ (speed up)
chemical reactions between reactants
(substrates) that form new products.
After the reaction, enzymes
are ____________ and ready
to catalyze the next reaction.
How do enzymes speed up reactions?
__________________________________
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What is a substrate?
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Enzymes bind to molecules called
____________________________________
The(se) substrate(s) are the reactants in the
chemical reaction that is catalyzed by the enzyme.
Example: Typically something we ingest that
needs to be broken down further for use by the
body like Lactose from Cow’s milk. (Done by
Lactase)
Label the enzymatic reaction above.
Enzyme activity: Locks & Keys / Catch & Release
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The site on the enzyme where the substrates bind is called the _________________________________
The substrate(s) enters the active site which becomes the enzyme-substrate complex.
The ______________ of an enzyme is so specific that generally only one enzyme will work for one substrate(s).
The fit is so exact that the active site and substrate(s) act like a ______________________________.
After undergoing a reaction in the enzyme-substrate complex, the changed substrate is released as a ___________
to be used by the body.
Since only the _________________ changes during the reaction, the enzyme can be reused again and again.
Recall: Based on what you know about proteins, what is it about enzymes that allows each one to be specific to a
single substrate? (ie: how are there so many different enzymes to fit all of the different substrates in our bodies?)
___________________________________________________________________________________________.
Induced Fit Hypothesis: Enzymes can change ______________ slightly to fit the substrate a little better
(like a hand in a glove).
What factors affect enzyme function?
1. Enzymes work best at specific __________________________________ and _________________.
 Extreme temperature and pH can change the shape of the enzyme, affecting the binding “active” site.
o Recall: What is the term for destroying an enzymes (or any protein)? ______________________.
 Enzymes in our body work best at 37°C (98.6°F) and at a pH between 6.5 and 7.5.
2. Cells contain proteins that turn enzymes on or off during critical stages of development.
Review: enzymes are catalytic ___________________
Enzymes…
1. …speed up reaction rate but do not change the reaction.
2. …are very specific.
3. …work like locks & keys.
4. …are unchanged by the reaction.
5. …function depends on structure (shape)
6. … are sensitive to changes in temperature and pH.
The suffix –ase = enzyme. Examples: _______________________________________________________________.
Your Turn! Phenolase in apples
Question/Problem: What are the effects of pH on enzymatic activity?
Observation/Control: What initial observations can you make about the effect of phenolase on an apple slice?
______________________________________________________________________________.
Hypothesis:
1. What do you expect to see on the apple with lemon juice? ____________________________________________.
2. What effect do you think that the lemon juice will have on the enzyme phenolase in apples? What is the pH of
lemon juice? How does this affect enzymatic activity? _______________________________________________.
Experiment: Cut an apple in half. Leave one half alone as a (-) control. Add lemon juice to the other half and let it sit.
Results: What happened to the apple with the lemon juice on it? _____________________________________________.
Conclusions:
1. Does this observation support your hypothesis? ____________________________________________________.
2. What do you think happened to phenolase in such an acidic environment? ________________________________
___________________________________________________________________________________________.