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Enzymes
What are Enzymes?
• Enzymes are proteins that speed up chemical reactions.
• They cause change, so they are also called catalysts.– Reactions can occur without enzymes, but they may
take a really long time. Enzymes lower the amount of energy needed for the reaction to take place.
– http://www.stolaf.edu/people/giannini/flashanimat/enzymes/prox-orien.swf
Enzyme Labeling
Enzyme Labeling
1.
2.
3.
What can enzymes do?• Some enzymes can break down
substances into smaller parts.
• Other enzymes can build substances that cells need.
There are thousands of enzymes!Why?• Each enzyme is specific for one substrate
(the substance it binds to). • The enzyme and substrate fit together like
a lock and a key.• When the substrate andenzyme bind, the enzymeactually changes its shapea little.
http://www.stolaf.edu/people/giannini/flashanimat/enzymes/enzyme.swf
Enzymes are “green”!
• Once an enzyme has finished with helping one reaction, it’s ready for another.
• Enzymes are reusable.
http://www.biotopics.co.uk/other/anenz.html
Do enzymes always work?
• NO - There are two factors that can denature enzymes, or alter the enzyme’s shape and stop it from doing its job. They are:– Temperature http://
www.biotopics.co.uk/other/andnat.html – pH
http://www.phschool.com/science/biology_place/labbench/lab2/ph.html
(Denatured enzyme)http://www.biotopics.co.uk/other/aninac.html
Has the enzyme been destroyed?• “Denatured” does not mean the enzyme
has been destroyed. It has simply lost its shape.
• Enzymes can be “renatured.” If they are returned to normal conditions, they will regain function.
When do enzymes work best?
• Enzymes work best at an optimal temperature and pH level specific for that enzyme. Not all enzymes function at the same temp. or pH.
Amylase- enzyme in mouth
Pepsin- enzyme in stomach
Arginase- enzyme in intestines
Which ones work at the same pH?
How do you know it’s an enzyme?Class Function
1. Oxidoreductase Catalyse redox reactions
2. TransferasesCatalyse transfer of a molecular
group from one molecule to another
3. HydrolasesCatalyse bond cleavage by the
introduction of water
4. Lysases
Catalyse reactions involving the removal of a group to form a double bond or addition of a group to a double bond
5. IsomerasesCatalyse reactions involving
intramolecular rearrangements
6. Ligases/SynthesasesCatalyse reactions joining
together two molecules
What do all these enzyme names have in common?
More Enzyme Animations
• http://www.teachertube.com/view_video.php?viewkey=1879aed110525c185ff3
• http://www.lew-port.com/10712041113402793/lib/10712041113402793/Animations/Enzyme_activity.html
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html