CHAPTER 5.5

ENZYMES ARE PROTEINS THAT SPEED UP SPECIFIC REACTIONS IN CELLS

ENZYMES AND ACTIVATION ENERGY

• Activation Energy- the energy needed to start a reaction

• EXAMPLE: Candle Burning• If you heat something to lower the activation

energy structures in the cell can become destroyed

• Therefore, we need enzymes!

ENZYMES AND ACTIVATION ENERGY

• Catalysts- substances that speed up chemical reactions

• Enzyme- the main catalyst of chemical reactions

Enzymes

• Foods have Enzymes! • Speed up reactions! • Example: Fruits and Vegetables, Nuts, Seeds

What are enzymes?

• Your body has lots of reactions!

• Enzymes: Special Proteins that speed up specific reactions

• End in ASE – Ex. Lactase digest lactose

• HOW?

Enzymes Lower Activation EnergyThe energy needed to get a reaction started

Lower the Activation Energy

• Activation energy is the “start up” energy of a reaction

• Enzymes speed up reactions by lowering the activation energy

• They do not raise the temp!

8

Enzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activation

Without EnzymeWith Enzyme

Elephant Toothpaste

• http://www.youtube.com/watch?v=7qtX6XgDeDY

HOW ENZYMES WORKEnzymes are Specific

• The shape of an enzyme fits only particular molecules

• Substrate- a specific reactant to an enzyme

• Active Site- the area the substrate fits in

Reaction for enzyme -Put together substrates

Find the Enzyme, Substrate, and Product For Each Substance

Online Activity 5.5

• Worksheet

Enzymes

http://www.youtube.com/watch?v=hoBhOdQV7vw

Effects on Enzymes

• Temperature • pH

Temperature• Enzymes are PROTEIN • Heat too high they can

denature

pH

• Enzymes work best at an ‘optimal’ pH

Enzymes are Reusable

• Enzymes will speed the reaction for a substrate

• It will release the product and will work on another substrate

Examples

• Lipase • Protease • Lactase • Sucrase • Amylase

• Life is not possible without enzymes! !!!!!!!