enzymes lab 5. enzymes reaction characteristics – enzymes are catalysts: substances that speed up...

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Enzymes Lab 5

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Page 1: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Enzymes

Lab 5

Page 2: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Enzymes

• Reaction characteristics– Enzymes are catalysts: substances that speed up

or facilitate a chemical reaction by LOWERING the activation energy

– Energy of Activation: Amount of energy needed to start a reaction

Page 3: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Activation Energy

Endergonic Reaction Exergonic ReactionRequires energy Releases energy

Page 4: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Ways to Lower the Energy of Activation

• Enzymes– Protein catalysts that lower the amount of energy

needed to get the chemical reaction going– They maintain their original chemical composition while

causing a change in the substrate (reactant)– The specific shape of the enzyme allows it to catalyze

only one reaction– Active site = place on the enzyme that binds substrate– Since the enzyme does NOT change its shape, it is

REUSABLE

Page 5: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation
Page 6: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation
Page 7: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation
Page 8: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Altering the Rate of an Enzymatic Reaction

1. Temperature2. pH

Page 9: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Altering Temperature• Gradual ↑ in temperature will INCREASE the rate of the

reaction – How? By an increase in the speed at which the molecules are

moving– This results in increased collisions of the enzyme and substrate

• Extremely low temperatures will SLOW DOWN or STOP the reaction– Why? The enzyme and substrate are moving too slow to collide

• Extremely high temperatures will STOP the reaction– Why? Because the enzyme will be denatured!

Page 10: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Altering pH

• Alterations in pH will STOP the reaction because the enzyme will be denatured!

• Remember, a small pH change does NOT correlate with a small change in the pH of the environment!!– Why? pH scale is logarithmic

Page 11: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation
Page 12: Enzymes Lab 5. Enzymes Reaction characteristics – Enzymes are catalysts: substances that speed up or facilitate a chemical reaction by LOWERING the activation

Enzyme Questions• The presence of an enzyme _____ the required

energy of activation of a chemical reaction.• Generally, as the amount of substrate is increased,

the rate of the reaction _____.• Raising the temperature to over 50C ___ the rate of

an enzymatic reaction.• Lowering the pH for an enzyme that works best in a

highly acidic environment ___ the rate for the reaction.