ENZYMES & ENERGY ACADEMIC BIOLOGY

__________________________________________________________________________________________________________________________________________________ To release chemical energy, cells must have a way to break and form chemical bonds. ___________________________________________________________________________________________________________________________________________________ I.Enzymes (Catalysts) –Specialized proteins that help to speed up or start a reaction without being changed themselves. II.Activation Energy - The energy required to start a reaction. - Enzymes lower this amount.

Activation Energy Diagram 2:

Activation Energy Diagram 1:

Endergonic vs. Exergonic Exergonic Reactions  Release energy, do not require any energy Endergonic Reactions  Absorb energy, require energy to occur

III.Characteristics of Enzymes - Enzymes are extremely specific & will only work for one type of reaction. Lock and Key - Enzymes are reusable / recyclable. - Each type of enzyme only works within a narrow pH & temperature range.

IV.How Do Enzymes Work? - A reaction requires the following: 1. An enzyme 2. A Substrate - What an enzyme acts on. (The Reactants) 3. Favorable Conditions

Steps: 1.A substrate binds to the active site of an enzyme forming the……… enzyme-substrate complex. - Active site: Location on an enzyme where a substrate(s) binds to. 2.When a substrate binds to an enzyme, a change in the shape of the enzyme occurs, resulting in the formation of a new product(s). (Induced Fit) 3.Enzyme goes on to perform a new reaction.

Cycle of Enzyme Activity:

Animation hill.com/sites/ /student_view0/ chapter2/animation__how_enzymes_work. htmlhttp://highered.mcgraw- hill.com/sites/ /student_view0/ chapter2/animation__how_enzymes_work. html

Environmental Effects on Enzymes pH Temperature Substrate Concentration

Denaturing An enzyme becomes denatured when its bonds are broken and shape is changed. Substrate can no longer fit. Occurs when temperature is increased or pH level is unfavorable.

Regulation of Enzyme Activity Inhibition- a molecule binds to an enzyme preventing activity. Competitive inhibition- inhibitor binds at the active site preventing the substrate from binding.

Regulation Cont. Non-competitive inhibition (allosteric)- inhibitor binds at a site other then the active site, changes the shape of the enzyme and prevents substrate binding.Non-competitive inhibition (allosteric)- inhibitor binds at a site other then the active site, changes the shape of the enzyme and prevents substrate binding.