Flow of energy through life Life is built
Flow of energy through life § Life is built on chemical reactions Regents Biology
Regents Biology
Enzymes: are “Helper” Protein molecules that reduce the amount of energy needed for chemical reactions to take place (Catalyst) Regents Biology 2009 -2010
Examples § synthesis + enzyme § hydrolysis enzyme Regents Biology +
Why do enzymes speed up reactions? energy (k. J) They lower the activation energy of a reaction. Activation energy is the energy needed to start a reaction. Ea without enzyme Ea with enzyme reaction (time) Different reactions have different activation energies. Regents Biology
Enzymes are proteins § Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job u enzymes are named for the reaction they help u Oh, I get it! They end in -ase § § Regents Biology sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA
Enzymes aren’t used up § Enzymes are not changed by the reaction used only temporarily u re-used again for the same reaction with other molecules u very little enzyme needed to help in many reactions u substrate active site Regents Biology product enzyme
The lock and key model Regents Biology
Enzyme vocabulary § Enzyme u helper protein molecule § Substrate u molecule that enzymes work on § Products u what the enzyme helps produce from the reaction § Active site u part of enzyme that substrate molecule fits into Regents Biology
What affects enzyme action § Correct protein structure correct order of amino acids u why? enzyme has to be right shape u § Temperature u why? enzyme has to be right shape § p. H (acids & bases) u why? enzyme has to be right shape Regents Biology
Order of amino acids § Wrong order = wrong shape = can’t do its job! chain of amino acids DNA folded protein right shape! folded protein chain of amino acids DNA Regents Biology wrong shape!
Temperature § Effect on rates of enzyme activity Optimum temperature § greatest number of collisions between enzyme & substrate § human enzymes w 35°- 40°C (body temp = 37°C) u Raise temperature (boiling) § denature protein = unfold = lose shape u Lower temperature T° § molecules move slower § fewer collisions between enzyme & Regents Biology substrate u
Temperature reaction rate human enzymes 37° temperature Regents Biology What’s happening here? !
p. H § Effect on rates of enzyme activity u changes in p. H changes protein shape u most human enzymes = p. H 6 -8 § depends on where in body § pepsin (stomach) = p. H 3 § trypsin (small intestines) = p. H 8 Regents Biology
p. H intestines trypsin What’s happening here? ! reaction rate stomach pepsin 0 Regents Biology 1 2 3 4 5 6 p. H 7 8 9 10 11 12 13 14
For enzymes… What matters? SHAPE! Regents Biology 2009 -2010
Enzymes: true or false? Regents Biology
Regents Biology
Let’s build some Enzyme Models! Regents Biology 2009 -2010
Regents Biology
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