Enzymes: “Helper” Protein molecules 2009-2010

Chemical Reactions When bonds are broken and reformed to make different substances. EX: Reactants Products C6H12O6 + 6O2 6CO2 + 6H2O Remember, energy is stored in the bonds of the compounds. Reactants are also called raw materials – They need to know this term. Have them tell you the reactants and products of the above equation.

Chemical reactions of life Processes of life building molecules synthesis breaking down molecules digestion + +

What is needed to start a reaction? Energy absorbed Activation energy Activation Energy: energy required to get a reaction started Point out the high amount of energy needed with reaction in graph. The activation energy on the graph comes in when you click the mouse – the purpose is to get the answer from them first. – Remember enzyme demo Energy released reactant Products

Nothing works without enzymes! How important are enzymes? all chemical reactions in living organisms require enzymes to work building molecules synthesis enzymes breaking down molecules digestive enzymes Catalysts (enzyme): organic molecule that lowers activation energy = speed up of chemical reactions enzyme + enzyme We can’t live without enzymes! +

Catabolic Reaction (DIGESTION) Is the breakdown of a complex molecule into simpler substances These reactions RELEASE energy

Anabolic Reaction (SYNTHESIS) The combining of simple molecules into a more complex ones This reaction builds new molecules and/or STORES energy

Examples anabolic enzyme + catabolic enzyme +

Enzymes are proteins Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job enzymes are named for the reaction they help sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA Oh, I get it! They end in -ase

Enzymes aren’t used up Enzymes are NOT changed by the reaction used only temporarily re-used again for the same reaction with other molecules very little enzyme needed to help in many reactions substrate product active site enzyme

It’s shape that matters! Lock & Key Theory shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

What Affects Enzyme Activity Temperature: pH: Concentration: 3 7 5 9 11 13 Neutral Battery Acid Bleach Blood (7.5) Temperature: all enzymes have an optimal temp they work best at pH: acidity/alkalinity can increase or decrease the function of an enzyme Concentration: Increasing the concentration of the enzyme can increase the rate of the chemical reaction

Temperature Effect on rates of enzyme activity Optimum temperature greatest number of collisions between enzyme & substrate human enzymes 35°- 40°C (body temp = 37°C) Raise temperature (boiling) denature protein = unfold = lose shape Lower temperature molecules move slower fewer collisions between enzyme & substrate

Temperature human enzymes reaction rate temperature 37° What’s happening here?! 37° reaction rate temperature

pH Effect on rates of enzyme activity changes in pH changes protein shape most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

pH stomach pepsin intestines trypsin reaction rate pH 1 2 3 4 5 6 7 8 What’s happening here?! reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

Concentration Two ways concentration can affect reaction rates Increase substrate concentration will increase reaction rate (only to a point) Increase enzyme concentration will increase reaction rate (only to a point)

Concentration reaction rate concentration 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 concentration

Denature When enzymes are exposed to extremes in pH or high temperatures, they can denature When denatured, an enzyme will no longer function, due to a change in the structure of the enzyme This is why running high fevers for extended time is cause for concern

Competitive Inhibition Competitive Inhibition: is a form of enzyme inhibition where binding of the inhibitor to the active site on the enzyme prevents binding of the substrate

Noncompetitive Inhibition Noncompetitive Inhibition: a molecule binds to an enzyme somewhere other than the active site Changes enzyme’s 3-D structure Active site can still bind substrate with the usual affinity But is no longer in the optimal arrangement to catalyze the reactions

Enzyme vocabulary review helper protein molecule that lowers activation energy for specific chemical reactions Substrate molecule that enzymes work on Products what the enzyme helps produce from the reaction Active site part of enzyme that substrate molecule fits into