Energy In Reactions

• Energy is released or absorbed whenever chemical bonds are formed or broken.

• Because chemical reactions involve breaking and forming of bonds, they involve changes in energy.

Catalyst

• A catalyst is a substance that speeds up the rate of a chemical reaction.

• Catalyst work by lowering reaction’s activation energy.

Notice that without the enzyme it takes a lot more energy for the reaction to occur. By lowering the

activation energy you speed up the reaction.

Enzymes

• Enzymes are proteins that act as biological catalysts.

• Cells use enzymes to speed up chemical reactions that take place in cells.

• Enzyme speed up reactions by lowering the activation energies.

• Because a particular enzyme catalyzes only one reaction, there are thousands of different enzymes in a cell catalyzing thousands of different chemical reactions

Note:

Enzymes end in

aseCatalase

Amalase

Enzymes

• Enzymes provide a site where reactants can be brought together to react.

• Such a site reduces the energy needed for a reaction to occur.

All enzymes have an active site, where substrates are attracted to.

• Enzymes are used over and over again.

Substrate

• The substance changed or acted upon by an enzyme is the substrate.

The Enzyme Substrate complex

• When enzymes function the active site interacts with the substrate.

• The active site shape matches the substrates shape.

• Once the substrate and active site meet a change in shape of the active site causes a stress that changes the substrate and produces an end product.

Which one will fit ?

• http://www.lewport.wnyric.org/jwanamaker/animations/Enzyme%20activity.html

The factors that affect enzyme activity are

• pH

• Temperature

• Amount of substrate

Affects of temperature on an enzyme

• If temp to high or to low the enzyme will not fit. No reaction will occur.

How pH affects an enzyme

• If the pH is to high or low the enzyme will not work, because its shape will change.

pH

• All enzymes have an optimum pH that they function best at.

• If the pH is to low or to high the enzyme will work slow because the change in pH changes the shape of the enzyme making it harder for the substrate to fit in.

Analyze the graph at what ph does Chymotrypsin function best?

Temperature• Enzymes function best at

an optimum temperature depending on the type of enzyme it is.

• As the temperature rises the enzyme and substrate molecules move quicker causing more collisions to occur, there for creating more products.

• If you make the temperature to high you will destroy the protein (denature) it.

What is the optimal temp for this enzyme

Amount Of Substrate Present

• At low substrate concentrations, collisions between enzymes and substrate molecules are rare and reactions are slow.

• As the amount of substrates increase so does the collisions between enzymes and substrates.

• This continues until the enzymes are saturated.