Enzymes A special class of proteins that are vital to an organism’s survival. They work by lowering the energy it takes to start a chemical reaction. Biological catalysts that speed up the rates of reaction.

Effect of Enzymes Reaction pathway without enzyme Activation energy Section 2-4 Reaction pathway without enzyme Activation energy without enzyme Reactants Activation energy with enzyme Reaction pathway with enzyme Products

Figure 2-19 Chemical Reactions Section 2-4 Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Reactants Products

Figure 2-19 Chemical Reactions Section 2-4 Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Reactants Products

Enzyme Theories Lock and Key Model Induced Fit Model The substrate fits into the active site SPECIFICALLY. Induced Fit Model The active site changes shape to make the substrate react faster.

Figure 2-21 Enzyme Action Enzyme (hexokinase) Substrates Products Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Enzyme-substrate complex Substrates bind to enzyme Substrates are converted into products

Figure 2-21 Enzyme Action Enzyme (hexokinase) Substrates Products Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Enzyme-substrate complex Substrates bind to enzyme Substrates are converted into products

Figure 2-21 Enzyme Action Enzyme (hexokinase) Substrates Products Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Enzyme-substrate complex Substrates bind to enzyme Substrates are converted into products

Figure 2-21 Enzyme Action Enzyme (hexokinase) Substrates Products Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Enzyme-substrate complex Substrates bind to enzyme Substrates are converted into products

Chemical Reactions Chemical reactions occur when bonds between molecules are broken or formed. Example: Mg+2HCL MgCL2+H2 Note the same # of atoms on each side of the reaction equation. This is referred to as a balanced equation.