UNIT 2 Chemistry for Biology ENZYMES

A chemical reaction is the process of a chemical change in which substances change into DIFFERENT substances. Reactant(s) Product(s) starch sugar

Enzymes Enzymes are globular proteins that living things make which speed up (catalyze) the rate of a chemical reaction. They remain unchanged by the reaction!

Enzyme-Substrate Complex Enzyme

5Enzymes Are specific for what they work on Are specific for what they work on Are Reusable Are Reusable End in –ase End in –ase-Sucrase-Lactase-Maltase

Enzymes They are specific to certain molecules, which we call substrates They are specific to certain molecules, which we call substrates SubstrateEnzyme LactoseLactase Hydrogen PeroxideCatalase StarchAmylase ProteinPepsin

7 How do enzymes Work? Enzymes work by lowering the activation energy Analogies: Job-Hunter, Cell Phone Activation, matchmaker

How enzymes work Active Site – the site on the enzyme where the substrate binds

Fig. 5.6 How enzymes work Enzyme-substrate complex– the enzyme and substrate together

Fig. 5.6 How enzymes work Product is formed. The enzymes remain unchanged!

Fig. 5.7 The catalytic cycle of an enzyme 1 The substrate, sucrose, consists of glucose and fructose bonded together. Bond Enzyme Active site The substrate binds to the enzyme, forming an enzyme-substrate complex. 2 H2OH2O The binding of the substrate and enzyme places stress on the glucose-fructose bond, and the bond breaks. 3 Glucose Fructose Products are released, and the enzyme is free to bind other substrates. 4

Lock & Key Hypothesis

Induced-Fit Model

Enzymes work best under certain conditions e.g. temperature, pH

The Effect of Temperature

The Effect of pH

The Effect of substrate concentration

Denaturation A structural change in a protein that results in the loss (usually permanently) of its biological properties. A structural change in a protein that results in the loss (usually permanently) of its biological properties. Heat and pH usually cause denaturation. Heat and pH usually cause denaturation.

Enzyme Demo Enzyme Demo