Enzymes

Which property of water prevents living organisms from being frozen into a pond? A High heat of vaporization B High specific heat C Cohesion of water molecules D Ice is less dense than liquid water

What Are Enzymes? Most enzymes are Proteins Act as Catalyst to accelerate a reaction Not permanently changed in the process

Enzymes Are specific for what they will catalyze Are Reusable End in –ase -Sucrase -Lactase -Maltase

Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Enzyme Joins Substrate

Active Site A active site of an enzyme molecule which binds to the substrate. Active Site Enzyme Substrate

Induced Fit A change in the shape of an enzyme’s active site Induced by the substrate

Induced Fit A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). Induced by the substrate. Enzyme Active Site substrate induced fit

Checkpoint! What is a catalyst? What is the name for the substance in which the enzyme acts on? Where does the substrate bind to the enzyme?

A water strider (insect) can skate along the top of a pond because: A Hydrogen bonds result in cohesion B Covalent bonds result in cohesion C Water’s ability to maintain homeostasis D Capillary action allows for adhesion

How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy

Enzymes Without Enzyme With Enzyme Free Energy Progress of the reaction Reactants Products Free energy of activation

How do enzymes work? Enzymes can break down one reactant to form more than one product OR Enzymes can bind more than one reactant to form one product

True or false: Checkpoint! Enzymes speed up chemical reactions by increasing the activation energy of the reaction

Water has a high specific heat. What does this mean? A It takes a lot of heat to form cohesion B It takes a high temperature to cause evaporation C Water’s temperature changes easily D It takes a lot of energy to raise or lower the temperature of water

What Affects Enzyme Activity? Three factors: 1. Environmental Conditions 2. Cofactors and Coenzymes 3. Enzyme Inhibitors

1. Environmental Conditions 1. Extreme Temperatures are the most dangerous 2. pH (most like 6 - 8 pH near neutral) 3. Ionic concentration (salt ions)

2. Cofactors and Coenzymes Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes need for proper enzymatic activity. Example: Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen.

Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Substrate Competitive inhibitor

Inhibitors b. Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme Noncompetitive Inhibitor Substrate active site altered

Which of the following properties of water refers to two molecules of water stuck together by a hydrogen bond? adhesion cohesion surface tension capillary action