Section 2.5 Enzymes

Word Splash Enzyme Active Site Biological Catalyst Activation Energy Substrate Denatured Lock and Key Reusable

Key Concept Enzymes are proteins that speed up chemical rxns in living cells by lowering the amount of activation energy (EA) needed to get them started proteins catalyst

Chemical Reactions require E Energy is needed to start a chemical reaction. This energy is used to break the bonds between atoms in the reactant molecules so they are free to recombine in new ways The amount of energy needed is called activation energy (Ea). Weakening bonds Lowering

Function of Enzymes Enzymes make rxns go faster by reducing the amount of activation energy needed for the reaction to start

Activation Energy What’s needed to get the rock rolling down the hill on its own? ENERGY INPUT

Enzymes are Biological Catalysts A catalyst speeds up the rate of the reaction by reducing the amount of activation energy needed to start the reaction. Because enzymes have the job of catalysts in living things they’re called biological catalysts.

How Enzymes Work Enzymes are protein molecules.

Enzyme Shape determines Function Each enzyme has a unique shape with a special area called an active site

Enzyme – Substrate Complex One or more molecules called substrates bond to the enzyme’s active site. Together they form an enzyme –substrate complex.

Lock and Key Theory An enzyme’s specific shape allows it to fit with only one substrate like a lock and key.

Enzyme – Substrate Complex Once the enzyme and substrate combine a shape change occurs.

Enzymes help reactions go faster The shape change provides the energy needed to break or form bonds in the substrate so that new molecules , called products, can be formed . They are then released from the active site.

An enzyme flick Let the show begin....

Enzymes Enzymes are reusable – they can be used over and over again to catalyze / speed up a specific reaction.

Enzymes are Unique Each enzyme is unique in its shape and catalytic activity. Different environmental factors affect how well an enzyme works. Environmental conditions that cause each type of enzyme to work its best – Optimal condition

Factors that Affect Enzyme Activity pH Temperature Substrate Concentration-amount of substrate molecules Enzyme Concentration- amount of available enzyme

Optimal Conditions The environmental conditions that cause each type of enzyme to work its best are called – optimal level. For example, 98.6 ° is the optimal temperature for enzymes to work in the human body.

Enzyme Activity Graphs

Affect of Substrate Concentration https://www.youtube.com/watch?v=HnbNcQlzV-4

Enzymes can be Denatured Certain conditions can cause an enzyme’s shape to change. If an enzyme’s shape changes it cannot do its job. This is called denatured

Many diseases are caused by a missing or defective enzyme Many diseases are caused by a missing or defective enzyme. Lactose intolerance – missing lactase______________ __________________________________________ Phenylketonuria (PKU) – missing phenylketonurase.

Enzyme Activity Graph with zones of activity/inactivity

Quick Facts about Enzymes Enzymes are protein molecules Enzymes function to make reactions go faster Are reusable There are about 2000 different enzymes in each one of your cells Each enzyme fits with only ________ substrate molecule Names usually end in -ase specific reusable ase

General Types of Enzymes Amylases – break starch to glucose Lipases – break lipids to fatty acids Proteases – break proteins to amino acids Nucleases – break nucleic acids DNA and RNA to nucleotides

Factors that affect Enzyme Action

How do enzymes work? Each enzyme has a unique 3-D shape, including a surface groove called an ACTIVE SITE. One or more molecules called SUBSTRATES chemically bond to the enzyme’s active site. When joined they are called an ENZYME-SUBSTRATE COMPLEX Changes in how the atoms are bonded occur resulting in new molecules being made called PRODUCTS . Products are then released from the active site. Active site Substrate Product