enzymes

Enzymes are Proteins• Many of our genes code

directly for enzymes• Estimated to be about

75,000 different types in the human body

Enzymes

Do…. Do Not…

• Speed up chemical reactions

• Allow reactions to occur with less energy input

• Provide energy for the reaction

• End up altered or used up or in the product

• Change the net effect of the reaction (the products are the same with or without an enzyme)

So What Do Enzymes Do? • They allow bonds to be

broken at lower temperatures

• Thus they lower the activation energy

• So reactions can happen more easily with less input of energy (at lower temps)

• *this is why we are not on fire!

Enzyme Terminology

• Substrate = reactant• Active site =

place on enzyme where the substrate can bind

Enzymes are Specific!• Only substrates that “match” the

active site can be catalyzed• Like a lock and key

• http://www.youtube.com/watch?v=XTUm-75-PL4

Fun with Enzymes: The Enzyme Catalysis Lab

• You will be testing how different factors affect the rate of an enzyme-catalyzed reaction

• http://www.youtube.com/watch?v=4FWa6frjxl4

You will spend the rest of class today doing the pre-lab with your table. If you get to the procedure you will begin that alone and finish for HW

Your Experiment• Should test how 1 factor affects the rate of

hydrogen peroxide decomposition

• Should include 3 experimental trials and a control trial

• Should be conducted in a single block period (90 min) on A 10/31 or B 11/4

• The standard reaction is about 1ml of peroxide with 1ml of catalase solution.

You Are Writing Your Own Procedure

• Needs to be thorough!• Nothing is too small to put in

procedures –i.e. put on glasses, rinse cups

Your Procedure Con.• Set up your entire experiment at once– Make all of the catalase you need at once, put it into

all the test tubes at once etc.• Anything you will need to do should be in the procedure– I.e. rinsing cups, measuring amounts of water, how

long you let the reaction run etc.• Anything you will need to use should be in the procedure– i.e. graduated cylinder, scale etc.

Safety

• No open flames• Goggles must be worn• Immediately report any broken

glassware!

Homework• WP: 6.4- to review what I just presented • Write a procedure for your lab