Catalase Lab and Enzymes

Enzyme Lab 1

 SWBAT explain the effect of temperature and pH on enzyme activity

Multiple Choice

A catalyst made of protein that speeds up chemical reactions

• enzyme

• denature

• pH

• substrate

Multiple Choice

The molecule/substance on which the enzyme works

• optimal temperature

• denaturing

• pH

• substrate

Multiple Choice

the location on an enzyme where the enzyme and substrate combine

• substrate

• denature

• active site

• pH

Multiple Choice

The temperature at which a specific enzyme works best; enzyme activity is at its highest

• optimal temperature

• pH

• active site

• substrate

Part 1: Launch

We have been learning about enzymes, protein catalysts that speed up chemical reactions that occur in all living things. A potato is considered a living thing because it comes from a plant; in all potatoes, you can find the enzyme catalase. Today, we will be test the effect of temperature and pH on the reaction rate of catalase. We mentioned pH a couple days ago when we first talked about enzymes. Before we begin the lab, let’s learn a little more about the pH scale is and how to read it. 

Multiple Choice

A scale of how acidic or alkaline a substance is

• active site

• pH

• enzyme

• denature

Multiple Choice

Process in which enzymes change shape due to extremely high temperatures

• enzyme

• denature

• substrate

• active site

Part 2: Pre- Lab Check

Every liquid you see will probably have either acidic or basic traits. So what makes an acid or a base? A chemist named Svante Arrhenius came up with a way to define acids and bases in 1887. He saw that when you put molecules into water, sometimes they break down and release an H+ (hydrogen) ion. At other times, you find the release of an OH- (hydroxide) ion. When a hydrogen ion is released, the solution becomes acidic. When a hydroxide ion is released, the solution becomes basic. 

Part 2: Pre-Lab Check

Scientists use something called the pH scale to measure how acidic or basic a liquid is. The scale measures values from 0 all the way up to 14. Acids are found between 0 and 6. Bases are from 8 to 14. Substances with a pH of 7, like water, are considered neutral. 

At very low pH’s (0-1) we consider the substance to be a strong acid. Strong acids can be very dangerous, especially if exposed to your skin or digested. At very high pH’s, we consider the substance to be a strong base. Similarly to acids, a strong base can be very dangerous to living organisms.

Open Ended

Which substance is the most acidic according to this scale? How do you know?

Open Ended

Orange juice has a pH of 3. Is it acidic or basic?

Open Ended

Bleach has a pH of 13. Is it acidic or basic?

Open Ended

The enzyme galactosidase is found in most tomatoes. State how the activity of galactosidase will most likely change if it was moved into soapy water.

Open Ended

Which substance is the most basic according to the scale above? Explain.

Open Ended

Which substance is neither acidic nor basic? Why?

Part 3: Background

An enzyme is a protein that speeds up or slows down a specific chemical reaction in an organism. A good rule of thumb is to remember that enzyme names end in “-ase”. This will help in identifying enzymes in further readings. Generally, enzymes are catalysts.

Part 3: Background cont...

Hydrogen peroxide is a toxic chemical that is produced in many organisms during metabolism. Organisms must get rid of this toxin to survive. One reaction turns the hydrogen peroxide into water and oxygen. The enzyme that helps with this reaction is called catalase. This is found in both plants and animals. In this lab we will use potatoes as our catalase source. The reaction equation is:

Part 4: Purpose

The purpose of this experiment is to determine what effect pH has on the amount of catalase activity that takes place. To test this, you will set up 3 test tubes, each containing a liquid of a different pH: baking soda (pH = 8.5), water (pH = 7) and lemon juice (pH = 2.0). You will record the height of the foam that is produced in millimeters. 

Quick check:

In this lab, bubbles of gas will be produced. What is inside those bubbles of gas?