catalase lab intro - norwellschools.org · • purpose of lab: how is catalase enzyme activity...

Catalase Lab Intro

Check your introduction• Enzyme = Catalase (found in most plants

and animals)• Substrate = H2O2

• Chemical Reaction:

Check your introduction• Why do we have catalase?

Check your introduction• Why do we have catalase?

– Mitochondrial reactions generate H2O2.

Check your introduction• Why do we have catalase?

– Mitochondrial reactions generate H2O2.• By-product of producing energy.• Toxic to cells, so must be broken down.

Check your introduction• Why do we have catalase?

– Mitochondrial reactions generate H2O2.• By-product of producing energy.• Toxic to cells, so must be broken down.

• Why are we using beef liver??

Check your introduction• Why do we have catalase?

– Mitochondrial reactions generate H2O2.• By-product of producing energy.• Toxic to cells, so must be broken down.

• Why are we using beef liver??– Organ that removes toxins.– Contains A LOT of mitochondria.

Check your introduction• Purpose of lab: How is catalase enzyme

activity affected by concentration, temperature, and pH?– Under which condition does catalase work

best???

Hypothesis• Determine your condition. • Create a hypothesis that relates to your

condition. – If…– Then…– Because…

Hypothesis• Determine your condition. • Create a hypothesis that relates to your

condition. – If…– Then…– Because…

• Methods VERY important!

Conduct your experiment• Design--You must show me this before you

begin.

Conduct your experiment• Design--You must show me this before you

begin.– Controlled variables: What will be the same in each

tube?

Conduct your experiment• Design--You must show me this before you

begin.– Controlled variables: What will be the same in each

tube?• Time before measuring; Amt of enzyme & substrate.

Conduct your experiment• Design--You must show me this before you

begin.– Controlled variables: What will be the same in each

tube?• Time before measuring; Amt of enzyme & substrate.

– Independent variable: What will you change and how?

• Don’t know yet.

Conduct your experiment• Design--You must show me this before you

begin.– Dependent variable: What will you measure and

how?

Conduct your experiment• Design--You must show me this before you

begin.– Dependent variable: What will you measure and

how?• Catalase breaks down H2O2 Bubbles!

Conduct your experiment• Design--You must show me this before you

begin.– Dependent variable: What will you measure and

how?• Catalase breaks down H2O2 Bubbles!• Measure rate of production of bubbles in test tube after

H2O2 is added.

Conduct your experiment• Design--You must show me this before you

begin.– Order of addition:

• Enzyme first (bottom of tube).

• Independent variable next.

• Add H2O2 last and measure gas production.

Ways to vary condition?

• Acid/base dropper bottles…how could you vary the pH within your five tubes (and be able to make a line graph)?

• How could you use the freezer or hot bath to get various temperature enzymes and create a line graph?

• How can you change concentration of enzyme or substrate?

• Need FIVE data points for good analysis.

How much enzyme and substrate?

• For enzyme there is a disposable plastic pipette. One pipette is about 1 ml broken into .25 ml gradations

• For substrate there is a measured pipetter. Watch the demo of how it works? How much substrate do you want to put in your tubes? Does it matter?

• Total amount of enzyme and substrate should not exceed 2 ml or your tubes may overflow. Test with your control first!!!

Begin

• BRIEFLY discuss hypothesis.• Design experiment.• Have design checked!!!• Complete lab in lab period,

carefully documenting data and directions.

• Over Week--draft ideas for introduction, hypothesis, and methods; discuss data/graphing!!!