Cells live byMolecular Actions

Laboratory Investigation into how molecules carry out Cell

life processes

Cells

Molecules

H2O2 2H2O + O2

Brainstorm

• What changes during a chemical reaction?• What stays the same during a chemical

reaction?• What is a catalyst? Examples?

Enzyme = Biological Catalyst

• Catalase• active site

Let’s look at one Molecule in Cells

• Task 1: Observe Yeast Cells under the microscope.

• Task 2: Observe Catalase breakdown a cellular waste molecule (H2O2); add Yeast/water suspension to Hydrogen Peroxide.

• Task 3: Carry out a plan to gather evidence about how Catalase works.

Task 1

• Place one drop of yeast suspension on a microscope slide.

• Place cover slip over the top• Observe first at low power, move to higher

mag.• Record and label what you see in your

notebook (sketch, mag, description)

Task 2

• Place 3 mL of H2O2 into a test tube.• Place 1 mL of yeast suspension (Catalase) into

the test tube.• Record your observations.• What would happen if you doubled the

amount of H2O2? Catalase?– Record what you do; Record your results.

• Is Catalase reusable? How could you test this?– Record what you do; Record your results.

Task 3 Considerations• Consider one of these factors:– Salinity (salt concentration) – Temperature – pH (we have 0.1 M HCl and 0.1 M NaOH)

• What will make for good scientific evidence?• What change will you be looking for to show the

activity of catalase?• How much of each material will you use? Why?• Record what you do and what you observe. This

is your evidence.