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In Future Issues...

IRP Research Roundup

Research Festival and CC's 50th

Phoenix Tales

Alan J. Cann, Department of Microbiology & Immunology, University of Leicester, U.K.

Saccharomyces cerevisiae

Kids' Catalyst

Just looking at this stuff, you’d never think it could be used to make bread, or wine, or pizza. But you’ll soon see that you can make this dull, dry sandpile just bubble over with enthusiasm!

First, it might be a good idea to get a grown-up to help you gather the ingredients and equipment you’ll need (and don’t be surprised if the grown-up gets curious and wants to stick around to see what happens).

You will need:

A package of dry active yeast

Four small glasses (cordial size would be good, but test tubes would be even better)

A packet of sugar

Warm and cold tap water

Your sense of what is warm and cold is just fine. (You might also write down your observations, glance at the clock every now and then, and use some wooden chopsticks to stir.)

Now let’s get started.

So that you remember what to do and what is in each glass container, label the four glasses (with a Post-It) with the following: 1) Yeast-warm-sugar. 2) Yeast-cold-sugar. 3) Yeast-warm. 4)Yeast-cold.

Step 1: Open the package of yeast and pour it on a plate. There’s not much there at all—and we’re going to divide that little bit into quarters, too! (Not much? We’ll see.) Shake the dry yeast so it covers the plate, then divide it into quarters (an index card is a good tool for this). Put each quarter in its own glass.

Step 2: Into the two glasses that are marked to have sugar, sprinkle enough sugar to cover the surface of the yeast—a healthy "pinch."

Step 3: Now for warm and cold. Fill a separate container with warm tap water that feels like bathwater and another separate container with cold tap water that feels like a cold soda. Then pour the warm water into the two yeast glasses that are marked for warm, and pour the cold water into the two yeast glasses that are marked for cold (look at the label to make sure, and pour the water almost to the top).

Step 4: Stir. Use separate stirrers for the glasses with and without sugar.

Step 5: Wait and wonder—but you won’t have to wait long at all to see something happening.

So, what is it that makes dry, dull yeast wake up and bubble over? When you decide what that is, see if you can get all four yeast samples to behave like that.

—Jennifer White, NIGMS

For more information about yeast (and action videos), see this website.