Cellular Respiration (Monica Magdaleno)

Title: Can yeast inflate a balloon? An exploration of cellular respiration

Principle(s) Investigated: Energy conservation of catabolic pathways, Enzyme catalyzed chemical reactions that generate energy use oxygen

Standards : 7.1d Students know that mitochondria liberate energy for the work that cells do and that chloroplasts capture sunlight energy for photosynthesis.

7.7c Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.

Materials: Active dry yeast, warm water, sugar, bottle, balloon, funnel (we used paper funnels), tablespoon, teaspoon

Procedure: 1. Get a balloon. Stretch it out and blow it up to loosen it up. Let the air out and place it aside.

2. Add some warm water to the bottom of an empty bottle.

3. Place a funnel in the mouth of the bottle.

4. Measure out 2 teaspoons of active dry yeast. Pour it in the bottle through the funnel.

5. Swirl it around to activate the yeast.

6. Measure out 1/2 teaspoon of sugar. Use the funnel to pour it in.

7. Take the funnel out and swirl the bottle around again.

8. Place the opening of the balloon over the mouth of the bottle.

9. Leave in a warm place for about 15 minutes.

Student prior knowledge: Students should know about prokaryotic and eukaryotic cells, the mitochondria, and cellular respiration

Explanation: Yeast is a living organism. It is a single celled microscopic fungus. In this stage it is dormant. This means it is not active now, but can become active. The yeast will become activated when it is mixed with warm water. If it does not activate, then it has died. Students can inspect the yeast and see if it looks like a living organism. They will add water, then the yeast to the bottle and swirl it around. At this time, I would ask students to observe the yeast at this stage to see if it has come alive (or if it is alive). I would also ask them to smell it to see if the smell is familiar to any of them. It may remind them of bread.

Now that the yeast has become active, it needs to eat. This is why we add sugar. The yeast will eat the sugar and metabolize it to get energy. Just like humans, yeast can metabolize sugar in two ways: aerobic and anaerobic). Aerobic is with oxygen and anaerobic is without oxygen. The reaction with oxygen yields more energy. The yeast will convert the sugar during cellular respiration and expel carbon dioxide and alcohol. The heat of the warm water speeds up the reaction. At this time students will add the balloon to the top of the bottle. The yeast will start to bubble and rise, the carbon dioxide gas will be trapped by the balloon and inflate. The reaction usually takes about 15 to 20 minutes.

Below is the equation for cellular respiration:

Glucose and oxygen are taken in and carbon dioxide, water and energy are expelled. The energy is used to fuel the cell's many activities. Much of this energy keeps the body warm.

Questions & Answers: 1. Would this reaction still take place in cold water? Yes, the reaction will still take place but it will be much slower. The heat helps act like a catalyst.

2. What would happen to an animal if all its mitochondria disappeared? Without mitochondria, the cell will not be able to go through cellular respiration and create energy for necessary processes. Without this energy the organism will die.

3. How are photosynthesis and cellular respiration related? Photosynthesis is the way plants metabolize

Applications to Everyday Life:

1. This process happens when making bread. This is why there are holes in the bread (from the bubbles of carbon dioxide). The heat from baking bread gets so high, the yeast dies and the alcohol evaporates.

2. Cellular respiration takes place in humans and many other organisms. In prokaryotes, the process takes place in the cell membrane. In eukaryotes, the process takes place in the motichondria.

3. Cellular respiration without oxygen is called fermentation. This process occurs when making alcohol such as wine or beer.

Photographs: Include a photograph of you or students performing the experiment/demonstration, and a close-up, easy to interpret photograph of the activity --these can be included later.

Videos:

Yeast Alive! video by Scientific American:

http://m.youtube.com/watch?v=3aZrkdzrd04&desktop_uri=%2Fwatch%3Fv%3D3aZrkdzrd04

Cellular Respiration Song Video from a Biology teacher putting the steps of Cell respiration to the Black Eyed Peas song, I Got A Feeling:

http://m.youtube.com/watch?v=3aZrkdzrd04&desktop_uri=%2Fwatch%3Fv%3D3aZrkdzrd04