A LABORATORY PROTOCOL ON THE BIOLOGY  EXPERIMENT CARRIED OUT BY SPANISH  STUDENTS OF ESCUELA PROFESIONAL “LA SALLE” PATERNA (VALENCIA)

Microorganisms: The Yeast.

1.INTRODUCTION

Biology is the science which studies all livings beings and their vital processes; it is of great importance since from it we can understand what happens with livings organisms, from bacteria to larger organisms.

Yeasts are single-celled, microscopic fungi.. They feed on sugars from which they obtain energy in a process called fermentation. Fermentation takes place without the presence of gaseous oxygen.

In this experiment, the results of alcoholic fermentation carried out by yeasts will be verified. As a result of this process, carbon dioxide and ethanol are released, products that are used in the production of bread and alcoholic beverages, such as wine and beer.

2.OBJECTIVE:

Check that biological yeast consists of live microorganisms with a metabolism.

Our hypothesis is that in very hot water the yeast, a being living microorganism, will die and will not carry out fermentation

3.MATERIALS USED

  • Beaker
  • Plastic bags
  • Spatula

4.PRODUCTS USED

  • Yeast
  • Water
  • Sugar

5.PROCESS

Step 1:

Put 125 ml of water into the 250 ml beaker and prepare:

-25 ml of cold water with ice, more or less 4 or 5 degrees centigrade.

-25 ml of warm water at about 35-45 degrees, more or less

-25 ml of hot water, more or less 65-75 degrees

Step 2:

Add 2 gr of sugar to each beaker containing water

Step 3:

The yeast is then added and, with the help of the spatula, it dissolves,

Step 4:

Next, the yeast mixture is placed in three plastic bags and they are tightly tied, taking care not to leave any air inside the bags.

Step 5:

Wait about five minutes, and we can observe how carbon dioxide begins to accumulate in the bags.

6.RESULTS

In the first bag we observe some foam produced by carbon dioxide, although the reaction is slower.

In the second bag, after a few minutes, a large amount of foam is produced by the carbon dioxide

In the third bag, with very hot water , the yeasts die and for that reason no carbon dioxide is produced

7.QUESTIONS

  1. What is fermentation? A biochemical process by which an organic substance is transformed into another, by the action of a ferment.
  2. What is the function of the plastic bag? By closing the plastic bag without leaving air, we allow the yeast to begin to ferment.
  3. What does yeast use for energy? Due to the lack of oxygen it uses the sugar to produce energy.
  4. What products are produced in yeast fermentation? Carbon dioxide

8.CONCLUSION

Thanks to this practice we can demonstrate that yeast is a living being. If this were a simple chemical reaction, the beaker of hot water should show the same results, even faster. However, since the hot water has killed the yeast, the dead microorganisms fall to the bottom.

Our hypothesis was correct.

9. PERSONAL COMMENTS

Yeast is not a chemical product, but is made up of single-celled microorganisms. If they have enough food and a comfortable room temperature they will produce the gas bubbles that make bread fluffy.

REFERENCES

https://www.yeastexperiments.com/yeast-fermentation-experiment/

A Simple and Low Cost Experiment as a Tool to Teach Concepts in Biotechnology