Yeast Pre-Lab

Yeasts’ capability of undergoing ethanol fermentation, its ability to ferment other sugars and artificial sweeteners, and how lactase influences yeasts ability to use lactose as a food source
Kristina Naydenova
Father Michael Goetz

Purpose

Part A: To investigate whether yeast has the ability to ferment glucose to produce carbon dioxide gas and ethanol.

Part B: To investigate whether yeast has the ability to ferment other sugars and artificial sweeteners and how lactase influences their ability to use lactose as a food source.

Question

Part A: Does yeast have the ability of undergoing ethanol fermentation?

Part B: Does yeast have the ability to ferment other sugars and artificial sweeteners? Does lactase influence the ability of yeast to use lactose as a food source?

Hypothesis

Part A: If yeast produces carbon dioxide gas (the solution will turn cloudy due to carbon dioxide presence) and ethanol after fermenting glucose then it has the ability to undergo ethanol fermentation because ethanol fermentations reactants consist of glucose and the products consist of carbon dioxide gas and ethanol.

Part B: If yeast has the ability to ferment other sugars and artificial sweeteners then the products of the solution will consist of carbon dioxide gas and ethanol because the products of ethanol fermentation are carbon dioxide gas and ethanol. If lactase influences the ability of yeast to use lactose as a food source then the yeast will be able to use lactose to produce carbon dioxide gas and ethanol because the yeast will be capable of breaking down lactose into glucose and galactose.

Materials

* Safety goggles | * Lab apron | * 4 flasks (100 mL) and 1 stopper | * Wax pencil (for making test tubes) | * Ruler | * 6 large beakers (400 mL) | * Thermometer | * Stopwatch | * 50 mL glucose suspension (10%) | * 50 mL yeast suspension (I package per 100 mL of water) | * Cotton batting | * Limewater