You combine 0.2 g of yeast, 0.2 g of sucrose and 10 mL of...

You combine $0.2 \mathrm{g}$ of yeast, $0.2 \mathrm{g}$ of sucrose and $10 \mathrm{mL}$ of water place the mixture inside an uninflated balloon, then tie off the opening of the balloon. (a) Explain what you would observe over the next hour. (b) What would you observe if you added iodoacetate to the mixture? (c) What would you observe if the mixture contained lactose rather than sucrose?

You combine $0.2 \mathrm{g}$ of yeast, $0.2 \mathrm{g}$ of sucrose and $10 \mathrm{mL}$ of water place the mixture inside an uninflated balloon, then tie off the opening of the balloon.
(a) Explain what you would observe over the next hour.
(b) What would you observe if you added iodoacetate to the mixture?
(c) What would you observe if the mixture contained lactose rather than sucrose?

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Key Concepts

Fermentation

Fermentation is a metabolic process in which microorganisms like yeast convert sugars into energy along with byproducts such as alcohol and carbon dioxide. In the context of the experiment, yeast fermenting sucrose will produce carbon dioxide, which inflates the balloon over time due to gas build-up in the closed system.

Enzymatic Inhibition (Glycolysis Inhibition by Iodoacetate)

Iodoacetate acts as an inhibitor of glycolysis by targeting enzymes like glyceraldehyde-3-phosphate dehydrogenase. This inhibition prevents the yeast from efficiently breaking down sugars to produce energy, thereby reducing or stopping carbon dioxide production. The reduction in gas generation would be observable as little to no balloon inflation compared to the normal fermentation process.

Substrate Specificity of Yeast Metabolism

Yeast typically ferment sugars such as glucose, fructose, and sucrose efficiently; however, they cannot readily metabolize lactose due to the lack of necessary enzymes, such as ?-galactosidase. If lactose is provided as the substrate instead of sucrose, the yeast’s metabolism would be compromised, leading to minimal fermentation, little to no production of carbon dioxide, and therefore, minimal balloon inflation.

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