Question

You and some of your AP Bio classmates decide to take your yeast respiration lab to the next level and research different ways you could do this experiment. You come across one set up that looks like this:a. What type of metabolism is the yeast doing in this experimental setup? *paraffin is a wax)* Explain how you know.b. You want to mimic bread making, so you decide to put your yeast in a mixture of water and flour instead of a sugar mixture. Flour contains gluten which when can form disulfide bridges in solution. Based on this information, what is gluten and describe how you know?c. You repeat the experiment with lipids added to the mix. You notice that the rates of metabolism look as follows. Interpret the results and what fats do to yeast metabolic rate.

Answer 1

Yeast performs anaerobic respiration (fermentation) in the absence of oxygen, producing ethanol and CO₂. Gluten is a protein that forms disulfide bridges, giving dough elasticity. The effect of lipids on yeast metabolism varies, potentially slowing down or speeding up metabolic rates depending on conditions and the yeast's metabolic pathways.

Step-by-step explanation:

Yeast Metabolism in Various Experimental Setups

a. In the described experimental setup, the yeast is likely performing anaerobic respiration, specifically fermentation. The wax (paraffin) barrier suggests an absence of free oxygen in the environment, and since yeasts are capable of fermentative metabolism under such conditions, they would ferment sugars, producing ethanol and CO₂. This setup mimics conditions where yeast's aerobic respiration is not possible.

b. Gluten is a protein composite found in wheat and related grains. It is composed of gliadin and glutenin, which are capable of forming disulfide bridges when hydrated, giving dough its elastic property. These bridges form between cysteine residues within the gluten proteins, stabilizing the dough's structure.

c. The addition of lipids to yeast metabolism experiments can alter the metabolic rate of yeast. If the observed rates of metabolism decrease, it may suggest that lipids are not as readily metabolized by yeast as simple sugars are, slowing down the rate of fermentation or respiration. Conversely, if rates increase, it could indicate that lipids are providing an alternative source of energy, possibly through beta-oxidation if oxygen is present, affecting the overall metabolic rate.