Fermentation And Respiration Essay

Mimi Wong

Biology 5A Lab

Thursdays 9:10a.m-12:00p.m

26 February 2014

Lab 6: Fermentation and Respiration Lab Introduction

Question: How will increasing the number of yeast cells affect the rate of ATP production by the cells (in moles ATP/hr) if the sugar concentration in the experiment is held constant?

Hypothesis: Increasing the number of yeast cells speeds up the rate of ATP production if sugar concentration is held at a constant concentration.

Argument in support of the hypothesis: With an increase in the number of yeast cells, the rate of adenosine triphosphate (ATP) production-in moles of ATP for every hour is affected greatly even when the sugar concentration is constant. When the number of yeast cells grows, more cells are able to use the sugar for energy which causes the ATP production to go up. Fermentation is a catabolic process that makes limited amounts of ATP from glucose molecules (Campbell Biology 9th edition, text pg. G-14). In fermentation, one mole of carbon dioxide produced means that there is one mole of ATP produced (UCR Winter 2014 Bio 05LA Lab Manual: Lab#6, pg.4). Because the sugar concentration of the experiment doesn’t change and is constant, the amount of ATP will increase greatly up to a point.

Experimental Strategy: In this experiment, the yeast being used is called Saccharomyces cerevisiae. This type of yeast follows fermentation which is very unique and can tell how much carbon dioxide is produced by fermentation more accurately compared to cellular respiration. Three test tubes will be filled with a specific volume and concentration of sugar with a certain amount of yeast in each test tube. Two of the three test tubes will have similar concentrations of sugar with different amounts of yeast...

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... a weighed Nalgene bottle and spread in a layer on a side of the bottle and then reweighed. A carbon dioxide sensor will be placed on the bottle opening. Using Lab Quest recorder, data will be collected for five minutes. After, the slope of the carbon dioxide production will be indicated and it will be used to calculate the rate of carbon dioxide was produced. The slope that indicates how much carbon dioxide was produced will be converted to milliliters per hour. Then, moles of gas shall be calculated. For 1 mole of carbon dioxide produced, 5.33 moles of ATP was produced (UCR Winter 2014 Bio 05LA Lab Manual: Lab#6, pg.4). The rate will be used to measure the corn seedlings metabolic rate with yeast cells rate after calculations.

Prediction: If the metabolic rate of a reaction is high compared on a mass specific basis, then the reactant must have been a yeast cell.