A comparison of the respiration of yeast in different sugar substrates.

The experiment was conducted to determine the impact different yeast amounts had on yeast fermentation. It was hypothesized that the more yeast added the more CO2 would be produced. The carbon dioxide production was measured in the fermentation of yeast with solution of no yeast in test tube 1, 1mL yeast in test tube 2, and 3mL of yeast in test tube 3 over a period of twenty minutes. All of the yeast amounts produced CO2, but test tube 3 was the most efficient of the three.

Yeast will aim to respire aerobically, as higher yields of ATP can be acquired, however in certain environments it is able to respire anaerobically. Like most other living organisms, yeast metabolic activity is controlled by enzyme activity. Yeast, after activation creates carbon dioxide and ethyl alcohol by secreting the enzyme zymase, which is a complex of 12 enzymes, in the yeast which acts on simple sugars such as glucose. Enzymes are biological catalysts; they are designed to help speed up the rate of many reactions without actually taking part in the reaction themselves, therefore being reusable.

The purpose of this investigation is to test the effect of different sugar sources on yeast respiration.

Respiration is a chemical process by which organic compounds release energy. There are two types of respiration reactions that cells use to provide themselves with energy: aerobic and anaerobic (fermentation). (Chemistry for Biologists: Respiration. 2015) Both processes are similar within the initial steps of the reaction- beginning with glycolysis. However, in fermentation instead of the pyruvic acid being converted to acetyl coenzyme A, it’s converted into both ethanol and carbon dioxide in yeast and some plants and lactic acid in animal cells. Another distinct difference between the two processes is that anaerobic respiration uses oxygen

Yeast is a fungus that can generate glucose into energy without using any oxygen molecules. We tested the fermenting ability of yeast from two different carbon sources: glucose and aspartame. We hypothesized that yeast is unable to use the carbon sources of aspartame. To do this, we decided to use both carbon sources in the same concentration. Each carbon source was mixed with the same amount of yeast solution. The experiment group of 5.5 mM aspartame solution was compared with the control group of 5.5mM glucose solution. We recorded the rate of fermentation for glucose and aspartame in the Vernier Lab Quest. The fermentation rate of aspartame is a negative number, and glucose is a positive number. Our results show that yeast was unable to ferment aspartame as yeast fermented glucose. The results indicate that aspartame has no effect on yeast fermentation rate because yeast do not catabolize aspartame because it does not have the appropriate enzymes to break it down.

Cellular respiration is the series of metabolic process by which living cells produce energy through the oxidation of organic substances. Cellular respiration takes place in the mitochondria. Fermentation is the process by which complex organic compounds such as glucose, are broken down by the action of enzymes into simpler compounds without the use of oxygen. The significance of these pathways for organisms is to allow for an organism to be able to generate ATP. Some organism that undergo cellular respiration are bacteria and fungi. Some organism that undergo fermentation are yeast and muscle cells. In cellular respiration, glucose is oxidized and releases energy. In cellular respiration, glucose produces ATP and 3-carbon molecules of pyruvate. The pyruvate is then further broken down in the mitochondria where it becomes oxidized and releases CO2 (Upadhyaya 2014). In the fermentation process oxygen does not play a part. This process converts glucose into pyruvate and produces ATP. From there pyruvate breaks down into CO2 and acetaldehyde (Upadhyaya 2014) Monosaccharides are known as simple sugars and their main function is being the source of energy for organisms. Disaccharides are two monosaccharides joined by a covalent bond and their primary function is to provide food to monosaccharides. Some disaccharides

We hypothesize that sucrose would have the highest respiration rate due to the fact that it is a disaccharide containing glucose and fructose, a combination of two sugar sources. The more sugar the S. cerevisiae is fed, the more CO₂ will be produced.

In this lab we tried to find what fuels yeast could metabolize and what the yields of the carbon dioxide gas that were produced from the different sugars used. We used 6 different yeast and sugar mixtures. The different yeast and sugar mixtures we used were control, glucose, sucrose, fructose, starch, and saccharin. The results for the 6 different results are presented in Tables 1-6 and Graph 1. Graph 1 is a graph of all the information in Tables 1-6. Each Table and graph is labeled approximately.

This lab investigates the effects of Sucrose concentration on cell respiration in yeast. Yeast produces ethyl alcohol and CO2 as a byproduct of anaerobic cellular respiration, so we measured the rate of cellular respiration by the amount of CO2

The hypothesis stats that as the sucrose concentration is increased, rate of respiration will increase and therefore the CO2 production of yeast cells will rise. Sucrose is a disaccharide composed of the monosaccharaides glucose and fructose. Glucose is a reactant in anaerobic cell respiration. In the absence of oxygen, glucose will react with the yeast producing ethanol and CO2.

Hypothesis: The yeast will have a greater rate of respiration for the natural sugars specifically the glucose and lower rate of respiration for the unnatural sugars

Table 1: Table of Results Showing the Effect of Yeast Mass on the Rate of Yeast-Facilitated Fermentation of Glucose

Sugars are vital to all living organisms. The eukaryotic fungi, yeast, have the ability to use some, but not all sugars as a food source by metabolizing sugar in two ways, aerobically, with the aid of oxygen, or anaerobically, without oxygen. The decomposition reaction that takes place when yeast breaks down the hydrocarbon molecules is called cell respiration. As the aerobic respiration breaks down glucose to form viable ATP, oxygen gas is consumed and carbon dioxide is produced. This lab focuses on studying the rate of cellular respiration of saccharomyces cerevisiae, baker’s yeast, in an aerobic environment with glucose, sucrose, lactose, artificial sweetener, and water as a negative control. A CO2

Whereas the large molecule food (Sucrose) will take longer to break down because of its large molecules, this will waste the energy of the yeast as it has to break down the large molecules into smaller molecules before it can use them. This means that the sucrose is not as efficient as the glucose at providing the yeast with a better medium by which it will produce a faster rate of respiration. Theory:

The term ‘’Carbohydrates’’ is defined as the carbon compounds which contains hydroxyl groups in large quantities (King, 2013). Carbohydrates are those organic compounds which have the empirical formula CnH2nOn, or (CH2O)n (Fromm 1997). Carbohydrates are one of the four types of organic compounds in living cells that are produces during photosynthesis and are the important source of energy in both plants and animals (Ahmed 2014). They are built from monosaccharides. These monosacchradies are the small molecules that consists of three to nine carbon atoms and differ in size and in the stereochemical configuration at one or more carbon centers. The simplest carbohydrates also contain either an aldehyde or ketone compounds (freeman 2002). Carbohydrates are classified as simple and complex carbohydrates. The classification of carbohtdydrates is based on the chemical structure of the food and how fast it absorbs. Simple carbohydrates contains single or double sugars in their chemical structure whereas complex carbohydrates consists of three or more sugars (ahmed 2014). There are four major types of carbohydrates depending on their chemical composition.