AP biology fermentation lab, Assignments of Biology

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Name: Fermentation Lab Introduction : For most cells, cellular respiration can be divided into two general steps; glycolysis and oxidative phosphorylation. Glycolysis is the set of chemical reactions that starts the breakdown of glucose. These reactions take place in the cytosol and do not require oxygen (O2) and are therefore anaerobic. If oxygen is available, cells are able to use the pyruvate from glycolysis in the oxidative phosphorylation phase of aerobic respiration. If oxygen is not available, cells are only able to carry out fermentation, which yields far less ATP than does aerobic respiration. In this experiment, we will test the ability of yeast to ferment different sugars. Two of the sugars (glucose and fructose) are monosaccharides, or simple sugars. The other two sugars (lactose and sucrose) are disaccharides--they are each made up of two simple sugars. Sucrose is composed of linked glucose and fructose monosaccharides and lactose is composed of one glucose monosaccharide and one galactose monosaccharide. Only monosaccharides can be used directly by yeast in fermentation. This means that sucrose and lactose must be broken down to their component monosaccharides by the yeast before fermentation can occur. Because CO2 is released during fermentation of sugars by yeast, it provides a convenient way of measuring how much fermentation (glycolysis) has taken place. Materials: . pig Hypothesis: + Yeast ke Identify the null hypothesis: + Glucose . a oestc Yeast will have the same cate of Ceachon + Fructose pipettes with monosacharides T disathorides + Lactose + 4washer Identify the alternative hypothesis: + Sucrose + Test Tube Yeast will have anigher cate af ceacton + Grease pen Rack With monosacharides then with disachacides . Procedures: + Mix 3 gram (or about half a teaspoon) of yeast with 100 milliliters of warm water in a 250 ml flask. Stir well and wait about 5 mins. Divide your yeast mixture evenly between four 100 ml labelled beakers. (labels should have type of sugar indicated on it). Add 8 grams (or two about 2 teaspoons) of your select carbohydrate. Stir well and let mixture rest for about 10 mins or you see bubbles start to form. Fill a plastic pipet with your yeast and sugar mixture. You want the bulb of the pipet to be full and the tube to be empty and clear of yeast mixture so gas can easily pass through. Invert your pipet so the bulb is at the bottom and tap it a few times to get as much of the mixture out of the tube. You may need to squeeze the bulb a little to get the excess mixture out. Yeast Cut the tip of your pipet tube so that it is shorter than your test tubes or about 3 Mixture inches long. Place a metal washer around your pipet tube. Repeat for all mixtures. Drop the entire apparatus into your labelled test tube. The washer should ensure that your pipet sinks to the bottom. The tip of the pipet tube should be submerged below the surface of the water. Measure the rate of fermentation by counting the bubbles released each minute time for 10 minutes. Record your data on the table.