Specificity of enzymes: Sugars metabolized by yeast.


Aim: The aim of this experiment is to determine whether yeast is sugar specific. Are there some sugars that it breaks down better than others, are there sugars it cannot breakdown and do these results have anything to do with the sugars’ structural formulae?


Hypothesis: It may be predicted that yeast will probably break down some sugars better than others. Glucose is probably the sugar that will be more successful in being broken down as it is the sugar used in most yeast experiments or commercial uses. Maltose might produce satisfying results as glucose is a product of maltase and maltose. However the outcome of this supposition is yet to be determined.


Variables:




What aspects were maintained the same


What aspects were modified purposely


What aspects couldn’t be controlled



o The size of the test tubes used
o The size of the fermentation tubes within the groups
o The amount of yeast suspension in each tube (1 cm³)
o The amount of sugar transferred into each fermentation tube (1 cm³)
o The amount of time (interval) each fermentation tube was measured after
o The temperature of the water bath (37ºC)

o The type of sugar used in each fermentation tube; distilled water, glucose, fructose, galactose, sorbose and maltose.

o each group used different sized fermentation tubes
o one group began by measuring the amount of air in the fermentation whilst the other two measured the height of the liquid
o the exact amount of distilled water added to each fermentation tube to the brim
o one group measured 15 seconds intervals whilst the other two measured 10 second intervals
Apparatus:


· distilled water


· glucose


· fructose


· galactose


· sorbose


· maltose


· 7 syringes


· 6 fermentation tubes


· 6 test tubes


· 37ºC waterbath


· yeast suspension


· pencil


Diagram:



Results and Observations:


Time (secs)


0


10


20


30


40


50


60


Test Tube


G1


G2


G3


G1


G2


G3


G1


G2


G3


G1


G2


G3


G1


G2


G3


G1


G2


G3


G1


G2


G3


Distilled


9,3


9,5


9,9


9,0


9,5


9,8


9,5


9,0


9,5


9,8


9,1


9,5


9,8


9,0


9,5


9,8


9,5


Glucose


9,2


9,6


9,9


7,2


9,5


9,7


8,0


8,8


5,9


5,7


4,4


3,8


4,2


1,5


0,0


Fructose


9,25


9,6


10,0


7,5


9,5


9,9


8,3


9,5


9,3


5,5


7,1


4,8


3,9


7,6


4,3


0,5


0,0


Galactose


8,9


9,5


9,9


8,7


9,4


9,8


9,3


8,6


9,3


9,8


8,5


9,3


9,8


8,5


9,3


9,2


9,3


Sorbose


9,15


9,7


9,8


8,85


9,5


9,6


9,5


8,9


9,5


9,6


8,3


9,4


9,6


8,8


9,4


9,6


9,4


Maltose


9,7


9,7


7,1


7,1


6,2


4,8


3,6











Only group 2 was able to provide results for maltose.



Comparative Results of all sugars for group 1


Time (secs)


0


10


20


30


40


50


60


Distilled


9,3


9,0


9,0


9,1


9,0


Glucose


9,2


7,2


9


Fructose


9,25


7,5


9,5


7,1


7,6


Galactose


8,9


8,7


8,6


8,5


8,5


Sorbose


9,15


8,85


8,9


8,3


8,8



Comparative Results of all sugars for group 2


Time (secs)


0


10


20


30


40


50


60


Distilled


9,5


9,5


9,5


9,5


9,5


9,5


9,5


Glucose


10


10


8


6


4


4


0


Fructose


9,6


9,5


8,3


9,3


4,8


4,3


0,0


Galactose


9,5


9,4


9,3


9,3


9,3


9,3


9,3


Sorbose


9,7


9,5


9,5


9,5


9,4


9,4


9,4


Maltose


9,7


9,7


7,1


7,1


6,2


4,8


3,6



Comparative Results of all sugars for group 3


Time (secs)


0


10


20


30


40


50


60


Distilled


9,9


9,8


9,8


9,8


9,8


Glucose


9,9


9,7


6


4


2


Fructose


10,0


9,9


5,5


3,9


0,5


Galactose


9,9


9,8


9,8


9,8


9,2


Sorbose


9,8


9,6


9,6


9,6


9,6



Conclusion:




Evaluation: