My senior thesis is firmly rooted in my final project for my genetics class. The scope of the project is going to spread out widely from it, and its strong base will help for a reasonable amount of breadth. Including analytical and biochemical methods with this experiment will give it substance. Perhaps some additional inorganic chemistry as I take the course next spring will further reinforce my experiment. My current goal is to reinforce my findings from last spring's genetics experiment, then spread out from that experiment in a systematic manner.
The conclusions reached from the previous spring include the following:
1) Neurospora crassa uses invertase to break down sucrose into glucose and fructose, demonstrated by a positive Benedict's test on the media of the experimental cultures.
2) Glucose is digested by Neurospora as demonstrated by the change in optical rotation from positive to negative.
3) The albino and wild-type strains of Neurospora use their carbohydrate source differently. The initial optical rotation of all samples was approximately +0.95 degrees. The final average optical rotation of the three wild-type cultures was -0.15 degrees, while the average for the albino strains was -0.28 degrees.
4) The relationship between the final dry weight of the Neurospora and the final optical rotation is linear for both the wild-type and albino strains, with R squared values of 0.997 and 0.988 respectively.
The data lend themselves to the theory that the carbohydrate utilization of Neurospora has the following steps: First, hydrolize the sucrose; second, digest glucose; third, digest fructose. The optical rotation becomse increasingly negative for all six experimental flasks. All three of the wild-type Neurospora have larger negative optical rotations after 24 hours than after 48 hours. The optical rotation becomes increasingly negative, then slowly reapproaches zero. This hints at the idea that glucose is a preferential nutrient source, then fructose becomes digested out of necessity. However, this hypothesis needs more experimentation to support it.
The scope of my senior experiment will cover all of the following topics:
1) Precise curves of change in optical rotation over time for the three experimental strains: wild-type, albino, and slow-grower.
2) Better assessment of the linear relationship between final optical rotation and dry weight
3) Demonstration of the glucose and fructose utilization of Neurospora crassa through change in optical rotation over time
The final goal, overall, is to study the carbohydrate usage of Neurospora in depth and show how it relates to the growth of the organism. The analytical method of polarimetry lends itself exceptionally well to studying this process.
Posted by StephanieReigh at November 1, 2004 05:10 PM