Genetic Diversity Via Zea Maize

Investigation 5

Understanding how traits are passed down from parent to offspring is done firstly by understanding the law of segregation. This law states that an individual will carry two traits but only pass down one allele to their offspring. This law allows scientists form predictions of the phenotype and genotype of the offspring using a Punnett square (as long as the model of inheritance is known). While this information certainly adds a significant amount of predictability to genetics, one thing that must be taken into consideration is the environment. Whether or not the conclusion of this question is intuitive, the results must be tested to be absolutely sure. Thus making our guiding question: Can the environment influence the genotype or the phenotype of an organism such as Zea maize? 

        The first step of this lab was to plant a number of different maize seeds into containers that differed in the amount of light they received. This was done to test the levels of chlorophyll at the end to see if the amount of light actually changed the genetics of the plant. Once they were planted, and were given two weeks to grow. After the allotted time expired, a plant was chosen by each tester. The plants height was measured from the soil to the top of the plant. Once this data was obtained, a portion of the leaf was snipped off and weighed for later calculations. The genotype (light or no light), and the phenotype (white/pale/green) was also recorded for later testing. Each of the vital statistics were taken a second time to ensure the data’s utmost accuracy. Once measurements had been recorded, the group could begin obtaining the Relative Chlorophyll Concentration (RCC), which is expressed by the equation: RCC = OD • Volume / Weight, where OD is the absorbance of the leaf. To obtain the absorbance, the leaf was placed into a mortar and pestle along with 12 mL of acetone, and was grinded up and placed into a centrifuge tube. The tube was the spun for five minutes at 5000 rpm in order to fully mix the various remains of the leaf. Once the centrifuge was complete, the tubes were removed and placed into a Spec20 where the absorbance was measured at 450 nm wave lengths (which is the chlorophyll peak), so the amount of chlorophyll could be determined. Thus making the complete equation: RCC = 0.745 • (15 mL / 0.205 g), which gave us an RCC value of 54. 51 in one instance. The remaining RCC values were plotted in a graph such that y represented the height and x represented the RCC value. [pic 1]

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