Lab 4 - Activity of Nitrate Reductase in Bean Seedlings According to Time Light and Induced Nitrate Parameters Introduction Nitrate reductase(NR is an

Lab 4 - Activity of Nitrate Reductase in Bean Seedlings...

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Activity of Nitrate Reductase in Bean Seedlings According to Time, Light, and Induced Nitrate Parameters Introduction Nitrate reductase (NR) is an enzyme found in plant leaves that catalyzes the reduction of nitrate to nitrite, the first reaction in a series that produces nitrite and ammonia to be used for plant growth. Nitrate levels are the most important determining factor in cellular development and growth; it is therefore important to understand the correlation between nitrate assimilation and other influencing factors (Crawford, 1995). We will conduct three experiments in order to observe the relationship between nitrate reductase activity and three conditions: induction time, light (in tandem with mineral and nitrate solution), and induced nitrate. We hypothesized the following outcomes for each manipulation: NR activity will increase with induction time, seedlings grown in light and with nitrate solution will exhibit greater NR activity in comparison to those grown in the dark without nitrate and that lack of nitrate and lack of light produce interchangeable results, and that growth under high nitrate concentrations will result in high NR activity in comparison to those grown with less concentrated nitrate. This is because with increased nitrate concentration in added solutions, NR has more molecules to catalyze. Light may stimulate NR activities as well due to photosynthetic factors. Methods First, 7 standard nitrate stocks solutions, each containing 2.5mL SA and 2.5mL NEED were put in a spectrophotometer and absorptions at 540nm were recorded. These data were used to construct a standard curve according to nmole nitrite. Each experiment entailed a different
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  • Fall '09
  • SACK
  • Nitrate, nr activity, Crawford N

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