Homework_1 - AEP 470, Fall 2008 Due date: Monday...

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AEP 470, Fall 2008 Homework problem set # 1 Due date: Monday Sep-29-2008 1. (15 points) Imagine a calcium measurement in a microscope from a cell loaded with the indicator dye such as fura-2. Excitation is done at two alternating wavelengths, 358±5 nm (isosbestic point) and 390±6 nm. Fluorescence emission is measured in a 490-520 nm band. The apparatus is calibrated performing measurements with three different calcium concentrations giving the average fluorescence intensities in the table (in A/D converter units): The measured signals include some background. To determine the background, measurements were also performed in several cells that were not loaded with the indicator dye. The average background values were 430 at 358 nm and 328 at 390 nm. What is the apparent dissociation constant of the indicator dye in this experiment? In a subsequent experiment the following fluorescence values are measured: What are the calcium concentrations at the different time points? [Ca 2+ ] F 358 F 390 0 (10 mM EGTA) 2320 1678 170 nM (5 mM CaCl 2 , 10 mM EGTA) 2430 1230 2 mM 2478 422 F 358 F 390 Before stimulation 2410 1428 2 s after stimulation 2385 564 30s after stimulation 2321 748 60s after stimulation 2275 923 180s after stimulation 2225 926
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AEP 470, Fall 2008 Homework problem set # 1 2. (10 points) The molecule beta-carotene has 11 conjugated double bonds and an
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Homework_1 - AEP 470, Fall 2008 Due date: Monday...

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