Bio5LAManual12f

Then replace the co2 laden air with fresh air from

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Unformatted text preview: ples/s or the “interval” to 10s/sample. Change the “length” to 300s. Tap “OK”. To start the run tap the “green arrow” in the lower right. The graph will appear. Let the run continue undisturbed for 5 minutes. 4. After the 5 minute run, tap “analyze”, then “curve fit” and then check the box next to “CO2”. Tap the down arrow next to the “choose fit” box and select “linear”. Find the slope m which is ppm CO2/s and record this value in your notebook. 5. Repeat the measurement a second and third time if time permits. However, if the CO2 reading is getting close to 10,000 ppm after any trial perform the following steps: Remove the sensor, lid and yeast sample from the chamber. Then replace the CO2- laden air with fresh air from the room by waving the chamber around. Replace the yeast culture and reinsert the sensor. 6. When finished with each sample transfer the contents of the petri dish back into the original tubes and place them in the hot (60°C) water bath for 15 minutes. Remove the tubes and allow them to cool before repeating steps 2-4 for all three samples. 7. See page 4 for a guide describing the calculations needed to process this data. CELLULAR RESPIRATION Cellular respiration is the main metabolic pathway for ATP production that is used by animals, plants (especially at night), and many microorganisms. The conversion of sugars to CO2 and water liberates much more of the energy stored in the sugar than does fermentation (about 16 times as much ATP is generated in comparison to fermentation of the same amount of sugar). Measurement of the rate of CO2 production by an aerobic organism provides a useful measure of its rate of energy production. As for the yeast you will use a Vernier CO2 gas sensor inserted into a closed system containing corn seedlings undergoing cellular respiration. Cellular Respiration by Corn Seedlings Experimental Protocol: A. Preparation of corn seedlings: 1. Obtain and weigh a 250 ml Nalgene bottle and record its weight in your notebook. Tilt the bottle on its side and add about 25 corn seedlings (your TA will tell you how many) with radicles (the big white things that stick out of the corn kernel), ranging from 1.0 to 3.0 cm in length. Be careful not to handle them roughly or lump them at the bottom of the bottle – they should be spread out in a single layer along the side of the bottle. This arrangement will allow all of the seeds to have adequate gas exchange with the air in the bottle. 2. Once the seeds are in the bottle, weigh the bottle with the seeds. The weight of the seeds can then be calculated and recorded on the worksheet. B. Measurement of CO2 production: 1. Insert the CO2 sensor into the neck of the Nalgene bottle. Biology 05LA – Fall Qtr. 2012 Lab 6 – page 4 2. On the touchscreen of the LabQuest recorder, tap the icon in the upper left corner that looks like a speedometer with the stylus. Next tap “sensors” and then “data collection”. Change the “rate” to 0.1 samples/s or the “interval” to 10s/sample. Change the “length” to 300s. Tap “OK”. To start the run tap the “green arrow” in the lower right. The graph will appear. Let the run continue undisturbed for 5 minutes. 3. After the 5 minute run, tap “analyze”, then “curve fit” and then check the box next to “CO2”. Tap the down arrow next to the “choose fit” box and select “linear”. Find the slope m which is ppm CO2/s and record in your notebook. 4. Repeat the measurement a second and third time if time permits. However, if the CO2 reading is getting close to 10,000 ppm after any trial perform the following steps: Remove the sensor, lid and yeast sample from the chamber. Then replace the CO2- laden air with fresh air from the room by waving the chamber around. Replace the yeast culture and reinsert the sensor. 5. When finished with the three readings transfer the contents of the bottle into a test tube and place it in the hot (60°C) water bath for 15 minutes. Remove the tube and allow them to cool before transferring the seedlings back into the bottle and repeating steps 1-3. (This step may be eliminated at the discretion of the TA due to time constraints). ***** 1. Convert the slope from ppm/s to ml/hour: a. First convert ppm to ml using a proportion: average slope = ml of gas produced 106 volume of container* b. Second, convert seconds to hours: ml gas produced (from step 1a) sec x 3600 sec 1 hr = ml gas produced (use this value for part 2) hr *The large chamber has a volume of 2,000 ml and the bottle has a volume of 310 ml 2. Determine how many moles of gas were produced: (1 mole of gas occupies 22.4 liters or 22,400 milliliters.) ml gas produced (from part 1) x 1 mole gas = hr 22,400 ml 3. Calculate rate of ATP production in moles. FERMENTATION Remember that for every one mole of CO2 produced, there is one mole of ATP produced. So: moles CO2 prod.* x 1 mole ATP = moles ATP prod.** hr 1 mole CO2 hr *(from step 3) ** (use this value for part 4) moles gas produced (use this value for...
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This note was uploaded on 08/27/2013 for the course BIO BIOL05LA taught by Professor Abbottl during the Fall '12 term at UC Riverside.

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