Reference no: EM132615189 , Length: word count:1100
Lab report 1:
To understand the effect of different temperatures on bacterial growth.
1. Retrieve 5mL of the sterile broth (before inoculating!) to be used as a blank.
2. Inoculate TSB with E. coli suspension (zero time). The exact volume is to be calculated in class depending on the absorbance of the overnight culture (-5mL).
"Dilution Equation" Ci x Vi = Cf x Vf, where "C" and "V" represent "concentration" and "volume", and "i" and "f" represent "initial" and "final," respectively.
3. "Blank" the spectrophotometers using lmL of sterile TSB. Remember that absorbance is always measured relative to a blank.
4. Remove 3 mL of culture using a sterile pipette and deposit into a cuvette. Label the cuvettes. Repeat for all your samples.
5. Carefully insert the cuvette into the spectrophotometer in the correct orientation (so that the beam goes through the clear side). Make sure the spectrophotometer is set to read OD600 and measure the absorbance.
6. Record the reading and the clock time. Use this as your time zero.
7. Return the broths back to the conditions you are testing ASAP.
8. Rinse the samples off the cuvettes with distilled water into a glass beaker and set the cuvettes upside down in a paper towel until thy next reading.
9. Take absorbance readings every 30 minutes.
10. Repeat throughout the day.
Laboratory Exercise 2
Photosynthesis
Different plant species use different biochemical pathways of carbon acquisition
1- C3 plants such as rice, wheat, and potato: photosynthesis only uses the Calvin Cycle for fixing CO2 catalyzed by ribulose-1,5-bisphosphate carboxylase (Rubisco), which takes place inside of the chloroplast in the mesophyll cell (one compartment). The first product is a 3carbon molecule of phosphoglycerate (it is the first molecule formed as part of the Calvin cycle)
2- C4 plants such as maize, sorghum, and sugarcane: photosynthesis is partitioned between mesophyll and bundle sheath cells (two compartments). The first product is a 4-carbon molecule of oxaloacetate which is metabolized into malate and then diffuses into the bundle
sheath cell where its decarboxylated to provided increased concentration of CO2 around Rubisco 4 Enter the Calvin cycle.
3- CAM plants such as cactus, pineapple, orchids: the initial capture of CO2 is into 4 carbon acid (malic acid) and takes place at night while the incorporation of CO, into Calvin cycle occurs during the day with the aid of Rubisco carboxylase.
Procedure: pH of CAM and C3 plant leaves
Materials needed:
• CAM-plant • Wash bottle (distilled water)
• C3-plant • Beaker to wash pH meter electrode
• Scissors • 20-30 mL beakers or 50 mL falcon tubes
• Mortar and pestle • 0.01M NaOH
• dH2O • Burette for titration
• Sand • Stirring rod
• 10 mL Pipette and pipette aid • Magnetic stirrer (small size)
Method:
Need to have three replicates (samples) of each plant
1. Using scissors, gently remove a piece of leaf from both provided CAM and C3 plant
2. Wash leaf then blot dry with paper towel
3. Weight the leaf pieces and note it down (get about 1g of leaf)
4. Grind in mortar and pestle with pinch of clean sand and 5 mL water
5. When you get homogenous mixture, pour into small beaker (or 50 mL falcon tube)
6. Add 10 mL of water and mix thoroughly with stirring rod
7. Place pH meter probe in solution and determine pH and write it down
8. Repeat the same with the other samples
9. ONLY FOR CAM Plants: Titrate the solution to pH 7 using 0.01M NaOH.
10. Add stir magnetic bar to the beaker (you may add extra few mLs water if needed) or keep using the falcon tube with continuous stirring.
11. Be careful not to overshoot - slow down once you have reached a pH of 6-6.5
12. Record the amount of base added and convert to μmol malic acid (1ml of base = 10μmol of base = 10μmol of malic acid)
Attachment:- Lab reports.rar