Preparation of standard curve Use a 1 ml pipette for volumes

Preparation of standard curve Use a 1 ml pipette for volumes of 0.5 ml and use a 5 ml pipette for larger volumes. Pipettes can be reused, but each one must only be used for one of the two liquids. Tube number 8 is the blank. Follow the instructions provided for the spectrophotometer on your lab bench and use tube number 8 to zero the instrument. Be sure to set the wavelength to 540 nm. Read the OD tubes 1 through 7 and record the values in the last column of the

Solution

Answer:

The OD540 have been measured for various dilutions of the culture for preparing a standard curve.

Since nothing has been provided as the number of cell/mL to be considered against OD540 = 1, we shall take the standard value: 1OD = 2.5 * 10⁸ cells/mL (for E. coli cells)

1. OD540 = 0.95 (undiluted)

So, number of cells/mL = 0.95 * 2.5 * 10⁸ cells/mL = 2.375 * 10⁸ cells/mL

2. OD540 = 0.89

So, number of cells/mL = 0.89 * 2.5 * 10⁸ cells/mL = 2.225 * 10⁸ cells/mL

3. OD540 = 0.75

So, number of cells/mL = 0.75 * 2.5 * 10⁸ cells/mL = 1.875 * 10⁸ cells/mL

4. OD540 = 0.45

So, number of cells/mL = 0.45 * 2.5 * 10⁸ cells/mL = 1.125 * 10⁸ cells/mL

5. OD540 = 0.11

So, number of cells/mL = 0.11 * 2.5 * 10⁸ cells/mL = 0.275 * 10⁸ cells/mL

6. OD540 = 0.0

So, number of cells/mL = 0.0 * 2.5 * 10⁸ cells/mL = 0 cells/mL

7. OD540 = 0.0

So, number of cells/mL = 0.0 * 2.5 * 10⁸ cells/mL = 0 cells/mL

8. OD540 = 0.0

So, number of cells/mL = 0.0 * 2.5 * 10⁸ cells/mL = 0 cells/mL

The above values so obtained can be used to plot the standard curve with Number of cells versus OD540.