G418 disulfate (FW 692.7) is an antibiotic used to select transfected mammalian cells in tissue culture. The standard working concentration for selection is 400 µg/mL of active ingredient in culture medium. The bottle states that it contains 71% active ingredient. You need to make a 100x stock in medium and adjust the pH before you apply it to cells. How much powder should be added to make 10 mL of stock solution? How much do you add to a 2 mL culture dish?

A 250mL solution of penicillin and streptomycin needs to be made from penicillin G powder and streptomycin sulfate powder. Can you explain how to make this? Please show details, thank you.

A culture of S. cerevisea has an overnight OD of 2.3 (1.0 OD is approx 1.0x107 cells/ml) You will be plating 100µl onto agar and want the final count of colonies on the plate to be around 300 colonies.  How much of the 2.3 OD culture must you use to get a 500µl subdilution (with sterile water), so that you have diluted enough to get approx 300 colonies per 100ul

If the volume of a Staphylococcus aureus cell is estimated at 0.5 μm3, how many cells could be accommodated, in principle, in 5 mL of saturated culture? (1 mL = 1 cm3). Show your calculations.

Determine the concentration of L. monocytogenes enumerated from the apple slice based on the information below. You must draw your serial dilution and show your mathematical calculation.  The apple slice (12 g) was first mixed with 108 ml of sterile 0.1% peptone water. After, 1 ml was added to tube containing 9 ml of sterile 0.1% peptone water. Process was repeated with two additional tubes. 1 ml was pipetted from tubes 2 and 3 onto MOX media. Plates were incubated at 37 for 48 hours. The pictures below show the plates from tube 2 (left) and tube 3 (right).

Based on prior experiments, you have determined that for a culture of S. aureus an absorbance reading of 1.0 AU650 is approximately equal to 7.25 x 106 cells/mL.How many cells should be present after 10 generations in a 1 mL culture, if the initial cell culture had an absorbance reading of 0.5? (3 Points)

what is the most efficient way to solve this dilution word problem?

I was trying to set this problem where the units cancel out. You are given ampicillin, with a recommended dose of 35 mg/kg , to a child with a mass of 21 kg. If stock on hand is 250 mg/ capsule, how many capsules should be given. How should I set this conversion problem up and it's also asking to express the number of capsules as an integer

When running a gel, the lane loaded with a negative control sample should will always show a band that lines up with the experimental band, regardless if the sample is contaminated. not show a band, which indicates the sample is contaminated. show a band, which indicates that the sample is not contaminated. not show a band, which indicates that the sample is not contaminated.

A culture of S. cerevisea has an overnight OD of 4.5 (1.0 OD is approx 1.0x107 cells/ml) You will be plating 100µl onto agar and want the final count of colonies on the plate to be around 300 colonies.  How much of the 4.5 OD culture must you use to get a 500µl subdilution (with sterile water), so that you have diluted enough to get approx 300 colonies per 100ul