THE ADVANTAGES AND DISADVANTAGES OF THE VARIOUS MICROBIAL CULTURE TECHNIQUES. It is time consuming especially when diluting the original sample by serial dilution. Advantages: Quick and Easy Disadvantages. A serial dilution is the stepwise dilution of a substance in solution. Usually the dilution factor at each step is constant.

Part C: UV Experiments Serial Dilutions and Viable Cell Counts The experiment Observing the Effects of Solar Ultraviolet Radiation on Cells shows that when cells are exposed to sunlight all, some, or none of them may be killed. Many experimental questions can be answered with qualitative answers like 'all, some, or none.' Other questions may require quantitative answers.

For example, in the next experiment you will use the sensitive yeast strain to measure the intensity of solar UV radiation by measuring the fraction of cells exposed that survive. To get quantitative answers about yeast survival you must put a known numbers of viable (living) cells onto the agar plates and then count the number that remain after being exposed. You can determine the number of viable cells by counting the colonies that grow up on the agar growth medium in a Petri plate by assuming that each colony grows from a single viable cell.

Catt Acoustic Keygen Generator. This is usually a reasonable assumption. Experiment: In the experiment that follows you will learn how to measure the number of viable cells on a Petri plate. You will be able to use this procedure whenever you need to measure the number of cells that survive an exposure to radiation or some other treatment. First you will estimate the number of cells in a liquid suspension in order to plate a reasonable number of cells.

For this you will use one of the most sophisticated and sensitive optical instruments in existence, the human eye. With surprisingly little practice you can learn to estimate the number of cells in a suspension by just looking at it. You can estimate cell density because of your eyes' fairly sharp threshold for observing turbidity (cloudiness).

When viewed in a standard 13 100 mm glass tube, yeast suspensions of less than about 1 million cells per mL are not visibly turbid. Above this threshold density, the suspension is cloudy.

When you adjust the number of cells in a suspension until just barely visible, you obtain a suspension of known density (approximately 1 106 cells/ml). When you have a suspension that contains approximately 1 106 cells/ml, you will dilute it to get the right concentration for plating.

You will make the dilutions in known steps so you can calculate the number of cells in each dilution tube. This procedure helps you plate a countable number of colonies.

Serial dilution is usually 1/10 dilution. Therefore after a series of dilutions, you have a logarithmic curve of concentration (log10). Basically, if diluting 1/10 and startin g off with 1 molar solution, first dilution = 0.1M, 2nd = 0.01M, 3rd = 0.001M. If making a 0.001M solution involved weighing out 0.005g of a salt for example, the error in making this solution out would be very large in comparison to weighing out 5g (1M) and diluting it 3 times by serial dilution. The benefit of it is mainly accuracy.

It is very simple. You just boil the water. You boil the milk. It kills the germs.