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Unformatted text preview: 100 50 20 10 1ml added Original Culture (Conc. X) Into 9ml of Water 1ml Transferred (Conc. X) (Conc. X/10) SERIAL DILUTION OK, I’ll admit it. This is not the most adventurous lab you will encounter here, but in terms of the importance of what you will learn it is massive. Truly, it is the most fundamental procedure done in research today, and yet, people often do it wrong. Well, we’re going to make sure you do it right. Dilution is a simple concept; anyone who cleans floors knows that. Basically you take a solution (like PineSol for example,) which is concentrated, and you pour it into a larger volume of water or some other liquid, thus reducing the concentration and making it suitable for mopping. Whenever you are reducing the concentration of something you are diluting it. That’s simple right? The problem is that sometimes you need to know how much you are diluting something. Now the easiest way of doing this would be to make a series of dilutions in which you add a decreasing amount of a compound into aliquots of a solution: Which is fine as long as you can add accurately measure smaller and smaller amounts. Unfortunately sooner or later you reach a limit. A culture can be so highly concentrated that you need to dilute over a million fold to plate the cells. In fact viral cultures often achieve titers in the range of 10 14 virus particles per ml. Since they don’t make a pipette calibrated in the picoliter range (10-12 ) plating bacteria and other microorganisms require a different dilution strategy, known as a dilution series....
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- Spring '08
- Genetics, Test Tube, The Tubes, dilution series