Zero Order

My favorite things

Posted in Uncategorized by Amy Ross on July 16, 2010

Well, it’s Friday, and the extreme heat we’ve been having has made me lazy. In lieu of more serious content, I’d like to take a moment and recognize three things that make my workday a little easier:

1.  The Molarity Calculator page. My postdoc showed this to me one day, and it’s a lifesaver. You don’t expect me to do all those calculations by hand, do you?

2. MTS assay. I’ve talked a little about MTS before. It’s a measure of how many live cells are present in a given sample.  The MTS dye is reduced to formazan in the presence of mitochondrial reductase, changing the color of the solution. The color change can be measured by spectrophotometry. It’s an easy test to perform and there’s no solution to mix.

3. Last but not least, the automated cell counter. Cells can be counted by hand using a device called a hemocytometer (named because it was initially used to count blood cells). The hemocytometer consists of two blocks divided into nine squares each. A  couple of drops of cell-media suspension are placed on the hemocytometer, and s cover slip is placed on top. Using a microscope, cells in the squares are counted, averaged per square, and multiplied by 1000 to get the cell count per milliliter.  I’ve done this once. It wasn’t too bad, but I only had 12-20 cells per square. If you get into the hundreds, it’s much worse.

The cell counter is faster,  more accurate, and fairly easy to use. The one in our lab measures particle size by measuring change in electrical impedance. The only downside is it can’t process large cell counts.

An honorable mention goes to Wikipedia chemistry articles. How did anyone get through Orgo without them? I guess they had to look up all those densities and boiling points in a book! 🙂


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