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Mr_Saturn512's avatar

Why don't all these factors affect experiments?

Asked by Mr_Saturn512 (346 points ) September 25th, 2012

Bacteria and countless microorganisms are all around us, no matter where we are (unless you’re in a super strict containment facility, but otherwise) right? I mean, sure we have aseptic techniques and wash things down, but there’s still things in the air and things that seep in the room, etc.

Then how come scientists are able to do experiments without having results skewered by this fact? I mean, I’ve been in many lab courses and I had to do things with DNA, for example. But I always wondered, since nothing is truly sterile, why nothing happens to the DNA. I also had a neuro class where we had to dissect rat brains to get neurons. How come we’re still able to visualize the neurons in the end being that there’s all this microbiota all around us?

I feel stupid asking this but. . . whatever.

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3 Answers

tedd's avatar

The effect of micro-organism DNA in a regular DNA sample would be minute, if not non-existent. The millions of DNA that are fed through the system are what give you your results, in essence you get an average of all the results, which would eliminate the “noise” of a handful of contaminant DNA that find their way into your results.

As far as the neurons I have no direct experience, but I would imagine it’s something similar. If you take a sample, which may appear small to the naked eye, it will probably have millions or billions of neurons on it. Though it may be contaminated by some micro-organisms or what have you (and I’m sure it is), when you put it under a microscope that allows you to see the individual neurons, they’re probably far out-numbering the contaminants.

gasman's avatar

When they test rock samples from outer space (meteorites, moon rocks, etc.) for the presence of bacteria & other microbial life, they worry A LOT about terrestrial contamination. All of the tentative “discoveries” of extraterrestrial life on rocks turned out to be earthly organisms. It’s a “signal versus noise” issue.

As for neurons, they are much larger than bacteria, up to 100 microns for the soma (cell body). Bacteria, by contrast, are about 1 micron in diameter, at the optical limit of light microscopes. Viruses are smaller still & can only be seen with electron microscopes.

Gabby101's avatar

I used to work in a microbiology lab and we worked in what was called a ‘hood.” It’s an area that is sterile and keeps out contaminants by using air flow. Here is something from wikipedia

People using the hood had to wear gloves and a mask and there was a whole routine on how you got instruments into the hood and how to clean it after use. If you even thought you had contaminated the hood you had to clean it and if a project were possibly contaminated it had to be thrown out. It was a huge deal keeping that thing sterile.

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