positive/negative controls

[Karnage]

hey guys, im still a bit confused over the purpose of positive and negative controls. Can sum1 explain me the uses and give good examples so that I may understand. It would be greatly appreciated thnx!

[ecoli]

you need a control in order to make sure the results of you experiments are due to the variables you are testing. That being said...

 

a positive control is when you test your experiment against something where you know what the effects will be. a negative control would be when you test the experiment with something you know will have no effect.

 

For example, I was doing a genetics project where I was carrying out PCR, a process that amplifies desired genes. Primers are the molecules that can choose the section of DNA you want to amplify. I designed primers for my desired gene, but I still had to test them, to make sure they worked. In this experiment, I replaced the DNA with water to use a negative control. And I used a set of standard primers that I knew amplified other genes for my positve control.

 

You get it know?

[Connor]

wow, I was gonna use the exact same example. Weird

[Karnage]

K i got it...i used positive and negative controls for my PCR too, along with my reverse transcription before that. I just wanted to know what they were and how they functioned so that I could get a better understanding. Thanks!

[Karnage]

And by the way, of course the standard primers will most like be beta-actin, which most scientists use for their positive controls for PCR. I dunno if you use beta actin in yours.

[ecoli]

I used 16s primers, actually.