Hi everyone ! would like to know about exact difference between negative and positive control in PCR
A positive control is one that you expect to work under the conditions given. The positive control will test your master mix, MgCl2 amounts, primer annealing temperature, and extension times. If your positive control does not work, those results indicate that something is wrong with your annealing or extension times or temperatures, or something is wrong with your MgCl2 or master mix set up. If your positive control does work and your test samples do not, then there could be something else going on such as not enough or too much template. I will often use a plasmid with the desired sequence I want to amplify for my positive control (typically around 500 pg as an amount).
A negative control for PCR is one which should not give you amplicons, typically the negative control will contain no template or will have one or the other primer. Setting up two negative controls, each containing only the forward or reverse primer, should not provide visible amplicons. Therefore, any visible bands might be a result of contamination or multiple opposing binding sites for the designed primers.
Short and sweet of it: A negative control is one you expect not to work under the conditions. A positive control is one you expect to work and to provide you with the expected result.
A positive control is one that you expect to work under the conditions given. The positive control will test your master mix, MgCl2 amounts, primer annealing temperature, and extension times. If your positive control does not work, those results indicate that something is wrong with your annealing or extension times or temperatures, or something is wrong with your MgCl2 or master mix set up. If your positive control does work and your test samples do not, then there could be something else going on such as not enough or too much template. I will often use a plasmid with the desired sequence I want to amplify for my positive control (typically around 500 pg as an amount).
A negative control for PCR is one which should not give you amplicons, typically the negative control will contain no template or will have one or the other primer. Setting up two negative controls, each containing only the forward or reverse primer, should not provide visible amplicons. Therefore, any visible bands might be a result of contamination or multiple opposing binding sites for the designed primers.
Short and sweet of it: A negative control is one you expect not to work under the conditions. A positive control is one you expect to work and to provide you with the expected result.
In positive control the amplicon should come. you load the known sample. In negative control the amplicon should not come. If anything occurs vice versa then there is a problem in the method...
A positive control indicates the right mastermix set up and PCR program (if it worked). And a negative control is the check for contamination of your reagents (if a band appears, there is a contamination during the process).
Positive control is a control reaction using a known amount of template. A positive control is usually used to check that the primer set or primer–probe set works and that the reaction has been set up correctly.
Negative control is a control reaction that contains all essential components of the amplification reaction except the template. This enables detection of contamination due to contaminated reagents or foreign DNA, e.g., from previous PCRs.
Dear, Bharathy Sukumar , I want to thank you for answering my question
Just an addition to what have been said, In PCR, negative controls as Non-template control (NTC) in which you add water (instead of DNA sample) with MasterMix and desired pair of F & R primers. If any amplification takes place, this would mean that either water or mastermix is contaminated. This will help you to solve any issues related to false positive amplification.
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