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basic question regarding PCR - (Jun/12/2007 )

this may seem like a stupid question to many, but I know during PCR, the polymerase rolls along and adds dNTPs to the growing chain, but to be a complete DNA strand, there also need to be sugar and phosphate backbones. But those things are not included in the standard PCR mixtures, so where do they come from or what adds those backbones to the new strands? Thanks a lot.


dNTP= 2´-Desoxyribonucleosid-5´-triphosphate

..."A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups."...


thanks a lot, I am new to molecular biology. Another question, when staining the gel with EtBr, how concerned should I be of the carcinogenic effects? Is anything that came to contact with EB pretty much off limits unless wearing 2 sets of gloves? How long will EB be active on things like bench top, shelves, beakers? Is it forever contaminated with EB or does EB degrade over time? Thanks.


This seems to be a hot topic among biologists as some people don't seem to worry at all when working with ErBr and others take extreme measures to avoid contact. Personally, I don't handle anything without gloves. I figure better safe than sorry. I know that EtBr breaks down with light and can be washed off plastic fairly easily so things can be de-contaminated.


What about things like glass, benchtop, wooden shelves, are there any ways to decontaminate those type things, like special soap, detergent or sprays?


washing with detergent and water is probably the best option. No need for special sprays. Although you can use acetone if you want. Acetone gets rid of almost anything under the sun.

EtBr spill used to be handles by bleach, but that actually produced a more carcinogenic intermediate, before final degredation. So water and soap it is, at least in my department.

And really, low concentrations of EtBr is actually required to stain a gel. So one way to limit EtBr exposure is to use it at the right concentration.


is EB airborne? can I breathe it in, by being near the EB workstation?


it can be come a dust if a solution is left out to dry. So don't leave EtBr solution out to dry.