QWhat is a promoter and what does it do?

What is a promoter and what does it do?

AExpert Answer

 A promoter is the main regulatory portion of a gene.  The simplest analogy is that a promoter is a “switch” that turns a gene “on” or “off.” It is the portion of the gene where cellular machinery binds before transcribing the DNA blueprint into a useful RNA.  There are different types of RNA that may be transcribed, including messenger RNA’s (mRNAs) that encode useful proteins and regulatory RNAs that mediate gene silencing.  But, the first step is always binding of an RNA polymerase to the gene’s promoter.  No promoter, no useful RNAs or proteins!


In making transgenic plants, the gene of interest inserted into a plant genome must include a promoter to allow this gene to be switched “on” or transcribed.  One of the most common promoters used in engineering GM crops is the CaMV (Cauliflower Mosaic Virus) or “35S”promoter, which is a type of constitutive promoter (always “on”).  Different types of promoters, including those that require specific environmental signals in order to switch “on”, are found throughout the natural world. 


Recent Forbes article by David Kroll on the safety of the CaMV 35S promoter:


Posted on April 11, 2018
Interesting question - that's a good example of how the term "GMO" (genetically modified organism) is too vague to be really useful. In a sense, yes, your genes are modified compared to both of your parents. And you're definitely not genetically identical to your parents (unless you're a yeast, or a starfish, or a willow tree, or some other organism that can reproduce asexually).   But in common usage, the term GMO refers to an organism containing a gene... Read More
Posted on March 1, 2018
I don't see organic foods becoming obsolete in the future, but I could see what qualifies as certified organic changing over time. There is some debate right now about whether or not the meaning of organic is being diluted. For example, look at growing produce hydroponically. There are some who do not want hydroponics to fall under the organic label. They believe organic should be about taking care of the soil as much if not more than growing the crop, and when there's no soil involved... Read More
Posted on March 1, 2018
GMOs are crops - and like any other version of the same crop, where you grow them and how you grow them is far more important than whether they are GMOs. No known system of agriculture can promise that it is sustainable forever; much agricultural research is being devoted to improving the sustainability of agriculture. In this regard, it appears likely that using GM technologies may improve sustainability of a particular crop cultured in a specific manner and place. Other... Read More