Sense strand

In genetics, a sense strand is the strand of DNA transcribed into mRNA during transcription. The immediate product of this transcription is called an (initial) RNA transcript, which is the same as the sense strand except the nucleotides are RNA instead of DNA. This initial RNA transcript undergoes intron deletion prior to translation. The intron deletion process is called splicing. Each splicing event removes a piece of RNA and rejoins the adjacent ends immediately. The end product is called mRNA and is co-linear with the sense strand of DNA. That is, even though an mRNA has parts missing compared to the sense strand DNA, no part of an mRNA has flipped its head-tail orientation. Strictly speaking, only the mRNA makes "sense" with the genetic code as the translated protein peptide sequence can be directly inferred from this strand. The sense strand DNA however, has a lot of 'garbage' stuffed in between genetic codes. (This is true in most eukaryotic genes. Prokaryotes usually don't have 'garbage' in their sense strand DNA.) The "anti-sense" strand is complementary to the "sense" and is the actual template for mRNA synthesis.

Different genes are found on different "sides" of the DNA. Not all genes correspond to only one strand of DNA.

Knowing the difference between the sense and anti-sense strands is important in certain molecular biology applications. For example, in microarray expression technologies, it is important to know which strand is "viewed" on the array. An array can correspond to either strand; however, a single array will be made entirely of "sense" or "anti-sense" strands.

Identifying the different strands is also important in understanding small interfering RNAs, or siRNA.