Today’s word of the week is transcription, in the biological sense. Not the process of converting speech into a written document (though I know a lot of science writers who spend a lot of time doing that, so I suppose it could count as part of the biological definition), but the part of the central dogma that is incredibly important to molecular biology. The process of information flow is this:
DNA -> RNA -> protein
This represents the flow of information in a cell at its most basic level. DNA is transcribed to RNA, RNA is translated to protein. We used to think that this flow only went in one direction. We now know (thanks to retroviruses like HIV) that RNA can transcribe back to DNA. We also know that proteins can influence DNA transcription, though whether proteins can translate back to RNA is not known (it seems like a big leap to me, but a lot of this stuff seemed like big leaps to a lot of people, only a few years ago).
And in all this, there is transcription.
Transcription describes the process of DNA -> RNA, the process performed by RNA polymerase and other enzymes, which break up the bonds between two DNA strands, make a new RNA pair to one of them (RNA nucleotides are just like DNA nucleotides, with the exception of Uracil for Thymine and ribose for deoxyribose), and allow the DNA to be attached to its original pair strand, ready to be transcribed again or put away for another time. Transcription is the first step of what will become gene expression, and things that affect it affect what proteins are made, and in the end, the function of the cell as a whole.