View the PowerPoint slideshow, as well as the videos below to gain insight as to how DNA is transcribed into mRNA. When you are finished, move on to learn about Translation. Important vocabulary terms are highlighted in orange
Now that you understand the make-up of DNA, it's time to learn how the genetic code is tranlated into physical structures. This process is broken up into two parts: transcription and translation. Transcription, which occurs in the nucleus, is simply the process by which DNA is transcribed into the second type of nucleic acid, RNA. There are three types of RNA: ribosomal (rRNA), transfer (tRNA), and messenger (mRNA). At the conclusion of transcription, the cell will have synthesized a mRNA strand from a DNA template. The mRNA strand (and RNA in general for that matter) has some structural differences when compared to DNA. First of all, RNA is single-stranded, whereas DNA is composed of a double strand. In addition, the nitrogneous base Thymine (T) is absent in RNA, and has been replaced by Uracil (U). The template DNA strand is unwound, then "transcribed" by an enzyme called RNA polymerase. The RNA polymerase moves along the DNA until it reaches a terminator sequence. At this point, the mRNA strand is completely assembled and ready for the next step.