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General Genetics/Transcription

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Transcription is the process by which the genetic information in DNA is converted into RNA. The mechanism of transcription can be described simply in 6 steps (5 in prokaryotes):

  1. The section of DNA to be transcribed is recognized by proteins involved in transcription.
  2. Hydrogen bonds between base pairs of DNA are broken and the DNA double helix "unzips."
  3. Complimentary RNA bases bind to the now exposed DNA bases
  4. RNA Polymerase binds the RNA bases together to form a strand of mRNA
  5. Hydrogen bonds formed between the original DNA strand and the new RNA strand are broken
  6. in eukaryotes, the new RNA strand is further processed and moves to the cytoplasm.

The segment of DNA to be transcribed is called a transcription unit, and contains at least one gene. If this gene codes for a protein, the RNA transcription product is called Messenger RNA, or mRNA. The gene may also code for Rybosomal RNA (rRNA), transfer RNA (tRNA), or a ribozyme.