Remember: The making of mRNA is called transcription. mRNA is important because it can leave the nucleus, unlike DNA, so cells can transcribe different RNA's in different cells to make different proteins (cell specification). Transcription takes place in the nucleus of a cell and is made whenever proteins are needed.
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There are 3 basic steps of making mRNA:
- Initiation
- Elongation
- Termination
1. Initiation
- The enzyme RNA polymerase binds to the DNA strand and unzips one gene
2. Elongation
- RNA polymerase helps free RNA nucleotide base pairs with one strand of the DNA molecule (called a template strand)
- Adenine (A) pairs with uracil (U) and guanine (g) pairs with cytosine (C)
- Uracil (U) replaces thymine (T)
- Ribose sugar is used instead of deoxyribose sugar
3. Termination
- RNA polymerase reaches a stop sequence on the DNA and releases
- mRNA strand is finished and released
- DNA zips back up