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Transcription

Transcription is the copying of DNA into complementary mRNA.

Transcription is an important step in protein synthesis and occurs inside the nucleus. It can be broken down into three steps:

  1. Initiation: Enzymes such as RNA polymerase (RNAP) bind to the promoter region of the gene.

    A small section of the DNA is unwound, exposing the bases for transcription. Only one strand of the DNA is transcribed and used as a template for protein synthesis.

  2. Elongation: Complementary RNA nucleotides assemble alongside the DNA template. RNA polymerase catalyses the formation of phosphodiester bonds between the RNA nucleotides.

  3. Termination: Transcription ends when RNA polymerase reaches the terminator sequence, a section of non-coding DNA positioned just downstream of the gene.

    The terminator sequence causes the polymerase to unbind from the DNA. A single strand of mRNA is released.