Friday 26 April 2024

New video posted: Transcription - making proteins from DNA - the mRNA

This is the first of two videos on how cells make proteins using DNA. The second video looks at how we go from messenger RNA (mRNA) to protein - Translation - making proteins from DNA - decoding mRNA to make the protein

In this video, I will guide you through the first steps in the process of producing RNA from DNA, also known as transcription. In the next video, we will take the next step and examine how we produce the protein from mRNA.

The video looks at the five steps of mRNA production:

  • initiation — activators bind upstream, often thousands of bases upstream, of the gene. The activators assemble the required proteins (the mediator, chromatin remodelling complex, the RNA polymerase and transcription factors) at the TATA box, which is a DNA sequence close to the gene
  • production — DNA is transcribed into the pre-messenger RNA
  • five prime capping — the five prime end of the pre-messenger RNA is capped with some modified nucleotides
  • splicing — introns are spliced out of the pre-messenger RNA to leave just the exons (exons provide the sequence for the protein)
  • three prime polyadenylation — addition of a polyadenylated tail to the three prime end of the pre-messenger RNA to give the final mature messenger RNA molecule

The video not only looks at mRNA production but also introduces the idea of non-coding RNA (ncRNA), which are RNA molecules that do not encode proteins. ncRNAs are essential in regulating gene expression and various cellular processes. For example:

  • transfer RNA (tRNA) — involved in protein synthesis
  • ribosomal RNA (rRNA) — involved in protein synthesis
  • microRNA (miRNA) — control gene expression
  • small interfering RNA (siRNA) — control gene expression 
  • long non-coding RNA (lncRNA) — diverse functions
  • circular RNA (circRNA) — gene regulation
  • Piwi-interacting RNA (piRNA) — genome protection
  • enhancer RNAs (eRNAs) — modulate gene activity
Finally, I cover how to write out DNA sequences, the means of the terms sense and antisense strands, and what we mean by upstream and downstream when talking about DNA and RNA molecules.

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Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

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