Gene transcription: Difference between revisions
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When a gene is copied from its [[DNA|DNA]] form to its [[RNA|RNA]] form<ref>https://en.wikipedia.org/wiki/Transcription_(biology)</ref>. | When a gene is copied from its [[DNA|DNA]] form to its [[RNA|RNA]] form<ref>https://en.wikipedia.org/wiki/Transcription_(biology)</ref>. The [[Antisense strand|antisense strand]] of DNA acts as a template strand and is used by [[RNA polymerase|RNA polymerases]] to synthesise mRNA . In eukaryotes, the mRNA produced in transcription is modified through the addition of a polyA tail and 5' cap. The modified [[MRNA|mRNA]] can then be used in [[Translation|translation]] at the [[Ribosome|ribosomes]] by [[TRNA|tRNA]] to synthesise a [[Polypeptide|polypeptide]], allowing the gene to be expressed<ref>Khan Academy. Overview of transcription: in transcription, the DNA sequence of a gene is transcribed (copied out) to make an RNA molecule. Date published unknown [Accessed 5/12/18]; Available from: https://www.khanacademy.org/science/biology/gene-expression-central-dogma/transcription-of-dna-into-rna/a/overview-of-transcription</ref>. | ||
=== References === | The process of transcription involves three major stages: initiation, elongation and termination. During initiation, RNA polymerase enzyme binds to the [[Promoter|promotor sequence]] upstream of the gene on the antisense strand, this is the closed complex. Binding of the RNA polymerase to the promoter causes local denaturation of the DNA so it starts to unwind, this is known as the open complex. The next stage of transcription is elongation where the strand of mRNA is synthesised. RNA polymerase synthesises mRNA using RNA [[Nucleotides|nucleotides]] and the principles of [[Complementary base pairing|complementary base pairing]], meaning that the mRNA synthesised is identical to the sense strand but with [[Uracil|uracil]] instead of [[Thymine|thymine]]. Transcription stops when the RNA polymerase [[Enzyme|enzyme reaches]] a [[Terminator sequence|terminator]] sequence, the mRNA then detaches from the DNA<ref>Bozeman Science. Steps of Genetic Transcription. Date published unknown [Accessed 5/12/18]; Available from: https://courses.lumenlearning.com/wm-biology1/chapter/reading-steps-of-genetic-transcription/</ref>. | ||
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[[Image:Transcription for WIKI.png|Three stages of transcription: Initiation, elongation and termination]]<br> | |||
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=== References === | |||
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Latest revision as of 18:43, 5 December 2018
When a gene is copied from its DNA form to its RNA form[1]. The antisense strand of DNA acts as a template strand and is used by RNA polymerases to synthesise mRNA . In eukaryotes, the mRNA produced in transcription is modified through the addition of a polyA tail and 5' cap. The modified mRNA can then be used in translation at the ribosomes by tRNA to synthesise a polypeptide, allowing the gene to be expressed[2].
The process of transcription involves three major stages: initiation, elongation and termination. During initiation, RNA polymerase enzyme binds to the promotor sequence upstream of the gene on the antisense strand, this is the closed complex. Binding of the RNA polymerase to the promoter causes local denaturation of the DNA so it starts to unwind, this is known as the open complex. The next stage of transcription is elongation where the strand of mRNA is synthesised. RNA polymerase synthesises mRNA using RNA nucleotides and the principles of complementary base pairing, meaning that the mRNA synthesised is identical to the sense strand but with uracil instead of thymine. Transcription stops when the RNA polymerase enzyme reaches a terminator sequence, the mRNA then detaches from the DNA[3].
References
- ↑ https://en.wikipedia.org/wiki/Transcription_(biology)
- ↑ Khan Academy. Overview of transcription: in transcription, the DNA sequence of a gene is transcribed (copied out) to make an RNA molecule. Date published unknown [Accessed 5/12/18]; Available from: https://www.khanacademy.org/science/biology/gene-expression-central-dogma/transcription-of-dna-into-rna/a/overview-of-transcription
- ↑ Bozeman Science. Steps of Genetic Transcription. Date published unknown [Accessed 5/12/18]; Available from: https://courses.lumenlearning.com/wm-biology1/chapter/reading-steps-of-genetic-transcription/