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Describe how mRNA is formed by transcription in eukaryotes - AQA - A-Level Biology - Question 10 - 2020 - Paper 1
Question 10
Describe how mRNA is formed by transcription in eukaryotes. 1. Hydrogen bonds between DNA bases break. 2. Only one DNA strand acts as a template. 3. Free RNA nucleo... show full transcript
Worked Solution & Example Answer:Describe how mRNA is formed by transcription in eukaryotes - AQA - A-Level Biology - Question 10 - 2020 - Paper 1
Step 1
Describe how mRNA is formed by transcription in eukaryotes.
Answer
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Transcription begins when hydrogen bonds between the bases of the DNA break, allowing for one strand to become accessible as a template.
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Only one DNA strand, referred to as the template strand, will serve in the process of transcription.
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Free RNA nucleotides then align themselves along the template strand by complementary base pairing, where adenine (A) pairs with uracil (U) rather than thymine (T).
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This process is facilitated by the enzyme RNA polymerase, which catalyzes the joining of adjacent RNA nucleotides.
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As the RNA polymerase moves along the DNA, it forms phosphodiester bonds between the nucleotides, creating a growing mRNA strand.
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After transcription, the primary RNA transcript, called pre-mRNA, undergoes splicing where introns are removed and exons are joined to form mature mRNA, which then exits the nucleus.