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.
Worked Solution & Example Answer:Describe how mRNA is formed by transcription in eukaryotes.
- AQA - A-Level Biology - Question 10 - 2020 - Paper 1
Step 1
1. Hydrogen bonds break
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Answer
During transcription, the hydrogen bonds between the complementary DNA bases break, allowing the DNA strands to separate.
Step 2
2. Template strand
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Answer
Only one strand of the DNA, known as the template strand, is used for the synthesis of mRNA.
Step 3
3. Alignment of RNA nucleotides
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Answer
Free RNA nucleotides align along the template strand, following the rules of complementary base pairing, where adenine (A) pairs with uracil (U) in RNA, and cytosine (C) pairs with guanine (G).
Step 4
4. RNA polymerase action
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RNA polymerase joins the RNA nucleotides together to form a single-stranded mRNA molecule.
Step 5
5. Pre-mRNA processing
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Before the mRNA can be used for translation, it undergoes processing where introns are spliced out and exons are joined, resulting in a mature mRNA molecule.
