Genes and gene expression — A/L Biology

How do I practise Genes and gene expression?

1 question with a worked solution

1. If the DNA template strand has the base sequence 3'-TAC GGA CTT ACT-5', what is the corresponding mRNA codon sequence synthesized during transcription?
   1. A) 5'-UAC GGA CUU ACU-3'
   2. B) 5'-ATG CCT GAA TGA-3'
   3. C) 3'-AUG CCU GAA UGA-5'
   4. D) 5'-AUG CCU GAA UGA-3'
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   Correct answer: D) 5'-AUG CCU GAA UGA-3'

   Transcription produces an antiparallel, complementary RNA strand where A pairs with U, T pairs with A, and G/C pair mutually. 3'-TAC GGA CTT ACT-5' transcribes to 5'-AUG CCU GAA UGA-3'.

   Show worked solution

   Step 1: Note template polarity: 3' to 5'. Step 2: mRNA strand runs antiparallel: 5' to 3'. Step 3: Base pairing: T→A, A→U, C→G, G→C, G→C, A→U, C→G, T→A, T→A, A→U, C→G, T→A. Step 4: Assembled mRNA: 5'-AUG CCU GAA UGA-3'. Answer: 5'-AUG CCU GAA UGA-3'.
   Modelled on: the A/L Biology examination pattern

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Where does Genes and gene expression fit in the syllabus?

Year 1 · Term 2