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VICBiologyQuick questions
Unit 3: How do cells maintain life?
Quick questions on Gene expression in eukaryotes (transcription, RNA processing, translation): VCE Biology Unit 3
13short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is transcription (nucleus)?Show answer
Initiation. Transcription factors and RNA polymerase II assemble at the promoter region of the gene (a TATA box sits upstream of the start site). The DNA double helix unwinds, exposing the template strand.
What is rNA processing (nucleus)?Show answer
Pre-mRNA undergoes three modifications before it can leave the nucleus.
What is translation (cytosol or rough ER)?Show answer
Initiation. The small ribosomal subunit binds the 5' cap and scans for the first AUG start codon. An initiator tRNA carrying methionine binds with anticodon UAC. The large subunit then joins to form a complete ribosome with three sites: A (aminoacyl), P (peptidyl) and E (exit).
What is initiation?Show answer
Transcription factors and RNA polymerase II assemble at the promoter region of the gene (a TATA box sits upstream of the start site). The DNA double helix unwinds, exposing the template strand.
What is elongation?Show answer
RNA polymerase moves along the template 3' to 5', adding complementary RNA nucleotides to the growing pre-mRNA in the 5' to 3' direction. Pairing follows A with U, T with A, G with C. The newly built pre-mRNA carries the same sequence as the non-template (coding) strand, with U in place of T.
What is termination?Show answer
RNA polymerase reaches a terminator sequence, releases the pre-mRNA, and the DNA re-zips.
What is transcription?Show answer
Pre-mRNA: 5' AUGCCCUAAUGC 3'.
What is processing?Show answer
A 5' cap and 3' poly-A tail are added; introns (none shown here) would be spliced out.
What is translation?Show answer
AUG (Met, start), CCC (Pro), UAA (stop). The ribosome releases a two-amino-acid peptide (Met-Pro). Note that real proteins are much longer; this example just shows codon reading.
What is saying transcription happens at the ribosome?Show answer
It happens at the gene in the nucleus. Translation happens at the ribosome in the cytosol.
What is mixing up codons and anticodons?Show answer
Codons are on mRNA; anticodons are on tRNA. They are complementary and antiparallel.
What is reading the template strand 5' to 3'?Show answer
RNA polymerase reads the template 3' to 5' and synthesises RNA 5' to 3'.
What is forgetting that processing is eukaryote-specific?Show answer
Prokaryotes do not splice or cap mRNA; transcription and translation are coupled in the cytoplasm.