DNA and gene expression
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What is the aligned complement of 5'-A C G-3'?
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3'-T G C-5'.
Complementary bases occupy matching positions on an antiparallel strand.
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Which pairing is correct?
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tRNA: anticodon and amino-acid attachment site.
These features let it act as an adaptor.
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What does DNA ligase do during replication?
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Seal breaks in the sugar-phosphate backbone between fragments.
This completes a continuous strand after fragment synthesis and primer replacement.
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Which enzyme is NOT needed to replicate DNA?
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RNA polymerase
RNA polymerase transcribes genes. Replication uses helicase, DNA polymerase and DNA ligase (with primase for primers).
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Which RNA matches the template 3'-TGA-5'?
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5'-ACU-3'.
The RNA is complementary and antiparallel.
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A DNA template strand reads 3' TAC GCA 5'. Which mRNA is transcribed?
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5' AUG CGU 3'
mRNA is complementary to the template: T to A, A to U, C to G, G to C, running 5' to 3'.
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Which sequence represents the spliced product of exon 1 - intron - exon 2?
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Exon 1 joined to exon 2.
Retained exon sequences are joined in order.
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What directly determines the order in which amino acids are added?
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The order of mRNA codons read by the ribosome.
Codon order directs the amino-acid sequence.
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