Molecular biology
⏱ ~3-min readAceMark Guide
What this topic is really about
RNA polymerase catalyzes the synthesis of a complementary RNA strand using a DNA template during transcription, producing mRNA that will be translated into protein. DNA polymerase, by contrast, copies DNA during replication and cannot incorporate ribonucleotides, so it is not the enzyme that generates mRNA; reverse transcriptase makes DNA from RNA, and helicase merely unwinds DNA strands.
Ribosomes translate protein sequences by reading the mRNA template three nucleotides (a codon) at a time, matching each codon with the appropriate aminoacyl‑tRNA. DNA is the substrate for transcription, not translation, so answer A is wrong; tRNA alone cannot encode a protein, and lipids are not nucleic acids, eliminating options C and D.
See the mechanism
RNA polymerase catalyzes the synthesis of a complementary RNA strand using a DNA template during transcription, producing mRNA that will be translated into protein. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.
An exam-style question, fully explained
The enzyme that synthesises mRNA from a DNA template is:
- Identify what the question tests: The enzyme that synthesises mRNA from a DNA template is:.
- RNA polymerase catalyzes the synthesis of a complementary RNA strand using a DNA template during transcription, producing mRNA that will be translated into protein.
- DNA polymerase, by contrast, copies DNA during replication and cannot incorporate ribonucleotides, so it is not the enzyme that generates mRNA; reverse transcriptase makes DNA from RNA, and helicase merely unwinds DNA strands.
Traps the examiner sets
- DNA polymerase, by contrast, copies DNA during replication and cannot incorporate ribonucleotides, so it is not the enzyme that generates mRNA; reverse transcriptase makes DNA from RNA, and helicase merely unwinds DNA...
- DNA is the substrate for transcription, not translation, so answer A is wrong; tRNA alone cannot encode a protein, and lipids are not nucleic acids, eliminating options C and D.
- They do not cut at random positions, which allows researchers to make predictable genomic cuts for molecular cloning.
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