Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
10. Transcription
RNA Interference
Problem 11
Textbook Question
In 1998, future Nobel laureates Andrew Fire and Craig Mello, and colleagues, published an article in Nature entitled, 'Potent and Specific Genetic Interference by Double-Stranded RNA in Caenorhabditis elegans.' Explain how RNAi is both 'potent and specific.'

1
Understand that RNA interference (RNAi) is a biological process where double-stranded RNA (dsRNA) molecules inhibit gene expression by causing the degradation of specific messenger RNA (mRNA) molecules.
Recognize that RNAi is 'potent' because even small amounts of dsRNA can trigger a strong gene-silencing effect, efficiently reducing the target mRNA levels and thus protein production.
Note that RNAi is 'specific' because the dsRNA sequence is complementary to the target mRNA sequence, allowing the RNA-induced silencing complex (RISC) to precisely recognize and degrade only the matching mRNA without affecting other genes.
Recall that the specificity arises from base-pairing rules, where the small interfering RNA (siRNA) guides RISC to the exact mRNA sequence through Watson-Crick base pairing, ensuring targeted gene silencing.
Summarize that the combination of high efficiency in silencing (potency) and precise sequence recognition (specificity) makes RNAi a powerful tool for gene regulation and functional genomics studies.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
RNA Interference (RNAi) Mechanism
RNAi is a biological process where double-stranded RNA (dsRNA) triggers the degradation of complementary messenger RNA (mRNA), effectively silencing specific genes. This mechanism involves the enzyme Dicer cutting dsRNA into small interfering RNAs (siRNAs), which guide the RNA-induced silencing complex (RISC) to target and degrade matching mRNA sequences.
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Specificity of RNAi
RNAi is highly specific because the siRNAs produced are complementary to particular mRNA sequences. This base-pairing ensures that only mRNAs with matching sequences are targeted for degradation, allowing precise gene silencing without affecting unrelated genes.
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Potency of RNAi
RNAi is potent because a small amount of dsRNA can trigger the degradation of many mRNA molecules, amplifying the gene-silencing effect. This amplification and the catalytic nature of the RISC complex enable efficient and robust suppression of gene expression.
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Multiple Choice
In general, mRNAs targeted by siRNAs are cleaved by RISC because:
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