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
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

10. Transcription

RNA Interference

Genetics

10. Transcription

RNA Interference

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1:21 minutes

Problem 29

Textbook Question

RNAi is currently being tested as a therapeutic tool for genetic diseases and other conditions. Consider the following: cystic fibrosis caused by loss of function of the CFTR gene, HIV infection, and cancer caused by hyperactivity of a growth factor receptor. Which of these may be treatable by RNAi, and which not? Explain your reasoning.

Verified step by step guidance

Step 1: Understand the mechanism of RNA interference (RNAi). RNAi works by targeting and degrading specific messenger RNA (mRNA) molecules, thereby reducing or silencing the expression of particular genes. This means RNAi is effective in conditions where reducing or silencing a gene's expression can be beneficial.

Step 2: Analyze cystic fibrosis, which is caused by loss of function mutations in the CFTR gene. Since RNAi reduces gene expression, it would not be helpful here because the problem is insufficient or nonfunctional CFTR protein. RNAi cannot restore or increase gene function; it only decreases gene expression.

Step 3: Consider HIV infection. HIV relies on viral RNA and proteins to replicate. RNAi can be designed to target viral RNA sequences, potentially reducing viral replication. Therefore, RNAi may be a useful therapeutic tool against HIV by silencing viral genes.

Step 4: Examine cancer caused by hyperactivity of a growth factor receptor. In this case, the problem is excessive expression or activity of a gene. RNAi can target the mRNA of the overactive receptor, reducing its expression and potentially slowing cancer progression. Thus, RNAi may be effective here.

Step 5: Summarize the reasoning: RNAi is suitable for conditions caused by overexpression or presence of harmful RNA (like HIV or hyperactive receptors in cancer) but not for diseases caused by loss of gene function (like cystic fibrosis), where gene expression needs to be restored or enhanced rather than suppressed.

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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 small RNA molecules inhibit gene expression by degrading target mRNA or blocking its translation. It is effective in silencing genes that are overexpressed or harmful, making it a potential therapeutic tool for conditions caused by gene overactivity.

Loss-of-Function vs. Gain-of-Function Mutations

Loss-of-function mutations result in reduced or absent protein activity, while gain-of-function mutations cause increased or new protein activity. RNAi can target and reduce harmful gene products in gain-of-function cases but cannot restore function lost due to gene inactivation.

Therapeutic Applications of RNAi in Genetic Diseases

RNAi is suitable for diseases where reducing harmful gene expression is beneficial, such as viral infections or cancers driven by overactive genes. However, it is ineffective for diseases like cystic fibrosis caused by gene loss, as RNAi cannot replace or restore missing gene function.

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Related Practice

Textbook Question

RNAi may be directed by small interfering RNAs (siRNAs) or microRNAs (miRNAs); how are these similar, and how are they different?

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Textbook Question

miRNAs target endogenous mRNAs in a sequence-specific manner. Explain, conceptually, how one might identify potential mRNA targets for a given miRNA if you only know the sequence of the miRNA and the sequence of all mRNAs in a cell or tissue of interest.

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Textbook Question

In principle, RNAi may be used to fight viral infection. How might this work?

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Textbook Question

While miRNA response elements (MREs) may be located anywhere within an mRNA, they are most often found outside the coding region in the 5' or 3' UTR. Explain why this is likely the case given that miRNAs often target more than one mRNA.

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Textbook Question

Explain how the expression of a single gene can be quickly, efficiently, and specifically shut down at the transcriptional, posttranscriptional, and posttranslational stages through the coordinated expression of a transcriptional repressor, an miRNA, and a ubiquitin ligase.

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Multiple Choice

The term RNAi stands for which of the following?

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Multiple Choice

Which molecule is first folded into a hairpin structure during the mechanism of RNA interference?

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Multiple Choice

Which of the following steps is common to the processing of both miRNAs and siRNAs?

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