Ch. 16 - Regulation of Gene Expression in Eukaryotes
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
Chapter 16, Problem 15
The regulation of mRNA decay relies heavily upon deadenylases and decapping enzymes. Explain how these classes of enzymes are critical to initiating mRNA decay.
Verified step by step guidance1
Begin by understanding that mRNA decay is a crucial process for regulating gene expression by controlling the lifespan of mRNA molecules in the cell.
Recognize that deadenylases are enzymes that shorten the poly(A) tail at the 3' end of the mRNA, which is a key initial step in mRNA decay because the poly(A) tail protects mRNA from degradation and aids in translation.
Note that once the poly(A) tail is sufficiently shortened by deadenylases, the mRNA becomes more vulnerable to decay mechanisms, signaling that the mRNA is ready for further degradation.
Understand that decapping enzymes remove the 5' cap structure of the mRNA, which normally protects the mRNA from exonucleases and is essential for translation initiation.
Realize that removal of the 5' cap by decapping enzymes exposes the mRNA to 5' to 3' exonucleases, thereby committing the mRNA to rapid degradation and effectively initiating the decay process.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
mRNA Decay Pathways
mRNA decay is a cellular process that controls gene expression by degrading messenger RNA molecules. It ensures that mRNAs do not persist longer than needed, allowing cells to regulate protein synthesis dynamically. The decay process typically begins with shortening of the poly(A) tail, followed by removal of the 5' cap, leading to exonucleolytic degradation.
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Repair Pathways
Role of Deadenylases
Deadenylases are enzymes that shorten the poly(A) tail at the 3' end of mRNA. This deadenylation is often the first and rate-limiting step in mRNA decay, destabilizing the mRNA and making it more susceptible to further degradation. By removing the poly(A) tail, deadenylases trigger downstream decay mechanisms.
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Function of Decapping Enzymes
Decapping enzymes remove the 5' cap structure of mRNA, which protects the transcript from exonucleases. Once the cap is removed, the mRNA becomes vulnerable to 5' to 3' exonucleolytic degradation. Decapping is a critical step that commits the mRNA to rapid decay, following deadenylation.
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Related Practice