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Ch. 12 - The Genetic Code and Transcription
Klug - Essentials of Genetics 10th Edition
Klug10th EditionEssentials of GeneticsISBN: 9780135588789Not the one you use?Change textbook
All textbooksKlug 10th EditionCh. 12 - The Genetic Code and TranscriptionProblem 24b
Chapter 12, Problem 24b

Recent observations indicate that alternative splicing is a common way for eukaryotes to expand their repertoire of gene functions. Studies indicate that approximately 50 percent of human genes exhibit alternative splicing and approximately 15 percent of disease-causing mutations involve aberrant alternative splicing. Different tissues show remarkably different frequencies of alternative splicing, with the brain accounting for approximately 18 percent of such events [Xu et al. (2002). Nucl. Acids Res. 30:3754–3766].
Why might some tissues engage in more alternative splicing than others?

Verified step by step guidance
1
Understand that alternative splicing allows a single gene to produce multiple mRNA variants, leading to different protein isoforms with potentially diverse functions.
Recognize that tissues with complex functions, such as the brain, require a greater diversity of proteins to support specialized cellular activities and signaling pathways.
Consider that the regulation of alternative splicing is controlled by tissue-specific expression of splicing factors and regulatory proteins, which can vary widely between tissues.
Acknowledge that tissues with higher cellular complexity or functional demands may have evolved mechanisms to increase proteomic diversity through more frequent alternative splicing events.
Summarize that the variation in alternative splicing frequency among tissues reflects their differing biological roles and the need for tailored protein functions to meet those roles.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alternative Splicing Mechanism

Alternative splicing is a process during gene expression where a single pre-mRNA transcript can be spliced in multiple ways to produce different mature mRNA variants. This allows one gene to encode multiple protein isoforms, increasing proteomic diversity without increasing gene number.
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Tissue-Specific Gene Expression

Different tissues express unique sets of splicing factors and regulatory proteins that influence how pre-mRNA is spliced. This tissue-specific regulation leads to variations in alternative splicing patterns, enabling cells to produce proteins tailored to their functional needs.
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Functional Complexity and Cellular Demand

Tissues with complex functions, like the brain, require a diverse array of proteins to support specialized activities such as signaling and plasticity. Higher rates of alternative splicing in these tissues provide the necessary protein diversity to meet these complex physiological demands.
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Related Practice
Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

__________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met -Cys-Ile-Val-Val-Val-Gln-His

______________________________________________

Use this information to answer the following questions:

The wild-type RNA consists of nine triplets. What is the role of the ninth triplet?

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Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

___________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-Hi

___________________________________________________

Use this information to answer the following questions:

Of the first eight wild-type triplets, which, if any, can you determine specifically from an analysis of the mutant proteins? In each case, explain why or why not.

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Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

___________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met -Cys-Ile-Val-Val-Val-Gln-His

___________________________________________________

Use this information to answer the following questions:

Another mutation (mutant 4) is isolated. Its amino acid sequence is unchanged from the wild type, but the mutant cells produce abnormally low amounts of the wild-type proteins. As specifically as you can, predict where this mutation exists in the gene.

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