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Ch. 3 The Cell
Amerman - Human Anatomy & Physiology 2nd Edition
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksAmerman 2nd EditionCh. 3 The CellProblem L3A2
Chapter 3, Problem L3A2

A popular science fiction program once had an episode that featured an 'intron virus' that 'turned on' the introns in the genes, causing the synthesis of abnormal proteins. The episode may have been entertaining, but its premise had a large flaw about the nature of introns. What was the flaw?

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1
Understand the role of introns in gene expression: Introns are non-coding sequences within a gene that are removed during RNA splicing. They do not directly code for proteins, as they are excised from the pre-mRNA before translation.
Clarify the concept of RNA splicing: During transcription, a gene produces pre-mRNA, which contains both exons (coding regions) and introns (non-coding regions). The introns are removed by spliceosomes, leaving only the exons to form the mature mRNA that is translated into a protein.
Identify the flaw in the premise: The idea that introns could be 'turned on' to synthesize abnormal proteins is flawed because introns do not contain coding sequences for proteins. They are regulatory or non-functional sequences that are not translated into proteins under normal circumstances.
Explain why abnormal protein synthesis would not occur: Since introns are removed during RNA processing, they do not contribute to the sequence of the mature mRNA. Therefore, they cannot directly influence the synthesis of proteins, whether normal or abnormal.
Conclude with the scientific basis: The episode's premise misunderstands the fundamental biology of gene expression. Introns are not functional coding units, and their activation would not lead to protein synthesis, as proteins are derived only from the coding exons in the mature mRNA.

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Key Concepts

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

Introns

Introns are non-coding sequences of DNA that are found within genes. They are transcribed into precursor mRNA but are removed during RNA splicing before translation into proteins. Understanding the role of introns is crucial, as they do not directly code for proteins but can influence gene expression and the regulation of alternative splicing.
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2) RNA Splicing Creates Mature mRNA

Gene Expression Regulation

Gene expression regulation refers to the mechanisms that control the timing and amount of gene product (protein) produced in a cell. This process involves various elements, including enhancers, silencers, and transcription factors, which interact with both coding and non-coding regions of DNA, including introns, to modulate gene activity rather than simply 'turning on' introns.
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Types of Genes Regulating Cell Growth

Protein Synthesis

Protein synthesis is the biological process through which cells generate new proteins, involving transcription of DNA to mRNA and translation of mRNA to amino acid chains. The premise of the episode incorrectly suggests that activating introns directly leads to abnormal protein synthesis, overlooking the complex regulatory mechanisms that govern how proteins are made from coding sequences.
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Proteins
Related Practice
Textbook Question

A patient is admitted to the hospital and given intravenous (IV) fluids. Four hours later, the patient complains that his mouth and eyes feel dry. You notice that he displays signs of dehydration, and when you check his IV, you see that he was given the wrong kind of fluids. Were these fluids likely hypotonic, isotonic, or hypertonic? Explain.

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Textbook Question

A hypothetical poison prevents transcription factors from binding to the gene for tubulin proteins. What impact would this have on mitosis, and why?

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Textbook Question

Epithelial cells of the kidneys have pumps that drive the transcellular transport of sodium ions.

The movement of sodium ions drives the transcellular transport of water. Explain why water follows sodium. (Connects to Chapter 3)

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Textbook Question

What effect would the hypothetical poison of question 3 have on other functions of the cell? Explain.

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Textbook Question

What are the two fluid compartments in the body, and how are they kept separate?

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Textbook Question

Write a single sentence, using no more than 25 words, to summarize each of the following cellular processes:

Mitosis

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