Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

3. Energy & Cell Processes

Central Dogma

Anatomy & Physiology

3. Energy & Cell Processes

Central Dogma

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Problem L3A2

Textbook Question

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?

Verified step by step guidance

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.

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.

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.