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

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Anatomy & Physiology

3. Energy & Cell Processes

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Problem 13

Textbook Question

Toxins like αα-amanitin are used for research in much the same way as null mutants (Chapter 16)—to disrupt a process and see what happens when it no longer works. Researchers examined the ability of αα-amanitin to inhibit different RNA polymerases. They purified RNA polymerases I, II, and III from rat liver, incubated the enzymes with different concentrations of αα-amanitin, and then tested their activity. The results of this experiment are shown here. These findings suggest that cells treated with αα-amanitin will have a reduced level of:a. tRNAsb. rRNAsc. snRNAsd. mRNAs

Verified step by step guidance

Identify the role of each RNA polymerase: RNA polymerase I synthesizes rRNA, RNA polymerase II synthesizes mRNA and snRNA, and RNA polymerase III synthesizes tRNA and some rRNA.

Understand the effect of αα-amanitin: It is known to specifically inhibit RNA polymerase II.

Determine which RNA products will be affected: Since αα-amanitin inhibits RNA polymerase II, the synthesis of mRNA and snRNA will be reduced.

Analyze the options given: a. tRNAs, b. rRNAs, c. snRNAs, d. mRNAs.

Conclude which RNA level will be reduced: Based on the inhibition of RNA polymerase II, the levels of mRNAs and snRNAs will be reduced.

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Key Concepts

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

RNA Polymerases

RNA polymerases are enzymes responsible for synthesizing RNA from a DNA template. In eukaryotic cells, there are three main types: RNA polymerase I synthesizes rRNA (ribosomal RNA), RNA polymerase II synthesizes mRNA (messenger RNA) and some snRNA (small nuclear RNA), and RNA polymerase III synthesizes tRNA (transfer RNA) and other small RNAs. Understanding the specific functions of these polymerases is crucial for interpreting the effects of inhibitors like αα-amanitin.

αα-amanitin

αα-amanitin is a cyclic peptide toxin derived from the Amanita phalloides mushroom, known for its ability to selectively inhibit RNA polymerase II. This inhibition leads to a decrease in mRNA synthesis, which is critical for protein production in cells. By understanding how αα-amanitin affects different RNA polymerases, researchers can deduce the impact on various RNA types produced in the cell.

Gene Expression Regulation

Gene expression regulation refers to the processes that control the timing and amount of gene expression in cells. This regulation is essential for cellular function and differentiation, as it determines which proteins are produced and when. The inhibition of RNA polymerases by toxins like αα-amanitin disrupts this regulation, leading to reduced levels of specific RNA types, which can be analyzed to understand the broader implications for cellular processes.