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

Cell Cycle Regulation

Anatomy & Physiology

3. Energy & Cell Processes

Cell Cycle Regulation

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Problem 4

Textbook Question

The decline of MPF activity at the end of mitosis is due toa. the destruction of the protein kinase Cdk.b. decreased synthesis of Cdk.c. the degradation of cyclin.d. the accumulation of cyclin.

Verified step by step guidance

Understand that MPF (Maturation Promoting Factor) is a complex of cyclin and Cdk (cyclin-dependent kinase) that regulates the cell cycle.

Recognize that the activity of MPF is dependent on the presence of cyclin, which binds to Cdk to activate it.

Recall that at the end of mitosis, the cell needs to transition to the next phase, which requires the inactivation of MPF.

Consider that the degradation of cyclin leads to the inactivation of MPF, as Cdk alone is inactive without cyclin.

Conclude that the decline of MPF activity at the end of mitosis is due to the degradation of cyclin, which is option c.

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Key Concepts

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

Maturation Promoting Factor (MPF)

Maturation Promoting Factor (MPF) is a complex of cyclin and cyclin-dependent kinase (Cdk) that regulates the cell cycle, particularly the transition from G2 phase to mitosis. MPF activity is crucial for the initiation of mitosis, and its levels fluctuate throughout the cell cycle, peaking during mitosis.

Cyclin Degradation

Cyclins are regulatory proteins whose levels rise and fall throughout the cell cycle. At the end of mitosis, cyclins are targeted for degradation, leading to a decrease in MPF activity. This degradation is essential for the exit from mitosis and the progression into the next cell cycle phase.

Cyclin-Dependent Kinase (Cdk)

Cyclin-dependent kinases (Cdks) are enzymes that, when activated by binding to cyclins, phosphorylate target proteins to drive the cell cycle forward. The activity of Cdks is tightly regulated by the availability of cyclins and their degradation, which is critical for ensuring proper cell cycle progression and preventing uncontrolled cell division.