Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 40m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 20m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 52m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 57m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

11. Cell Division

Cell Cycle Regulation

General Biology

11. Cell Division

Cell Cycle Regulation

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0:51 minutes

Problem 4`

Textbook Question

The decline of MPF activity at the end of mitosis is due to
a. 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 the role of MPF (Maturation Promoting Factor) in the cell cycle. MPF is a complex of cyclin and Cdk (Cyclin-dependent kinase) that is crucial for the progression of cells from G2 phase to mitosis.

Recognize that MPF activity is regulated by the concentration of cyclin. Cyclin binds to Cdk, activating it, which in turn promotes mitosis.

Identify that at the end of mitosis, MPF activity must decline to allow the cell to exit mitosis and enter the next phase of the cell cycle.

Learn that the decline in MPF activity is primarily due to the degradation of cyclin. Cyclin is tagged for destruction by ubiquitination, leading to its breakdown by proteasomes.

Conclude that the degradation of cyclin results in the inactivation of Cdk, as Cdk requires cyclin to be active. Therefore, the correct answer is related to the degradation of cyclin.

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Key Concepts

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

MPF (Maturation Promoting Factor)

MPF is a complex of cyclin and cyclin-dependent kinase (Cdk) that plays a crucial role in regulating the cell cycle, particularly the transition from G2 phase to mitosis. Its activity is essential for the initiation of mitosis, and it is regulated by the levels of cyclin and the phosphorylation state of Cdk.

Cyclin

Cyclins are proteins that control the progression of cells through the cell cycle by activating Cdks. Cyclin levels fluctuate throughout the cell cycle, with specific cyclins being synthesized and degraded at different stages, which in turn regulates the activity of Cdks and the timing of cell cycle events.

Cyclin Degradation

The degradation of cyclin is a key mechanism for regulating MPF activity. At the end of mitosis, cyclin is targeted for degradation by the ubiquitin-proteasome pathway, leading to a decrease in MPF activity. This degradation is crucial for the exit from mitosis and the transition to the next phase of the cell cycle.