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

Phases of Mitosis

Anatomy & Physiology

3. Energy & Cell Processes

Phases of Mitosis

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Problem 6

Textbook Question

What evidence suggests that during anaphase, kinetochore microtubules shorten at the kinetochore?

Verified step by step guidance

1. Anaphase is a stage in mitosis and meiosis where the chromosomes separate. Each chromosome is attached to a structure called a kinetochore, which is connected to the spindle fibers (microtubules).

2. The evidence that suggests kinetochore microtubules shorten at the kinetochore during anaphase comes from several observations. One of the most compelling pieces of evidence is the movement of chromosomes towards the poles of the cell during anaphase. This movement is consistent with the shortening of the microtubules at the kinetochore end.

3. Another piece of evidence comes from experiments where fluorescent markers are used to label the microtubules. Under a microscope, these markers can be seen to move towards the poles of the cell during anaphase, suggesting that the microtubules are shortening from the kinetochore end.

4. Additionally, electron microscopy has shown that during anaphase, the kinetochore remains attached to the end of the microtubule, even as it shortens. This suggests that the microtubule is shortening from the kinetochore end, rather than the pole end.

5. Finally, biochemical studies have shown that the protein complexes that make up the kinetochore can catalyze the disassembly of microtubules, providing a mechanism for how the microtubules could be shortening at the kinetochore end during anaphase.

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Key Concepts

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

Anaphase

Anaphase is a stage in mitosis where sister chromatids are separated and pulled toward opposite poles of the cell. This process is crucial for ensuring that each daughter cell receives an identical set of chromosomes. During anaphase, the cohesin proteins that hold the sister chromatids together are cleaved, allowing them to move apart.

Kinetochore Microtubules

Kinetochore microtubules are specialized structures that connect the spindle apparatus to the kinetochore, a protein complex assembled on the centromere of each chromosome. These microtubules play a vital role in chromosome movement during cell division by exerting forces that pull the chromatids apart. Their dynamic nature allows them to grow and shrink, facilitating the separation process.

Microtubule Shortening

Microtubule shortening refers to the process by which microtubules lose tubulin subunits, leading to a decrease in their length. In the context of anaphase, evidence suggests that this shortening occurs at the kinetochore, contributing to the movement of chromatids toward the poles. This process is driven by the depolymerization of tubulin, which is essential for the effective segregation of chromosomes.