M phase

Definition

The M phase, or mitotic phase, is a stage in the cell cycle where cell division occurs, resulting in two daughter cells. This phase encompasses both mitosis, the division of the nucleus, and cytokinesis, the division of the cytoplasm. Understanding this phase is crucial for recognizing how cells replicate and how they can be affected by various factors, including radiation exposure and treatment strategies.

5 Must Know Facts For Your Next Test

1. The M phase is typically the shortest phase of the cell cycle, usually lasting only a few hours.
2. During mitosis, chromosomes condense and align at the cell's equatorial plane before being pulled apart into separate nuclei.
3. Cytokinesis can occur simultaneously with telophase, marking the end of the M phase and completion of cell division.
4. Cells are most sensitive to radiation during the M phase, making it crucial for radiation therapy considerations.
5. M phase can be disrupted by various factors such as DNA damage or chemical agents, leading to potential cell death or malfunction.

Review Questions

• How does the M phase fit into the overall structure of the cell cycle and what key processes occur during this phase?
  • The M phase is one of the four main phases of the cell cycle, which also includes G1, S, and G2 phases. It involves critical processes like mitosis, where the duplicated chromosomes are separated into two nuclei, and cytokinesis, where the cytoplasm divides to form two new cells. This phase is essential for cellular reproduction and allows organisms to grow and repair tissues.
• Discuss how variation in radiosensitivity throughout the cell cycle impacts treatment strategies targeting the M phase.
  • Cells exhibit varying levels of radiosensitivity at different phases of the cell cycle, with the M phase being particularly sensitive to radiation. This means that when planning radiation therapy, healthcare professionals aim to target tumors when they are most likely in this vulnerable state to maximize damage to cancerous cells while sparing normal tissue. By timing treatment to coincide with high sensitivity periods, efficacy can be improved.
• Evaluate how understanding the M phase can lead to improved approaches in developing therapies for cancer treatment.
  • A deep understanding of the M phase allows researchers to design more effective cancer therapies by targeting specific vulnerabilities during cell division. For example, drugs that disrupt mitotic spindle formation can selectively kill rapidly dividing cancer cells. By enhancing our knowledge of cellular behavior during this critical phase, we can optimize therapeutic strategies that exploit these weaknesses to achieve better outcomes in cancer treatment.

Related terms

Mitosis: The process during the M phase where a single cell divides its nucleus and genetic material into two identical nuclei.

Cytokinesis: The final step of cell division that follows mitosis, where the cytoplasm divides, resulting in two distinct daughter cells.

Cell Cycle Checkpoints: Control mechanisms in the cell cycle that ensure proper division and repair any DNA damage before proceeding to the next phase.