Cells and control Study Guide

Cancer arises from fundamental changes within the body's cells that lead to their uncontrolled division. Normally, cell division is a tightly regulated process, essential for growth, repair, and replacement of old or damaged cells. However, in cancer, these regulatory mechanisms fail. This failure is typically due to mutations in genes that control cell growth and division. These mutated cells lose their normal cell cycle checkpoints and begin to divide repeatedly and excessively, forming a mass of cells known as a tumour. This uncontrolled proliferation can lead to serious health issues, as the tumour can invade and damage surrounding tissues, and in some cases, spread to other parts of the body.

Mitosis is a fundamental process of cell division in eukaryotic cells, essential for growth, repair, and asexual reproduction. It is a part of the broader cell cycle, which includes interphase and the mitotic (M) phase. During interphase, the cell prepares for division by growing and replicating its DNA. The M phase encompasses mitosis itself, where the nucleus divides, followed by cytokinesis, the division of the cytoplasm, resulting in two genetically identical daughter cells. The stages of mitosis – prophase, metaphase, anaphase, and telophase – ensure that each new cell receives a complete and identical set of chromosomes. This precise mechanism is crucial for maintaining genetic stability and proper organismal development.