A tumor is an abnormal mass of tissue that forms when cells divide and grow excessively or uncontrollably. Tumors can be benign (non-cancerous) or malignant (cancerous).
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Benign tumors do not invade nearby tissues or spread to other parts of the body. They generally do not pose a significant health risk but can still cause problems depending on their size and location.
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Malignant tumors, on the other hand, can invade surrounding tissues and may spread (metastasize) to other parts of the body through the bloodstream or lymphatic system. Malignant tumors are typically associated with cancer.
Tumors are often a result of mutations in the DNA of cells that disrupt the normal regulatory mechanisms of the cell cycle and mitosis, which is the process of cell division.
Mitosis Quick Check
Mitosis is the process by which a single cell divides to produce two identical daughter cells. Here are the key stages:
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Prophase: Chromatin condenses into visible chromosomes, and the nuclear envelope breaks down. The spindle apparatus begins to form.
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Metaphase: Chromosomes line up along the equatorial plane of the cell, and spindle fibers attach to the centromeres of the chromosomes.
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Anaphase: Sister chromatids are pulled apart and move toward opposite poles of the cell.
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Telophase: Chromatids reach the poles, and the nuclear envelope begins to reform. Chromosomes decondense back into chromatin.
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Cytokinesis: Although not technically a phase of mitosis, this process overlaps with telophase and divides the cytoplasm of the cell, resulting in two separate daughter cells.
Understanding the mitosis process is crucial for comprehending how tumors develop and the role of cell division in cancer biology.