Cell Division

Chromosomes Are made of DNA Each chromosome consists of sister chromatids attached at a centromere

Cell Cycle During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each with each of which then begins the cycle again. Interphase – time for growth and regular cell activity. Most of a cells life is spent in Interphase.

Interphase

Introduction to Cell Division

Mitosis The division of somatic or regular cells. Its divided into 4 phases. Remember Interphase is NOT part of Mitosis.

Introduction to Mitosis

Prophase First stage of Mitosis Chromatin condenses into chromosomes Centrioles separate and a spindle fiber begins to form. Nuclear membrane breaks down

Prophase

Metaphase Second Phase of Mitosis Chromosomes line up in the middle of the cell. Each chromosome is connected to a spindle fiber.

Metaphase

Anaphase Third Phase of Mitosis The sister chromatids separate into individual chromosomes and move apart to opposite ends of the cell.

Anaphase

Telophase Fourth and Final Stage of Mitosis Chromosomes gather at opposite ends of the cell and lose their distinct shapes Two new nuclear membranes have formed.

Telophase

Cytokinesis The cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes

Regulating the Cycle A protein call cyclin helps regulate the cell cycle in eukaryotic cells. They respond to internal and external events. These proteins are regulators.

When Things Go Wrong Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, they form masses of cells called tumors that can damage surrounding tissues.

Cancer