Cell Cycle & Mitosis By: Valeria Acosta
The Cell Cycle • Every cell goes through a process of growth, this is called the cell cycle. • New cells start at G1 or Gap1, go on to an S phase, and then G2 or Gap2 before Mitosis or Cell division. • Some cells will no longer divide and they exit the cell cycle in G1 • As one cell enters Mitosis, two cells exit which are exact replicas or clones of the original “parent” cell.
Mitosis Description • The process of mitosis is divided into 6 stages. The Interphase, Prophase, Metaphase, Anaphase, Telophase, and cytokinasis. At Interphase, there is only one cell, but after cytokinasis there are two identical cells. • Before mitosis can take place, the cell need to store enough energy to drive the chemical processes during the cell division. During this period of time, there is intense cellular activity. The cell grows in size. The length of the grow phase varies between a few hours to a few months. We the cell has stored enough energy, it is ready to divide itself.
Mitosis • Mitosis occurs in order for organism to grow and develop. In order to replenish dead or dying cells such as skin cells, cells in the digestive tract and in the fertilized egg. • There are 4 main phases: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis follows and one cell becomes two.
Mitosis is divided into 6 stages • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis
Interphase • This phase encompasses all of the G 1, S, and G2 phases of the cell cycle. The chromatin is diffuse. • It may not look like much is going on here, but there is a lot of activity, because the cell must prepare for Mitosis: protein synthesis, DNA synthesis, replication of other cellular structures too.
Prophase • Major processes during this phase: • Chromosomes condense and form visible bodies ( DNA was replicated in S phase) • Nuclear envelope breaks down.
Metaphase • Chromosomes attached to spindle fibers line up in the middle of the cell. • Spindle fibers attach to the centromeres and other places along chromosome.
Anaphase • The last bit of DNA at the centromere replicates to allow the centromere to split. • The sister chromatids separate and pulled to opposite sides of the cell.
Telophase • Chromosomes now uncoil. • Nuclear envelope reappears and surrounds the chromosomes Cytokinesis. • The cytoplasm and all its contents are divided between the 2 daughter cells.
Cytokinesis • Cytoplasm divides • Two new daughter cells are now separate.