Cell cycle Mitosis

Cell Cycle Think about how fast the weather changes at times Most cells in an organism go through a cycle of growth, development, and division called the cell cycle Through the cell cycle, organisms grow, develop, replace old or damaged cells, and produce new cells There are 3 main phases in the cell cycle: interphase, mitosis, and cytokinesis Depending on the type of cell, it can take anywhere from 8 minutes to a year for cells to divide

Interphase Interphase is the period during the cell cycle of a cell’s growth and development A cell spends most of its life in interphase During interphase a copy of the hereditary material must be made so that each of the two new cells will get a complete copy Once the hereditary material has been copied, it has been arranged into pairs of identical chromosomes called sister chromatids held together by the centromere NO DIVISION TAKES PLACE!!!

Mitosis Mitosis is the stage of the cell cycle in which the cell actually divides; at the end, the original cell no longer exists There are 4 stages to mitosis: prophase, metaphase, anaphase, and telophase

Prophase=Prepare The nucleus is going to prepare to divide Two small structures called centrioles move to opposite ends of the cell. Between the centrioles, threadlike spindle fibers begin to stretch across the cell.

Metaphase=Middle Metaphase is when the pairs of chromatids line up across the middle of the cell. The centromere of each pair usually becomes attached to two spindle fibers, one from each side of the cell.

Anaphase=Apart During anaphase the spindle fibers shorten and each pair of chromatids begin to move apart. The separated chromatids are now called chromosomes. As they move to opposite sides, the cell begins to get longer Anaphase is complete when the identical sets of chromosomes are at opposite ends of a cell

Telophase=Two The final stage of mitosis During telophase the spindle fibers start to disappear, the chromosomes start to uncoil, and two nuclei form.

Cytokinesis After the cell goes through interphase and mitosis, the last phase of the cell cycle is cytokinesis Cytokinesis is when the cell membrane pinches in the middle and the cytoplasm divides The 2 new cells that result after cytokinesis are called daughter cells After the nucleus has divided, the cytoplasm separates and two new cells are formed. Following cytokinesis new cells begin interphase again