The Cell Cycle the amazing! incredible! I-cant wait-to- hear-more story of how cells divide Stages of the Cell Cycle INTERPHASE G1 phase: The period prior to the synthesis of DNA when cells do most of their growing. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.G1 phase: The period prior to the synthesis of DNA when cells do most of their growing. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase. S phase: The period during which DNA is synthesized and chromosomes are replicated. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.S phase: The period during which DNA is synthesized and chromosomes are replicated. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis. G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size; many of the organelles and molecules required for cell division are produced. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase. When the G2 is completed the cell is ready to enter the M phase and begin the process of cell division.G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size; many of the organelles and molecules required for cell division are produced. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase. When the G2 is completed the cell is ready to enter the M phase and begin the process of cell division. In the latter part of interphase, the cell still has nucleoli present. The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin. In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus. PROPHASE Longest stage of mitosis Chromatin condenses into chromosomes Centrioles separate and go to opposite poles Spindle begins to form from microtubules Nuclear envelope begins to break down Chromosomes split into two parts called chromatids connected at the centromere Prophase Interphase METAPHASE Spindle fibers arch across cell between the centrioles Chromosomes line up across the equator of the cell Chromosomes attach to spindle fibers at the centromere ANAPHASE Centromeres duplicate and split Sister chromatids separate and become individual chromosomes Spindle fibers begin to pull chromosomes to the poles Anaphase ends when chromosomes stop moving TELOPHASE Final phase of mitosis Cell begins to pinch in the center splitting the cell into two daughter cells Duplicated cytoplasmic organelles are equally distributed into each new cell Spindles disappear and centrioles lose their asters Chromosomes begin to disperse forming chromatin Nuclear membrane reforms and nucleolus become visible in each daughter nucleus MID-TELOPHASE LATE TELOPHASE CYTOKINESIS M phase of cell cycle Two nuclei are present Duplicated organelles present in cytoplasm Final cytoplasmic division occurs as cell membrane continues to pinch in to center of animal cells In plant cells, cell plate forms midway between nuclei and gradually develops into a separating membrane; cell wall begins to appear Cytokinesis usually occurs at the same time as telophase Cytokinesis- Animal Cell Mitosis 3 rap it up Proteins= Internal External CELL REGULATORS