Cell Cycle

• What is mitosis needed for?

  The growth of multicellular organisms and repairing damaged tissues
• What is interphase?

  A period of cell growth and DNA replication which is split up into G1, S and G2. Mitosis happens after this.
• What is G1?

  Cell grows and new organelles and proteins are made
• What is S?

  Cell replicates its DNA ready to divide by mitosis
• What is G2?

  Cell keeps growing and proteins needed for cell division are made
• What are the 4 stages of mitosis?

  Prophase, Metaphase, Anaphase, Telophase
• What is prophase?

  The chromosomes condense, getting shorter and fatter. Tiny centrioles (bundles of proteins) start moving to opposite ends of the cell forming a spindle (network of protein fibres). The nuclear envelope (membrane around the nucleus) breaks down and chromosomes lie free in the cytoplasm
• What is Metaphase?

  The chromosomes (each with 2 chromatids) line up along the middle of the cell and become attached to the spindle by their centromere
• What is anaphase?

  The centromeres divide, separating each pair of sister chromatids. The spindles contract pulling chromatids to opposite poles of the spindle, centromere first. This makes the chromatids appear v-shaped
• What is telophase?

  The chromatids reach opposite poles on the spindle. They uncoil and become long and thin again and are now called chromosomes again. A nuclear envelope forms around each group of chromosomes so there are now 2 nuclei. The cytoplasm divides (cytokinesis) and there are now 2 daughter cells that are genetically identical to the original cell and each other. Mitosis is finished and each daughter cell starts the interphase part of the cell cycle to get ready for the next round of mitosis