2.1.6 - cell division, cell diversity + cell organisation

•  cell cycle: g1 ➡️ s ➡️ g2 ➡️ mitosis
•   stem cells : undifferentiated cells which are genetically identical and have the ability to develop into various types of cells
• mitosis - a form of cell division that produces identical cells
• stages of mitosis : prophase, metaphase, anaphase, telophase
• cytokinesis - parent and replicated organelles move to opposite ends of the cell and the cytoplasm divides, creating two identical daughter cells
• interphase - when the cell grows and prepares to divide, chromosomes and some organelles are replicated, chromosomes also begin to condense
• during prophase the nuclear envelope breaks down and disappears. the chromosomes condense and centrioles move to opposite poles of the cell for spindle formation
• metaphase - chromosomes move to the metaphase plate equator and attach to the spindle fibres via centromeres
• in anaphase the sister chromatids are dragged apart and separates to opposite poles of the cell
• during telophase the nuclear envelope reforms, the spindle fibres are broken down and disappear. the chromosomes uncoil
• genetic variation in meiosis is achieved through crossing over of chromatids and independent assortment of chromosomes
• crossing over of chromosomes is where pairs of chromosomes line up and exchange some of their genetic material
• independent assortment of chromosomes - there are various combinations of chromosome arrangement
•  meiosis - a form of cell division in which the chromosome number is halved
•  there are no centrioles in plants, so production of a new cell wall divides them to create two daughter cells