cell division cancer癌症和细胞分裂.ppt

A Chromosome BASIC GENETICS Each cell in the human body contains two sets of 23 chromosomes Mitosis identically replicates this information Each cell therefore has the same genetic material Reproductive cells only have one set of chromosomes. These combine to make a new person with different genetic material to both parents The Stages of the Cell Cycle M stage Mitotic Stage The nucleus and cytoplasm split to make two new cells known as DIPLOID cells The Spindle A spindle is a web type structure made up of microtubule fibres. It is essential for mitosis because it arranges the chromosomes into their correct positions in preparation for cell division. Chromosomes attached to spindle during nuclear division INTERPHASE After a cell has divided, the two new cells begin the process again, the cells at this stage are in Interphase. PROPHASE The chromatin (unravelled DNA) in the nucleus, condenses to form pairs of chromosomes. Prophase Chromatin condenses (remember that chromatin/DNA replicate during Interphase), the nuclear envelope dissolves, centrioles (if present) divide and migrate, the spindle forms. METAPHASE The spindle becomes fully developed ANAPHASE The chromatid pairs are split into two (This is done by movement of the spindle fibres) The pairs then travel to opposite ends of the spindle The halved chromatids are now called chromosomes TELOPHASE REMEMBER! Interphase Prophase Metaphase Anaphase Telophase CYTOKINESIS Literally means, division of the cytoplasm Mitosis is the splitting of the nucleus. Cytokinesis is the splitting of cytoplasm It usually begins during ANAPHASE The work of Mr Paul Maddox. The Mitosis World website. Observed with place contrast microscopy. The work of Shinya Inoue and Rudolf Oldenbourge.The Mitosis World Website. Cell Turnover - The speed of mitosis Although you may have seen a speeded up video of mitosis in action. One full cycle can vary between a couple of