mitosis

• during interphase the cells DNA is replicated to double its DNA and organelles
• chromosomes are made of two strands called chromatids joined in the middle by a centromere
• in prophase the chromosomes condense and become shorter, centrioles start moving to opposite ends of the cell and the nuclear envelope breaks down
• in metaphase the chromosomes line up in the equator of the cell and be some attached to the spindle fibres by a centromere
• in anaphase the centromeres divide whinch separates the chromosomes into chromatids, the spindles contract and pull the chromatids to opposite ends of the cell
• in telophase the chromatids uncoil and become long and thin. a nuclear envelope reforms
• in cytokinesis the cytoplasm divides to form two genetically identical daughter cells
• some treatments for cancer are made to control the rate of mitosis in the tumour cells to stop them from dividing, however these treatments can distinguish between tumour and healthy body cells
• 1. add 1 M of HCL to a boiling tube, just enough to cover the root then place in a water bath of 60 degrees
  2. use a scalpel and cut 1 cm from the tip of the root
  3. transfer the tip into the boiling tube containing HCL
  4. remove the tip and rinse well with water and leave to dry.
  5. place the root tip on a slide and cut 2 mm from the end
  6. use a mounted needle to break the tup open and spread the cells out thinly
  7. add the stain and leave for a few minutes
  8. add the cover slip and push down firmly to squash the tissue
  9. look through an optical microscope
• mitotic index = number of cells with visible chromosomes / total number of cells observed
• 1. start by clipping the slide on the stage
  2. set the lowest objective lens
  3. use the corse adjustment knob to bring the stage up
  4. look down the eyepiece and move the knob to focus the image
  5. then repeat with a higher magnification