During a study of wound healing in mammalian skin, researchers track a population of stem cells. These stem cells divide by mitosis to generate new skin cells. The researchers observe that after many cycles of cell division, the chromosomes in some cells appear shorter at the ends. In a separate culture, some cells lose the ability to regulate division and form a mass of abnormal cells.
With reference to the mitotic cell cycle:
(i) Outline the stages and key events that a stem cell undergoes during a single cycle of division.
(ii) Explain the role of telomeres in preventing loss of genetic information during chromosome replication.
(iii) Describe how the observed shortening of chromosome ends is related to the role of stem cells in tissue repair.
(iv) State how uncontrolled cell division can lead to tumour formation.