Cell devision & stem cells

• Mitosis is a type of cell division for growth and repair
• Meiosis is a type of cell division to produce gametes for sexual reproduction
• Stem cells differentiate into specialised cells during organism development
• Chromosomes carry genetic information in DNA and are found in pairs in the nucleus
• Each human body cell contains 46 chromosomes arranged into 23 pairs
• Mitosis ensures that each new cell produced has the same genetic information
• Cells divide by mitosis when an organism grows, needs to replace worn-out cells, or repair damaged tissue
• Cancer cells grow and divide uncontrollably, producing a tumour
• Carcinogens are agents that cause cancer by damaging DNA and causing mutations
• Risk factors for cancer include lifestyle factors like viruses, smoking, alcohol, UV radiation, and diet
• Industrial and environmental factors like exposure to ionising radiation and chemical carcinogens also increase the risk of cancer
• Cells divide by mitosis for growth and repair
• Cells divide by meiosis to produce gametes for sexual reproduction
• Stem cells differentiate into specialised cells during the development of organisms
• Stem cells are undifferentiated cells found in foetuses, embryos, and some adult tissues
• If cells are removed from the embryo, they will differentiate into any cell type, known as embryonic stem cells
• Adult stem cells can be found in limited numbers in various regions of the body such as the brain, eyes, blood, heart, liver, bone marrow, skin, and muscle
• Adult stem cells can differentiate into related cell types only, for example, bone marrow cells can differentiate into blood cells and cells of the immune system
• Stem cells can be transplanted into patients to treat medical conditions and diseases
• Stem cells have the potential to replace damaged or destroyed cells in conditions like type 1 diabetes, multiple sclerosis, spinal cord or brain injury
• Stem cells used for transplants could be embryonic stem cells or adult stem cells
• Embryonic stem cells can differentiate into a wider range of cell types, while adult stem cells differentiate into a narrower range of cell types
• Benefits and risks associated with the use of stem cells in medicine
• Benefits include treating untreatable conditions, growing organs for transplants, and research
• Using your own stem cells eliminates rejection, the need for a donor, and tissue typing
• Clinical, ethical, and social issues are associated with the use of stem cells in medicine
• Clinical issues include the uncertainty of therapy success, difficulty in finding suitable donors, and mutations in cultured stem cells
• Ethical issues involve the creation and destruction of embryos for therapy, and the view of embryos as commodities
• Social issues include educating the public about stem cells, weighing the benefits against risks, and potential exploitation of patients by commercial clinics
• Cell division in plants occurs in regions called meristems
• Meristem is a region in plant shoots and roots where cells are dividing and undergoing mitosis
• Cells of the meristem can differentiate to produce all types of plant cells at any time during the life of the plant
• The main meristems are close to the tip of the shoot and the tip of the root
• In a growing shoot, new cells are continuously produced near the tip
• As cells age, they move further away from the tip and become differentiated