1.1 Division and differentiation in human cells

• What type of cell division do somatic stem cells undergo?

  Mitosis
• What do germline stem cells divide to produce?

  Haploid gametes
• How do somatic stem cells maintain their population?

  By dividing through mitosis
• What is the chromosome complement maintained during mitosis?

  Diploid
• What are germline cells?

  Gametes (sperm and ova)
• Where are germline stem cells found?

  In the ovaries and testes
• What type of chromosomes do diploid cells have?

  23 pairs of homologous chromosomes
• What are homologous chromosomes?

  Chromosome pairs from each parent
• What happens during meiosis in germline stem cells?

  It produces haploid gametes
• How does meiosis contribute to genetic variation?

  By producing genetically different gametes
• What are the stages of meiosis and their functions?

  • Meiosis I: Separates homologous chromosomes
  • Meiosis II: Separates sister chromatids
• What is the result of the first division in meiosis?

  Two haploid cells
• What is the result of the second division in meiosis?

  Four haploid gamete cells
• What is the chromosome number in haploid gametes?

  23 single chromosomes
• What type of cells are produced by mitosis?

  Diploid cells
• What is cellular differentiation?

  The process of cells becoming specialized
• What is the role of specialized cells in the human body?

  To perform specific functions
• What triggers the differentiation of unspecialized cells?

  Gene expression changes
• What is gene expression?

  Activation of a gene to produce protein
• How many genes are typically switched on in specialized human cells?

  About 3-5%
• What is the organization of cells in humans?

  • Cells form tissues
  • Tissues form organs
  • Organs form organ systems
  • Organ systems make up the organism
• What is an organ?

  A working unit of tissues
• What are organ systems?

  Teams of organs working together
• What are the two types of stem cells?

  Embryonic and tissue stem cells
• What is the difference between pluripotent and multipotent stem cells?

  Pluripotent can differentiate into all cell types
• What is the primary use of tissue stem cells?

  Growth, repair, and renewal of tissue
• What is the current approved medical use of stem cells in the UK?

  Bone marrow transplants
• What is the purpose of stem cell research?

  To understand cell processes and develop therapies
• How are stem cells used in treating leukaemia?

  By transplanting healthy stem cells
• How are skin grafts created using stem cells?

  By growing new skin from patient’s stem cells
• What is the function of corneal stem cells?

  To replace damaged corneal cells
• What is the significance of stem cell therapy for vision?

  It restores the ability to see
• What is necessary for patients who have lost most of their skin?

  A skin graft
• How can doctors save patients who have lost skin?

  By using stem cells to grow new skin
• What is the first step in the skin graft procedure using stem cells?

  Take stem cells from an unburned area
• Why is the new skin not rejected by the patient's body?

  It is made from the patient's own cells
• What limitations does the new skin have after grafting?

  It cannot grow hair and lacks sweat glands
• What are scientists currently trying to solve regarding new skin?

  The inability to grow hair and sweat glands
• What is the cornea?

  The transparent front part of the eye
• What is the only proven stem-cell-based therapy for the eye?

  Corneal repair