Cell division & stem cells

• What is a chromosome?

  A linear DNA molecule tightly coiled around proteins that carries genetic information.
• How many pairs of chromosomes do human cells contain?

  23 pairs of chromosomes.
• Why are chromosome pairs not identical?

  They contain different alleles.
• What determines the sex of an individual?

  Same sex chromosomes.
• What chromosomes do males have?

  X and Y chromosomes.
• What chromosomes do females have?

  Two X chromosomes.
• What is mitosis?

  The division of a cell to produce two genetically identical daughter cells with a full set of chromosomes.
• How many divisions occur during meiosis?

  Two divisions.
• What is the purpose of mitosis?

  To allow organisms to grow, replace old cells, and repair damaged tissue.
• What is meiosis?

  A type of cell division that creates four genetically different daughter cells known as gametes.
• How many chromosomes do daughter cells have after meiosis?

  Half the number of chromosomes (23).
• What are the key characteristics of mitosis?

  • Occurs in all somatic cells
  • Produces two daughter cells
  • Daughter cells are genetically identical
  • Daughter cells have the same number of chromosomes (46)
  • Important for growth, repair, and replacement of damaged cells
• What can uncontrolled cell division lead to?

  The formation of a tumor (cancer).
• What are stem cells?

  Unspecified cells that can differentiate into a range of different types of cells.
• Where can stem cells be found in humans?

  In early embryos and tissues like bone marrow.
• What are the advantages and disadvantages of using stem cells?

  Advantages:

  • Can differentiate into various cell types
  • Potential for repairing damaged tissues

  
  

  Disadvantages:

  • May be difficult to find
  • Risk of rejection in transplantation
  • Long-term side effects unknown
  • Ethical issues surrounding embryonic stem cells
• What is a major ethical issue related to stem cells?

  Embryos used for stem cells are usually destroyed.
• What are the sources of stem cells?

  • Embryonic tissue
  • Adult tissues (e.g., bone marrow)
• What is the outcome of mitosis in terms of daughter cells?

  Two genetically identical daughter cells are produced.
• What is the outcome of meiosis in terms of daughter cells?

  Four genetically different daughter cells are produced.
• How does the chromosome number in daughter cells after meiosis compare to the mother cell?

  Daughter cells have half the chromosomes than the mother cell.
• What is the significance of alleles in chromosomes?

  Alleles are different versions of a gene found on chromosomes.
• What is the role of genes in chromosomes?

  Genes code for characteristics.
• What happens to stem cells during differentiation?

  They develop into specialized cells.
• What is the main purpose of stem cells in medical applications?

  To repair and replace damaged or old tissue.
• What is the relationship between mitosis and cancer?

  Uncontrolled mitosis can lead to cancer.