Cell division and stem cells

• Chromosome


  The structure made of DNA that codes for all the characteristics of an organism
• DNA


  The part of the cells of living things that carries information about how they look and function
• Gene


  The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production
• Mitosis


  Cell division which ensures that, when a cell divides, each new cell produced has the same genetic information
• Daughter cells


  When a cell divides, the new cells produced are called daughter cells
• Cell division occurs when an organism grows, needs to replace worn-out cells, or needs to repair damaged tissue
• Mitosis produces daughter cells identical to the parent cell, and maintains the number of chromosomes
• Cancer


  A disease caused by normal cells changing so that they grow and divide in an uncontrolled way. The uncontrolled growth causes a lump called a tumour to form
• Carcinogen


  A chemical or other agent that causes cancer
• Mutation


  A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes
• Ultraviolet radiation


  A high energy part of the electromagnetic spectrum associated with sunburn and skin cancer
• Ionising radiation


  Radiation that is able to remove electrons from atoms or molecules to produce positively charged particles called ions
• Lifestyle factors that increase cancer risk

  • Viruses linked with cancer, such as the human papilloma virus (HPV)
  • The chemical carcinogens in cigarette smoke
  • Alcohol intake
  • Exposure to ultraviolet radiation
  • A poor diet with increased fat and salt intake, as well as the consumption of certain foods
• Industrial and environmental factors that increase cancer risk


  • Exposure to ionising radiation, like ultraviolet radiation in sunlight
  • Exposure to chemical carcinogens such as those in cigarette smoke
• Mitosis


  Cell division for growth and repair
• Meiosis


  Cell division to produce gametes for sexual reproduction
• Stem cells


  Cells that differentiate into specialised cells during development
• 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
• Gamete


  Sex cell (sperm in males and ova/eggs in females)
• Zygote


  A fertilised egg cell
• Chromosome


  The structure made of DNA that codes for all the characteristics of an organism
• Embryo


  An organism in the early stages of development
• In human beings, each gamete contains 23 chromosomes, half the number found in the other cells of the body
• When the male and female gametes fuse, they become a zygote, which in turn becomes a new embryo containing the full 46 chromosomes – half from the father and half from the mother
• This fusion of gametes is called fertilisation
• Gametes are formed by a type of cell division called meiosis
• In animals the gametes are sperm and eggs
• In flowering plants the gametes are pollen and eggs
• In meiosis, copies of the genetic information are made, the cell divides twice to form four gametes, each with a single set of chromosomes known as haploid cells
• All gametes are genetically different from each other, they show variation
• Stem cells


  Cells found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells
• Differentiation


  When an unspecialised cell becomes a more specialised cell type
• Specialised cell


  A cell that has become differentiated to carry out a particular function, eg red blood cell
• Embryonic stem cells


  • Cells removed from the embryo that will differentiate into any cell type
• Adult stem cells


  • Stem cells that remain in the bodies of adults and can differentiate into related cell types only
• Therapeutic cloning


  Using cloning technology for medicinal purposes, e.g. to use a person's DNA to clone one of their organs for use in transplanting
• Stem cells can divide to produce new cells, which can then divide into different cell types
• Stem cells have the potential to be transplanted into patients to treat medical conditions and disease