cell division

• Chromosomes carry genetic information in a molecule called DNA
• Mitosis ensures that when a cell divides each new cell produced has the same genetic information
• DNA


  Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being
• Chromosome


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


  A photograph taken of a microscopical image
• Each human body cell contains 46 chromosomes, arranged into 23 pairs
• In females, the two chromosomes in the 23rd pair are identical in shape (two X chromosomes)
• In males, the 23rd pair consists of one X chromosome and one Y chromosome
• Chromosomes


  Carry genetic information in a molecule called DNA
• Mitosis


  A type of cell division that ensures each new cell produced has the same genetic information as the parent cell
• Cell cycle


  1. Cell growth

  2. DNA synthesis

  3. Mitosis
• The single strand of DNA that makes up each chromosome produces an exact copy of itself during the cell cycle
• Daughter cells


  The new cells produced when a cell divides
• In mitosis, two daughter cells are produced, each identical to the parent cell
• Estimating length of cell cycle stages

  Observed number of cells at that stage / Total number of cells observed x Total length of cell cycle
• Mitosis is a type of cell division which produces daughter cells identical to the parent
• Chromosomes


  Carry genetic information in a molecule called DNA
• Mitosis


  A type of cell division that ensures each new cell produced has the same genetic information
• Stem cells


  Cells that have not undergone differentiation
• Stem cells


  • Found in foetuses, embryos and some adult tissues
  • 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, e.g. red blood cell
• Embryo


  An organism in the early stages of development that develops from a fertilised egg
• Embryonic stem cells


  A type of stem cell found in the embryo, capable of dividing into almost any cell type
• Adult stem cells


  A type of stem cell found in specific locations in adults that can only differentiate into a limited number of related cell types
• Locations of adult stem cells

  • Brain
  • Eyes
  • Blood
  • Heart
  • Liver
  • Bone marrow
  • Skin
  • Muscle
• Bone marrow


  Soft tissue found inside bones that produces new blood cells
• Immune system


  The body's defence system against entry of any foreign body, including pathogens and agents such as pollen grains
• Meristem


  A region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis
• Vacuole


  A space within the cytoplasm of plant cells that contains cell sap
• Chromosomes


  Carry genetic information in a molecule called DNA
• Mitosis


  A type of cell division that ensures each new cell produced has the same genetic information
• Fertilised egg cell (zygote)


  • It must divide to produce a multicellular organism
  • It must differentiate so its cells develop features to fulfil specific roles
• Specialised cells in animals

  • Circulatory system cells
  • Excretory system cells
  • Muscular system cells
  • Nervous system cells
  • Respiratory system cells
  • Reproductive system cells
  • Skeletal system cells
• Circulatory system cells


  Specialised to transport substances, defend the body, regulate temperature
• Excretory system cells


  Specialised to remove waste products and unwanted substances, regulate the water content of the body
• Muscular system cells


  Specialised to bring about movement
• Nervous system cells


  Specialised to respond to internal and external stimuli and conditions, carry messages for the body to work as a coordinated whole
• Respiratory system cells


  Specialised to deliver oxygen for respiration and remove waste