Cell Division

• 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. These can be arranged into 23 pairs. Each chromosome in a pair carries the same types of genes
• Sex chromosomes


  In females, the two chromosomes are identical in shape. There are two X chromosomes. Females are referred to as XX. In males, one of the chromosomes is a different in shape. There is an X and also a Y chromosome. Males are referred to as XY
• Mitosis ensures that when a cell divides each new cell produced has the same genetic information
• DNA exists in a cell's nucleus within structures called chromosomes
• Each chromosome is made from a single molecule of DNA, but when a cell is ready to divide, the DNA copies itself, then coils and condenses to form the chromosomes that we can see in micrographs
• Chromosomes


  Carry genetic information in a molecule called DNA
• Mitosis


  A type of cell division which produces daughter cells identical to the parent
• Cell cycle


  1. Cell growth

  2. DNA synthesis

  3. Mitosis
• Mitosis ensures that when a cell divides each new cell produced has the same genetic information
• Cells divide


  • When an organism grows
  • When an organism becomes damaged and needs to produce new cells
• Daughter cells


  The new cells produced when a cell divides
• The length of different stages of the cell cycle can be estimated using the formula: Length of time in phase = (observed number of cells at that stage/total number of cells observed) x total length of time of cell cycle
• 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 - Transport substances, defend the body, regulate temperature
  • Excretory system cells - Remove waste products and unwanted substances, regulate the water content of the body
  • Muscular system cells - Bring about movement
  • Nervous system cells - Respond to internal and external stimuli and conditions, carry messages for the body work as a coordinated whole
  • Respiratory system cells - Deliver oxygen for respiration and remove waste
  • Reproductive system cells - Bring about fertilisation to produce new offspring
  • Skeletal system cells - To bring about movement, support and protect internal structures, produce blood cells, store and release calcium
• Specialised cells in plants


  • Leaf palisade mesophyll cells - Carry out photosynthesis
  • Leaf spongy mesophyll cells - Allow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis
  • Leaf guard cells - Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen
  • Phloem sieve tube cells - Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed
  • Phloem companion cells - Provide the energy required for transporting substances in sieve tubes
  • Xylem vessel cells - Transport water and dissolved minerals from the roots, up the plant
  • Meristem cells - Produce new cells as they divide
• 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


  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
  • Could be used to replace cells that have been damaged or destroyed
• Conditions stem cells could treat


  • Type 1 diabetes
  • Multiple sclerosis
  • Paralysis from spinal cord injury