B6

• DNA


  Deoxyribonucleic acid, the chemical that all of the genetic material in a cell is made up from
• DNA

  • It contains coded information - basically all the instructions to put an organism together and make it work
  • It determines what inherited characteristics you have
• DNA is found in the nucleus of animal and plant cells, in really long structures called chromosomes
• Chromosomes normally come in pairs
• DNA


  A polymer made up of two strands coiled together in the shape of a double helix
• Gene


  A small section of DNA found on a chromosome that codes for a particular sequence of amino acids which are put together to make a specific protein
• Only 20 amino acids are used, but they make up thousands of different proteins
• DNA determines what proteins the cell produces, e.g. haemoglobin, keratin
• The type of cell is determined by the proteins it produces, e.g. red blood cell, skin cell
• Genome


  The entire set of genetic material in an organism
• Understanding the human genome

  • Allows scientists to identify genes linked to different types of disease
  • Helps understand inherited diseases and develop effective treatments
  • Allows tracing the migration of human populations around the world
• Sexual reproduction


  1. Genetic information from two organisms (a father and a mother) is combined to produce offspring which are genetically different to either parent

  2. The mother and father produce gametes by meiosis (egg and sperm cells)

  3. The egg and sperm cell fuse together (fertilisation) to form a cell with the full number of chromosomes
• Sexual reproduction produces variation in the offspring
• Asexual reproduction

  1. There's only one parent so the offspring are genetically identical to that parent

  2. Happens by mitosis - an ordinary cell makes a new cell by dividing in two