meosis

• • gametes are produced by meiosis
• • before cell divides, gentic inofrmation duplicated
  • two chromosomes fromed - each arm being copies of each other
  • chromosomes arrange into pairs
• • first divison - chromosomes line up in centre of cell
• • pairs are pulled apart so each new cell has one copy of each chromosome
• • second division - chromosomes line up again and are pulled apart
• • four gametes produced
  • each have 23 chromosomes
  • each gamete is gentically different
• • after two gametes fuse during fertilisation, new cell dvides by mitosis to make copy
  • mitosis repeats to produce lots of new cells in embryo
  • cells start to differentiate as embryo develops into different types of specialised cells