To protect vulnerable 16 and 17 year olds, the offences of 'abuse of a position of trust' prohibits sexual contact between adults and children under 18 in schools, colleges and residential care.
Chromosome abnormalities usually happen as a result of an error in cell division. Meiosis is the name used to describe the cell division that the egg and sperm undergo when they are developing. Normally, meiosis causes a halving of chromosome material, so that each parent gives 23 chromosomes to a pregnancy.
Cells prepare for division by replicating DNA and duplicating protein-based centrioles. When cell division begins, the cells enter into either mitotic or meiotic phases. In mitosis, the end product is two cells: the original parent cell and a new, genetically identical daughter cell. Meiosis is more complex and goes through additional phases to create four genetically different haploid cells which then have the potential to combine and form a new, genetically diverse diploid offspring.