3.2 Fertilisation

• The process of fertilization begins with the adults male and female.
• The cells in testis and in ovaries have a complete cell of chromosomes                                                      - this is called diploid (2n) which is a complete set of chromosomes and for human it is 46
• The cells divide to form cells with half sets of chromosomes, this type of cell division is called meiosis  - > this makes the cell go from a diploid number to a haploid number(n) which is a 1/2 set so in humans it is 23 (there are 23 chromosomes in the sperm cell and 23 chromosomes in the egg cell)
• During sexual reproduction the two cells are brought together and joint/fused together, so forms 1 cell. This process is know as fertilization. Which involves the combining of half set of chromosomes and another half set of chromosomes to make a full set of chromosomes (n+n=2n/in humans 23+23=46)
• This cell is known as a zygote.
• We have a combination with a male and female chromosomes. This cell then goes through the process of cell division called mitosis, in which the cells will divide to get 2 cells, they will both contain 46 chromosomes. They will then divide. All cells contain 2n diploid number.
• When we have sufficient cells, this will then be called an embryo.
• This principle holds truth for all sexually reproducing organisms but the numbers are for human only

credits to Daniel :)