Sexual reproduction , Meiosis and gamete formation

• Reproduction occurs in all organisms
• DNA is important as it allows new proteins to be synthesised
• Mutations in the DNA can have serious implications
• Sexual reproduction involves the formation of a new organism by combining the genetic material of two organisms
• During sexual reproduction, the nuclei of the male and female gametes are fused to create a zygote through fertilisation
• Gametes contain half the number of chromosomes (haploid) which combine to create a full complement of chromosomes (diploid) in a human embryo
• Gametes in animals are sperm and eggs, while in flowering plants they are pollen and eggs
• The offspring produced in sexual reproduction are genetically different from each other and the parents, resulting in variation
• Meiosis is the reduction division in a cell where the chromosome number is halved from diploid to haploid
• Meiosis creates genetically different gametes through two cell divisions to form four gametes, each with a single set of chromosomes
• Fertilisation is the fusion of the nucleus of a male gamete with the nucleus of a female gamete
• When gametes combine, they merge the two sets of chromosomes to create a diploid zygote, which matures into an embryo
• The number of cells in the embryo increases by mitosis, and cells begin to differentiate or specialise as the embryo develops