Sexual reproduction and Meiosis

• Sexual reproduction involves gametes
• Gametes are sex cells. in animals they are sperm and egg cells
• during sexual reproduction, an egg cell and a sperm cell combine, this makes a new cell called a zygote
• gametes only have one copy of each chromosome which makes them haploid cells
• zygotes have two copies of each chromosome this makes them diploid cells
• in humans sperm cell - it is haploid and contains 23 chromosomes
• in humans egg cell - it is haploid and contains 23 chromosomes
• in humans zygote - it is diploid and contains 46 chromosomes
• gametes are produced by meiosis
• meiosis is a type of cell division
• meiosis produces four gametes from each parent cell
• 1. the dna in a parent cell is copied. it makes x shaped chromosomes. half of the chromosomes come from the organisms father and half from the mother
• 2) the cell divides, each cell gets half of the chromosomes
• 3) each cell divides again . the x shaped chromosomes are pulled apart. there are now 4 daughter cells , they are gametes
• each gamete is haploid (one copy of each chromosome) . they are genetically different (each has a different mix of chromosomes from the mother and father)
• each gamete is haploid (one copy of each chromosome) . they are genetically different (each has a different mix of chromosomes from the mother and father)