Presentation on theme: "Group Work: How many chromosomes are found in human cells?"— Presentation transcript:
1 Aim: How is chromosome number maintained in the species from generation to generation? Group Work:How many chromosomes are found in human cells?How many chromosomes pass from each parent to the child?Human chromosome number is 46 or 23 pairs.
2 Outcome of meiosis is that each cell gets half the number of chromosomes (one chromosome of each pair)
3 Oogenesis Egg formation takes place in the ovaries Egg contains the n number of chromosomes
4 SpermatogenesisSpermatogenesis — takes place in the testes. Each sperm cell contains the n number of chromosomes
5 Comparison of (Meiosis) Spermatogenesis Oogenesis 1. production of sperm cell from puberty to the death of the male2. produce 4 haploid sperm cells3.very small cells with a tail1. viable eggs are produced from puberty to menopause2. produce 1 haploid egg cell and three smaller polar bodies3. large cells
6 Mus musculus (house mouse) 40 Drosophila melanogaster (fruit fly) 8 Diploid numbers of some commonly studied organisms (as well as a few extreme examples)Homo sapiens (human)46Mus musculus (house mouse)40Drosophila melanogaster (fruit fly)8Caenorhabditis elegans (microscopic roundworm)12Saccharomyces cerevisiae (budding yeast)32Arabidopsis thaliana (plant in the mustard family)10Xenopus laevis (South African clawed frog)36Canis familiaris (domestic dog)78Gallus gallus (chicken)Zea mays (corn or maize)20Muntiacus reevesi (the Chinese muntjac, a deer)23Muntiacus muntjac (its Indian cousin)6Myrmecia pilosula (an ant)2Parascaris equorum var. univalens (parasitic roundworm)Cambarus clarkii (a crayfish)200Equisetum arvense (field horsetail, a plant)216All animals have a characteristic number of chromosomes in their body cells called the diploid (or 2n) number