Meiosis Or reduction division.

What is the Difference between Mitosis and Meiosis

Mitosis Occurs in body (somatic) cells 2n -> 2n 46 to 46 (in Humans) Diploid to Diploid Goes through PMAT once Meiosis Occurs in gonads to make gametes (sex cells) sperm and egg 2n -> 1n 46 to 23 (in Humans) Diploid to Haploid Goes through PMAT twice

Meiosis

Independent Assortment occurs during anaphase 1 of Meiosis

Spermatogenesis How a body makes sperm cells. Occurs in the testes One 46 chromosome cell becomes four spermatids containing 23 chromosomes.

Oogenesis Oogenesis makes oocytes. Egg=Oocyte Occurs in the Ovaries. (before birth) One cell containing 46 chromosomes becomes four cells containing 23 chromosomes. Three of the cells called Polar Bodies die. One Cell Survives and becomes an oocyte.

Asexual vs. Sexual Reproduction Asexual reproduction is the production of an offspring from one parent. –Budding (Jellyfish, Hydras, some Plants) –Binary Fission (bacteria) –Mitosis is used (no genetic difference from parents) Sexual Reproduction is the production of an offspring from two parents. –Meiosis is used ( there is genetic variation from parents)

Plants can send out runners that make new plants like this strawberry plant

Jellyfish during the Polyp phase bud

Hydra Budding

P List two ways that mitosis differs from meiosis. 2.During which stage of meiosis is the diploid number of chromosomes reduced to the haploid number of chromosomes? 3.How many chromosomes do gametes normally contain? 4.Explain the role of crossing over to ensure genetic variation. 5.Describe the primary difference between spermatogenesis and oogenesis. 6.Explain why the chromosomes in haploid cells that are produced in meiosis I look different from those produced in meiosis II