BIOM 3200 Chapter Notes - Chapter 20: Seminiferous Tubule, Paramesonephric Duct, Sertoli Cell
17 Oct 2017
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Identify the hormones of pregnancy, parturition and lactation and describe their function. Sexual reproduction offers a way to combine and randomize genes in a novel way in order to introduce variability into a population; this offers a way for some members of a community to survive environmental changes over evolutionary time. In sexual reproduction, germ cells, or gametes (sperm/ova) are formed within the gonads (testes/ovaries) by reductive division (meiosis). This means that in this type of combination, the number of chromosomes is halved, so each gamete receives 23 chromosomes. When the gametes combine, it is called fertilization, and this contains 46 chromosomes within a zygote (fertilized egg). Each zygote gets 23 chromosomes from each parent. This creates 23 pairs of homologous chromosomes, with the possible exception of the sex chromosomes. Each chromosome within the pair look like each other and contain similar genes. The first 22 pairs of chromosomes are called autosomal chromosomes.
