Meiosis vocabulary Sperm male sex gamete 1 N

Meiosis vocabulary �Sperm- male sex gamete ( 1 N) �Egg- female sex gamete (1 N) �Haploid –cell containing one of each kind of chromosome (1 N) �Diploid - cell containing two of each kind of chromosome ( 2 N) �Homologous Chromosomes- paired chromosomes with genes for the same traits arranged in the same order �Meiosis –type of cell division where one cell produces four gametes, each containing half the number of chromosomes in the parent’s body cell.

Sexual vs. Asexual reproduction �Sexual reproduction- type of reproduction that requires the production of the fusion of two parent (haploid) sex cells. �Ex. Humans, dogs, most plants �Zygote - a fertilized egg �Asexual reproduction- reproduction involving only one parent cell. �Ex. Yeast/ budding & bacteria/ binary fission

Problems with Meiosis… �Non- disjunction- failure of homologous chromosomes to separate properly during meiosis- results in too many or two few chromosomes---- PROBLEMS! -- organisms with too few chromosomes often die while those with extra chromosomes often survive ex. Trisomy 21 ( an extra #21 chromosome is Down’s syndrome) �Crossing over- exchange of genetic material between nonsister chromatids from homologous chromosomes during Prophase 1 results in new allele combinations

Meiosis- purpose is for reproduction and to increase genetic variation! �Cell reproduces chromosomes and then essentially divides twice producing 4 sex cells each with half the chromosomes 4 sperm and 1 egg + 3 oocytes that eventually die off ( think about it) Two stages– Meiosis 1 and Meiosis 2 Interphase Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Interkinesis– ( break time) Prophase 2 Metaphase 2 Anaphase 2 and Telophase 2 Cytokinesis