ZOL 141 1st Edition Lecture 7 Outline of Last Lecture II Review of Mitosis phases III Meiosis a Diploid b Haploid Outline of Current Lecture IV meiosis A Meiosis 1 B Meiosis 2 Current Lecture Meiosis Takes place in germ cells to produce gametes sperm and egg Diploid cells become Haploid Two successive cell divisions one cell produces four cells o Male one cell produces four gametes sperm o Female one functional oocyte and two or three polar bodies Divided into Meiosis 1 and Meiosis 2 o Meiosis 1 reduces chromosome number to haploid o Meiosis 2 separates sister chromatids Meiosis 1 o Prophase 1 mtaohase 1 anaphase 1 telophase 1 o Cell Diploid 2n 4 chromosomes Haploid n 2 chromosomes o Prophase 1 start with replicated chromosomes two sister chromatids similar to mitosis in that nuclear envelope begins to disintegrate break down Different from mitosis in that chromosomes begin to pair up Crossing over chromosomes physically exchange parts o Metaohase 1 Pair of homologous chromosomes line up at equater o Anaphase 1 Paired homologous chromosomes separate homologous chromosomes pulled to opposite ends of cell o Telophase Cells start to separate o Up until anaphase 1 the cells are diploid four chromosomes with two chromatids each Meiosis 2 o Prophase 2 same as mitosis o Metaphase 2 All chromosomes lined up on one plane o Anaphase 2 Analogous to mitosis o Telophase 2 Cells start to separate Meiosis produces four gametes Each is haploid 2 chromosomes Each chromosome consists of one chromatid
View Full Document
Unlocking...