ZOL 141 1st Edition Lecture 6 Outline of Last Lecture I CELL CYCLE a Interphase b Mitosis c Cytokinesis II Mitosis is Essential to growth III Genetic Diseases Associated with problems of cell division Outline of Current Lecture II Review of Mitosis phases III Meiosis a Diploid b Haploid Current Lecture Prophase Chromosomes condense Chromosomes randomly located in nucleus Metaphase Chromosomes align at equator Anaphase Sister chromatids break apart and move to opposite poles of cell Telophase and Cytokinesis Two daughter cells with two chromosomes each stick form Suppose human sperm and eggs were produced by mitosis How many chromosomes would each sperm or egg have 46 What would happen after fertilization 92 chromosomes How many chromosomes would zygote have Fertilization process when sperm and egg fuse Zygote fertilized egg that develops into an individual Why can your body not use mitosis to make sperm or eggs Chromosome set must be reduced by half Meiosis Cell division which will reduce the number of chromosomes by half Takes place in germ cells to produce gametes sperm and egg Diploid cells become haploid Diploid vs Haploid Diploid 2n somatic cells o Somatic normal human cell o 46 chromosomes OR 23 pairs o diploid 2n o two chromosome sets one from mom one from dad o each chromosome is represented twice as a member of homologous pair homologous chromosomes have identical loci one from dad one from mom Haploid n gametes o i e egg or sperm 23 chromosomes no pairs o Haploid n o One chromosome set o Each chromosome represented once o N 2
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