BIOL 2905 Lecture Notes - Lecture 21: Zygosity, Mitosis, Aneuploidy
Document Summary
Independent assortment & random segregation: one chromosomes in not influencing the segregation of another, completely random & independent of one another, how many possible combinations, 2n organisms 2n. Independent assortment in meiosis: individual heterozygous at 2 genes (loci)- genes are on different chromosomes, locus describes location of gene on chromosome, meiosis results in 4 haploid cells that. Combinations of gametes in fertilization: allows for more variability- which sperm cell & which egg cells combines, each egg & sperm cell has different genes. Comparison of meiosis & mitosis: mitosis in anaphase, the sister chromatids are spilit; same with meiosis, mitosis is 2 identical daughter cells; meosis produces 4 different cells. Mistakes in meiosis: non-junction: failure of chromosomes segregation in meiosis i or meiosis ii, when separation during anaphase is not equal, it can occur in meiosis one or meiosis 2. Results in offsprings with incorrect number of chromosomes: euploids: normal number of chromosomes, aneuploid: extra or missing chromosomes.